USRE21030E - Bone conduction hearing device - Google Patents

Description

March 14, 1939. E. H. GREIBACH `R 21,030

BONE CONDUCTION HEARING DEVICE Original Filed Nov. ll, 1935 2 Sheets-Sheet l ...ad ,w i m v, Mw 3 7. .ww Rm Y l r l 1 f r 1 f a :n 4 41 m n .Y 5 2 me a R n i/O o m m m 1.! o l N A @u N w IV/fg? ,HE m M mm /M 0 E March 14, 1939. E. GREIBACH BONE CONDUCTION HEARING DEVICE Original Filed Nov. 1l, 1955 2 Sheets-Sheet 2 xV/AZZZA INVENTQR EMIL HENRY GREI BACH BY liz/MGM ATTORNEY Reissued Mar. 14, 1939 UNITED STATES l Re. 21,030

PATENT OFFICE Original No. 2,127,468, dated August 16, 1938, Se'- rial No. 697,673, Novemberll, 1933. Reissue No. 20,896, dated October 25, 1938, Serial N0.

228,191, September 2. 1938.

This application for reissue December 23, 1938, Serial No. 247,492

61 Claims.

This invention relates to bone-conduction hearing devices and it has particular relation to bone conduction receivers for hearing aids or audiphones.

Among the objects of the invention is abone conduction receiver suitable for wearable hearing aids that is small enough for inconspicous wear in contact with hearing-inducing bones of the user and is powerful enough for imparting tothe bones the vibratory energy required for conducting the sound vibrations over the bones of the head to the hearing nerves of the inner ear and induce hearing.

The foregoing and other objects of the invention will be best understood from the Ifollowing description of the exempliilcations thereof illustrated in the accompanying `drawings in which Flg. l is a diagrammatic view of a wearable bone conduction hearing aid showing a bone conduction receiver of the invention worn on the head of a deafened person;

Fig. 2 is an enlarged sectional view of a bone conduction receiver exemplifying the invention;

Figs. 3 and 4 are vertical and horizontal sectional views, respectively, along lines 3 3 and l-I of Fig. 2;

Fig. 5 is an enlarged sectional view of another bone conduction receiver exemplifying the invention;

Figs. 6 and 7 are vertical sectional views. respectively, along lines 6-6 and 1-1 of Fig. 5,;

Fig. 8 is an enlarged sectional view of another bone conduction receiver exemplifying the invention;

Figs. 9 and 10 are vertical and horizontal sectional views, respectively along lines 9 9 and Ill-I0 of Fig. 8;

Figs. 11 and l2'are sectional views of other types of bone conduction receivers exemplifying the invention.

It has long been known that the majority of the deafened persons have impaired middle ears and can hear much better sound vibrations conducted through the bones of the head to the inner ear than sound transmitted through the air in the ear canal. However, prior to the present invention, only telephone hearing aids which transmitted sound through air in the ear canal and the middle ear have been available as hearing aids for the deafened. All prior eil'orts to make a bone conduction hearing aid device followed the principles underlying the telephone receivers and utilized an externally supported heavy stationary driving mass of a vibratory structure for vibrating a driven vibratory member usually in the form of a projecting button or rod for imparting to the bones the large-intensity small-amplitude vibrations required for inducing hearing by bone conduction. As a result all prior operative bone conduction hearing devices had to be large, heavy and cumbersome.

The invention overcomes these difllculties by utilizing the principle of preservation of the center of gravity of a moving mass system for producing large-intensity small-amplitude vibrations required for inducing hearing by boneconduction with a light, small vibratory structure which may be comfortably and inconspicuously worn coupled to a bone of the hearing inducing bone body of the user, such as on the mastoid bone of the head behind the ear.

accordance with the invention, a relatively small vibratory mass portion is resiliently carried on a hearing inducing bone of the massive body of the head of the user to form therewith a vibratory system; and this vibratory system ls subjected to internal forces induced by electric speech currents so as to accelerate the resiliently carried vibratory portion relative to the much larger mass of the head in the inverse ratio of their masses and thereby produce inertia reaction forces acting on the bone, proportional to the acceleration and the mass of the resiliently carried vibratory portion, for imparting to the bone the vibratory energy required lfor conducting corresponding vibrations of relatively large intensity and small amplitude through the bones to the inner ear and inducing intelligible hearing of speech by bone conduction.

In the practical embodiment of the invention, the resiliently carried vibratorydriving mass portion is mounted on a substantially rigid bonecoupling vibratcry contact wall portion and so combined ytherewith into a vibratory unit that when it is placed by an external force against the bone, the vibratory unit automatically assumes a stable-equilibrium coupling position along the bone so that a relatively small external force is suilicient to maintain the vibratory unit and its resilientlycarried vibratory driving mass portion in efhcient vibration transmitting coupling engagement with the bone, and no precautions are required to prevent the vibratory unit from tipping orl otherwise breaking its eilicient coupling engagement with the bone.

The stable-equilibrium coupling arrangement of the hearing inducing vibratory unit also assures highly eiilcient transmission of the vibra.- tory energy to the bones because the inertia reaction forces exerted by the accelerations of the resiliently carried vibratory driving mass portion are arranged to act in a general direction substantially perpendicular to the predominant dimentality for bringing about the accelerationof the small resiliently carried vibratory driving mass portion relative to the head body in the in'- verse ratio of their masses, and thereby translating the electric speech frequency oscillations i'nto the relatively large-intensity vibrations of small amplitude which are imparted to the bone for inducing intelligible hearing of speech by bone conduction. As a result. intelligible hearing by bone conduction is made possible with a light and inconspicuously small vibratory unit, formed essentially of the small vibratory driving mass portion and its vibratory bone-coupling contact wall portion by means of which it is resiliently carried on the bone of the head, and.

having only a small fraction of the mass and volume of the body of head.

Such small bone conduction hearing device of the invention may be designed to have a very favorable response characteristic over a wide frequency range, reaching out above the resonance frequency. Its response may be extended down to low frequencies so as to give it a good response over the speech as well as the musical range byv making its resonant frequency considerably lower than the resonance frequency of the telephone-type devices. By a small amount of damping the response may be made substantially uniform over the speech and musical frequency range.

The low resonance frequency may be secured with a relatively large effective stiffness of the rilient spring junction on which the driving vibratory mass portion is carried by building up the relatively small driving mass of all suitable mass elements of the vibratory structure.

The arrangement of the bone conduction receiver described above makes it also possible to shape the bone-coupled driven vibratory contact wall portion so that it forms a protective casing in the interior of which the driving vibratory mass portion is resiliently carried in a freely vibrating condition in which it cannot be disturbed by external forces. As a result, the bone conduction receiver of the invention may be made in the form of a light small casing unit arranged so that when it is placed by an external force against the bone, its exterior contact surface automatically assumes a stable-equilibrium coupling position along the bone in which it secures efficient transmission of the vibratory hearing inducing energy produced by the resiliently carried interior vibratory driving mass portion, which is thus protected against disturbance by external forces. d

A wearable bone conduction hearing aid equipped with a bone conduction receiver exemplifying the principles of the invention is shown in Figs. 1 to 4. It comprises a bone conduction receiver shaped in the form of a small vibrating casing which is held pressed against hearing inducing bones of the user outside the ear canal. for instance, the mastoid bone 22, by a resilient head band 2|, of steel, for instance.

lThe casing 20 consists of a rigid base 23 and a rigid cover 2l suitably secured to the base and engaged by'the head band 2| so as to press the casing 20 against the bones 22.

The receiver casing 20 is a part of a vibratory structure formed of an electromagnetic vibrating unit comprising a magnetic. armature core 3| clamped to the base 23 and carrying on a resilient magnetic armature diaphragm 3 2 a vibratory magnetic core 33 having a central pole piece 34 forming with the adjacent face of the armature a small magnetic gap. lThe vibratory structure is actuated with electric audiofrequency current oscillations supplied through terminal bushings 35 provided in a terminal block extending from the base 23 to the actuating windings of coil 3G mounted on the pole piece 3| so as to produce a vibratory motion between the mass of the resiliently carried vibratory core 33 and the armature core 3| which is held against the head and forms a part of the casing 20.

Since the mass of the head is relatively large, it resists the vibratory motion of the casing, and the smaller resiliently carried vibratory core 33 is subjected to vibratory accelerations. As a result, the resiliently carried vibratory core 33 acts as a driving member and exerts on the armature core 3| and the casing 20 which is coupled to the hard bones of the head inertia reaction forces proportional to the resiliently, carried driving vibratory mass and the acceleration imparted to it by the electric current oscillation'in the windings of the coil 36. Since the casing 2U and armature 3| which is clamped to it are in engagement with the bones, these inertia reaction forces drive the casing against the hard bones and impress on the bones relatively large oscillatory inertia reaction forces of small amplitude which are conveyed through the bones to the hearing nerves where they induce hearing corresponding to the audiofrequency oscillations` impressed on the vibratory structure.

Although the principles underlying the bone conduction receiver using anelectromagnetic vibrating structure shown in Figs. 2 to 4, lends itself for the construction of bone conduction receivers actuated by other types of vibrating structures, electromagnetic vibrating structures are particularly suitable for use in such bone conduction receivers because they permit the design of highly eiiicient vibrating structures with very small magnetic operating gaps of less than one thousandth of an( inch. Such design assures extremely -efficient operation of electro-magnetic bone conduction receivers, and makes possible the construction of bone conduction receivers of extremely small size and relatively large power output required for satisfactory Wearable bone conduction hearing aids.

Inertia reaction bone conduction receivers of the invention constructed with electromagnetic vibrating structures khave also the further advantage that they may be used as a part of a standard wearable hearing aid worn vhidden in the clothing of the user, by substituting the bone conduction receiver for the air conduction receiver without having to resort to special transformers or other accessories required when such bone conduction receivers are constructed with other types of vibrating structures. l

In Fig. 1 is shown how the electro-magnetic j to the same level.

inertia reaction boneconduction receiver of the invention is connected in the operating circuit of a prior-art wearable hearing aid. Av conventionally illustrated microphone transmitter 46 is connected in sexies with a supply battery 4| and a. cut-ofi switch 42 to the actuating coll 43 of a conventionally illustrated amplifier microphone 44 which vis connected in series with the battery 4| and the cut-ofi switch 42 by way of a rheostat 45 to the leads 46 which have terminal plugs engaging the terminal bushings 35 on receiver casing and lead to the actuating winding 36 of the receiver.

a With such wearable hearing aid assembly, sound waves of the principal audible frequency range, or, the frequency range of intelligible speech, impinging on the microphone transmitter 4|I will produce in the primary circuit including the amplifier winding 43 corresponding electric audlofrequency oscillations and actuate the amplifier microphone 44 to produce corresponding amplified oscillations which are delivered to the energizing coilV 36 of the bone conduction receiver which is held pressed against the bones and transmits through the bones corresponding inertia reaction hearing inducing vibratory forces to the inner ear of the user, or his auditory center.

The actual size of the bone conduction receiver shown in Figs. 2 to 4 is only about onethird the size in which it is shown in the original drawings. Its resiliently carried vibratory core 33 is formed of a U-shaped permanent magnet and its central core piece 34 is formed of soft iron and secured as by riveting to the center of the core 33. The permanent magnet 33 is magnetlzed so that its outer arms are of one polarity and its center portion to which the core piece 34 is joined of opposite polarity.

The end surfaces of the two outer core arms of the vibratory core 33 have their outer surfaces on the same level as the pole face ofthe central core 34, their surfaces being preferably ground The armature diaphragm 32 is made of a magnetically conducting spring steel and has its center portion stiiened by integrally uniting it, as by soldering or brazing, to a heavy rigid anchoring cross bar of iron, for instance, extending transversely across the diaphragm 32.

The central portion of the armature diaphragm 32 extends over the full length of the cross bar 5I and is integrally united thereto as by soldering or brazing. The center portion of the anchor bar 5| is provided with a threaded hole 2|8 in which is threadedly mounted the armature core 3| having at its exterior end a. slot for turning it to adjust the distance of its pole face from the pole face of the core piece 34.

'I'he end portions of the cross bar 5| areundercut and fit the side walls of a groove provided in the base 23 of the receiver, which may be molded of a synthetic resin. The cross bar 5| is tightly clamped to the base 23 by four screws 53 which are screwed into metal anchorers 54, imbedded within the base. An opening in the base 23 is enclosed by sealing plug 55 to give access to the groove of the armature 3| for adjusting the gap. Once the adjustment is made, the armature 3| may be locked `in place, for instance, by a lock member 56. v To the ends of the armature diaphragm 32 are united, as by soldering or brazing, reinforcing plates 51 so as to provide a solid clamping joint between the arms of the vibratory core 33 and the ends of the armature diaphragm 32.

However. the gap adjustment may be made before the armature supporting bar 5| is clamped to the base and the base may be made with a solid outer surface.

The head band 2| has a detachable universal joint connection with the cover 24. A socket 56 with a lock spring 59 arranged similar to a familiar snap fastener is embedded in the wall of the cover 24, and a shank 60 extending from the head band has a ball-shaped end which may be inserted into the socket to form with it a detachable universal joint connection. This universal joint connection assures that, when the head band 2| presses the receiver casing 20 against the bones, the contact surfaces of the receiver will automatically adjust itself to secure an efficient coupling engagement with the bones in a stableequilibrium coupling position.

Instead of a head band, any other suitable arrangement for coupling the receiver structure to the bones may be used.

In manufacturing the bone conduction receiver of Figs. 2 to 4, the vibratory core 33 with the coil 36 and the armature diaphragm 3|32 with the cross bar 5| may be assembled as a self-contained unit and the gap between the armature 3| and the core piece 34 adjusted by turning the armature 3| until its pole face contacts with the core piece 34. Thereupon the armature 3| is turned back on its thread until a magnetic gap of the desired small length is provided between the adjacent pole surfaces and the armature 3| is locked in place. In this adjusted position the assembled vibrator structure may be tested and after final adjustment clamped to the .base 23.

A practical bone conduction receiver constructed as shownv in Figs. 3 to 4, with the following principal dimensions, will give satisfactory results: Permanent magnet core of a total outer length of 1"; a core thickness of a core height of about 1/4"; a core width of about a center core diameter of about .l"; and a diaphragm thickness of about .014". The magnetic gap is of the order of one thousandth of an inch. The vibratory permanent magnet core and the center core of the dimensions given above, have a mass of about 8 grams. The foregoing data show that a satisfactory bone conduction receiver of the invention, suitable for inconspicuous wear by the ,user, may be constructed with a driving vibratory portion having an overall mass which is only a small fraction of the mass of the head.

Because of the relatively large mass of the head, the bone-coupled driven portion of the receiver will under the action of the vibratory forces induced by audio-frequency oscillations have only an imperceptible vibratory movement and will lbe practically stationary while the resiliently carried driving vibratory mass portion will be subjected to audio-frequency accelerations. As a result of this vibratory movement, relatively large reactive forces will be imparted by the mass of the resiliently carried vibratory driving core to the bones of the head, transmitting thereto vibrations of small amplitude and large force suicient to convey by bone-conduction speech and music to the auditory center oi' the head. The magnetic gap is made very small, of the order of a mil or less, thereby securing a high negative stiffness. The armature diaphragm 32 is made of suilcient cross section to permit flow of a strong permanent flux through the gap and also to permit inducing strong alternating uxes through the magnet gapby the action of the sound-frequency current oscillations` passing through the actuating coil. The stiffness of the armature diaphragm is made large enough to overcome the negative stiilness of the magnetic fluxand secure stable vibrations under the action of the fluctuating magnetic eld in the gap.

By making the joint between the diaphragm 32 and the bar 5l by which it is held clamped to the base solid and firm. as by soldering, the

center portion of the diaphragm strip does not participate in the vibratory movement of the lateral diaphragm portions, eliminating distortion that might occur otherwise. By providing at the ends of the diaphragm 32 reinforcing strips I1 which are integrally united with the diaphragm, disturbances due to non-uniform clamping of the diaphragm ends are prevented, eliminating distortion.

The high negative stiiness secured by the small magnetic gap enables-the use of a relatively thick diaphragm 32 having sufficient cross section for carrying the flux while at the same time making its effective stiffness opposing the negative magnetic stiffness suiliciently small to operate with a. resonance frequency at which good response is secured over a large sound-frequency range.

In the electromagnetic bone conduction receiver described in connection with Figs. 2 to,4, the relatively large resiliently carried vibratory mass of the receiver is utilized to produce the inertia reaction forces required for imparting hearing by bone conduction and a very stiff spring member is utilized to carry the driving vibratory mass so as to give a resonance frequency which assures a good response over the speech frequency range; The use of such stiff spring makes possible the operation of the electromagnetic vibrating structure with an extremely small magnetic gap distance at which the high ux densities and large magnetic forces in the gap do not produce fringing or freezing of the pole faces bordering the gap. Such small gaps are made possible by the utilization of the coupled vibratory portion of the vibrating structure as casing which protects the resiliently carried vibratory mass against any disturbance by external forces. This combination of elements assures an extremely efficient vibratory structure and. makes possible the development of relatively large power in a very small receiver unit.

In the bone conduction hearing device described above, the large-intensity, small-amplitude forces required for inducing intelligible hearing of Speech by bone conduction are produced with a lsmall vibratory unit formed of a driven vibratory portion having a resilient junction carrying a drivingvibratory mass portion that has only a small fraction of the mass of the head, and a contact wall suiiiciently large and so arranged opposite the driving vibratory portion as to maintain the vibratory unit in a stable-equilibrium coupling position on the bone with a relatively small external force and couple by the resilient junction the small mass of the driving vibratory portionwith the large mass of the head into a. vibrating system having a resonance frequency which gives a good response in the speech frequency range and produces by electric speech frequency oscillations accelerations of the resiliently carried mass which impart to the bone the hearing inducing vibratory energy.

Such arrangement makes it possible to use only a small external coupling force for holding the vibratory unit in its most efllcient hearing induc- QLS l ing coupling position, particularly since the iny ertia reaction forces which act in a general direction perpendicular to the contact wall assist in positioning the vibratory unit along the bone. As a result, no precautions are required to prevent tipping of the bone receiver unit and a comfortable head-band which is attached to the vibratory Vunit through a loose pivotal universal lioint connection exerting the small external coupling force makes possible the automatic positioning of the vibratory unit in its most eilicient, stable-equilibrium, vibration-transmitting coupling position along the bone, and this efllcient coupling engagement is not upset or disturbed by irregularities of the external coupling force.

In Figs. 5 to '1 is shown a bone conduction receiver of the invention constructed with a cantilever-type vibratory structure for producing the inertia reaction forces required for inducing hearing by bone conduction. It comprises a vibratory casing, formedr of a rigid base and a cover 1l, held pressed against hearing inducing bones 22 by a head band 2i engaging a channel member formed in the cover 1I. The casing lll- 1I is a pakt of a vibratory structure of the cantilever-type formed of a U-shaped permanent magnet core 12 resiliently carried by a spring 13 clamped to a block 14 extending from the base 10, and pole pieces 15 extending from the arms of the magnet core 12 to form magnetic gaps with a magnetic armature core 16 clamped to the base of the casing. A vibratory motion is produced between the resiliently carried vibratory magnet core 12 and the armature 16 with its casing 1li- 1I by actuating the vibratory structure with audio-frequency current oscillations supplied to actuating windings mounted on the pole pieces 15 through the terminal bushings 18 provided in a terminal block extending from the base 10.

Since the bone-coupled base 10 resists motion and the resiliently carried driving vibratory core 12 has a substantial mass lrelatively large inertia reaction forces will be exerted by the vibratory core 12 on the armature 16 and therethrough over the casing to the bones for inducing hearing by bone conduction.

In order to -secure efiicient operation of the vibratory structure with a very tiny gap of.the order of one thousandth of an inch or less, the spring 13 has a longitudinal slot for permitting adjustment of the position of the resiliently carried vibratory magnet core 12 on the spring 13 so as to assure operation at a minimum gap distance between the pole faces of the pole pieces 15 and the armature 16 without causing fringing of the adjacent pole faces.

In Figs. 8-10 is shown a bone conduction receiver embodying a balanced magnetic vibratory structure for producing the inertia reaction hearing-inducing vibrations.

It comprises a vibratory casing formed of a base 80 and a cover 8l held pressed against hearing inducing bones 22 by a head band 2l having a universal joint connection with the cover 8|, as itil the bone receiver of Figs. 2 to 4. The casing Sil-8| is a part of a vibratory structure formed of a magnetic armature core 82 having its opposite ends clamped to two base projections 83 and resiliently carrying on its magnetic diaphragm extensions 84 a vibratory balanced magnetic core system formed of magnetic core blocks 81 and core bars 85 having central core pole pieces 86 facing the opposite faces of the armature BZ'to form therewith two magnetic gaps.

a1,oso

The magnetic system ismagnetized so that the two pole pieces 88 are of opposite polarity and pass a permanent magnetic ilux from one pole piece 88 across the armature 82 and its two gaps `to the other pole piece 86, the path of the permanent i'lux being completed by the magnetic core blocks 81 through which the ends of the opposite magnet bars 88 are clamped to the reinforced ends of the diaphragm 84 without using the diaphragm extensions v84 for carrying the permanent iiux.

n each pole piece 88 are mounted coils oi' actuating windings 88 which are supplied with electric audioi'requency oscillations through terminal bushings 88 mounted on a terminal block extending from the base 88. The two coils 88 are so connected that when actuated by audiofrequency current oscillations .the ilux in one magnetic gap is reduced while it is increased in the other gap, the diaphragm extensions 86 serving as return paths for the alternating iiux. Since the armature 82 is rigidly clamped to the base 88, the audioirequency flux variations in the two armature gaps will produce a vibratory motion between the resiliently carried vibratory core bars 8l and the amature 82 and the inertia reaction of the resiliently carried vibratory mass will exert on the armature 82, and therethrough, by way of the casing wall, on the bones of the user, inertia reaction forces which induce hearing by bone conduction.

To secure emcient ,operation of the magnetic vibrating structure, the core-pole pieces l86 are threadedly mounted in holes of the magnet bars 88 so as to make possible adjustment of the gaps between the pole faces oi the core pieces 86 and the gap faces of the armature 82 at which the gaps will be a minimum without causing fringing of the adjacent pole faces during the operation of the receiver. Lock nuts provided on the exterior threaded ends oi.' the core pole pieces 88 permit locking of the pole pieces 86 in their adjusted positions.

By using a balanced magnetic system in the bone conduction receiver of the invention, of the type shown in Figs. 8 to 10, even harmonic disiortion'is eliminated and objectionable saturation of the nuxpaths is avoided.

Since the permanent iiux acting on the opposite pole faces of the amature is balanced, the armature diaphragm is not subjected to any permanent deflection. Furthermore,'the maximum amplitude of the vibrations between the armature and the vibratory core is limited by the small magnetic gaps of the order of one thousandth of an inch on the opposite sides of the armature.

Accordingly, flexing oi.' the armature diaphragm beyond its elastic limit is prevented, and even if the receiver is dropped, and the momentum of the .heavy vibratory mass tends to impart a large deilection to the armature diaphragm, this deection will be limited by the small gaps on the opposite sides oi' the amature toa value at which the elasticity oi' the diaphragm will laummatically restore the normal gap spacing.

As a result, the receiver may be dropped without damage, and it may be operated with smaller gaps than receivers without balanced magnetic core systems, thereby increasing its eiliciency.

In Figs. 11 and 12 are shown two other exempliiicatlons of an inertia reaction bone conduction receiver of the invention. In the arrangement of Fig. 1l, a receiver housing formed of a casing 86 and a top wall 8| has clamped to the top wall 8l an extension of a magnetic core piece 82 on which is mounted a magnetic diaphragm 88 resiliently carrying a vibratory U-shaped magnet core 8l which has a central pole face forming a magnetic gap with the pole face of the core piece 82. The vibratory structure is actuated by a coil 86 mounted on the core piece 82 clamped to the top 8| of the casingto produce under the action of audiofrequency currents a vibratory motion between the resiliently carried vibratory core 86 and thecore piece 82. As a result, the inertia reaction of the resiliently carried vibratory core exerts hearing inducing vibratory forces on the core piece 82 and therethrough, over the casing 88 on the hearing-inducing bones engaged by the casing.

The casing of the bone conduction receiver shown in Fig. 1.1, is illustrated in the form of a .bridge member of a spectacle frame and its exterior walls are shown curved to form a concave contact surface for securing intimate coupling engagement with the bones 22 of the nose and securean eiiicient transmission of the hearing-inducing vibratory energy from the receiver casing to the bones.

In the arrangement oi' Fig. 12 is shown an inertia reaction bone conduction receiver of the invention having an electromagnetic vibrating .structure similar to that shown in Figs. 2 to 4. It

comprises a vibratory magnetic core 33 resiliently carried by an armature diaphragm 32 which is clamped to a wall of an enclosing casing 86 having a projecting contact member 81 with a curved concave contact surface held in engagement with hearing inducing bones 22 of the user. This bone conduction receiver is likewise designed for mounting in a bridge member of a spectacle frame 88 forming a housing around the receiver casing 86 and supporting it between two springs 88 so as to prevent the vibrations of the receiver casing 86 which are transmitted by the contact member 81 to the bones of the nose from being transmitted to the spectacle frame 88.

The performance and the quality oi' the reproduction in the bone conduction receivers of the invention described above may be increased without increasing their weight and size by employing instead of ordinary steel diaphragms special materials of high magnetic permeability, such as Hypernik, A-metal or Permalloy. These materials have a much higher magnetic permeability than ordinarily used spring steel. They accordingly reduce the flux reluctance and enable development oi' larger iiuxes increasing thepower output of a given size and weight of structure.

In the lbone conduction receivers described above,.such high permeability materials may be used notwithstanding their relatively smaller elasticity, because the small amplitudes with which the diaphragme are required `to operate produce only small strains in such diaphragms, and thesestrains are within their elasticity limits. By using such materials for diaphragms, they may be given a relatively great thickness without unduly increasing their stiffness, thus providing a large cross vsection ofhighly permeable magnetic material for producing a large flux and providing at the same time the required elasticity for operating with a desirable degree of stillness.

The principles of the invention described above in connection with various types of electromagnetic vibrating structureswill suggest to'those skilled in the art manyother ways of making small inertia reaction'bone conduction receivers with various other types of electrically actuated vibratory structures which are generally used for constructing telephones, loudspeakers and similar acoustic devices. It is accordingly desired that the appended claims be given a broad construction commensurate with the scope of the invention within the art.

I claim:

1. In a bone conduction hearing aid device suitable for inconspicuous wear by a deafened person, an elastically deformable vibratory mem- 10 ber having two vibratory portions and means for actuating said vibratory memberA with electric oscillations substantially throughout the speech frequency range for producing corresponding vibrations of said vibratory portions, one of said i6 vibratory portions having a contact surface arranged to be held coupled under pressure to hearing inducing bones of the user and resiliently carrying the other of said vibratory portions, the resiliently carried vibratory portion having sumcient mass and exerting under the action of the elastic oscillations suillcient inertia reaction forces upon the coupled vibratory portion and therethrough upon the coupled bones of the user for,

imparting thereto the vibratory energy required 26 for conducting corresponding vibrations through the bones to the inner ear ofthe user and induce intelligible hearing.

2. In a bone conduction hearing device suitable for inconspicuous wear by a user, a vibratory 30 structure having a driving magnetic core member anda driven magneticcore member resiliently joined into a magnetic ilux path including a gap,

means for holding said driven core member coupled under pressureto hearing inducing bones of the user outside the ear canal and carrying said .driving core member in a vibrating condition, and

windings interlinked with vsaid ux path for actuating said vibratory structure with electric oscillations of the principal audible frequency range 0 to produce corresponding vibrations of said core members across said gap, said driving core member having a suillciently large mass and exerting under the action of the electric oscillations sumcient inertia reaction forces upon said driven core 46 member and therethrough upon the coupled bones for imparting thereto the vibratory energy required for conducting corresponding vibrations through the bones to the inner ear and induce intelligible hearing. y'

60 3. The method of enabling a deafened person to hear speech through bone conduction by imparting audio-frequency vibrations to a bone of the massive head body surrounding his inner ears which resides in so resiliently carrying in a vibra- '65 tory condition and in a stable-equilibrium coupling position on the bone a vibratory portion having a mass that is smaller than about two hundred grams and only a small` fraction of the Vmass of the head body but greater than about four 50 grams that the large mass of the body and the small mass of the resiliently carried vibratory portion form a. vibrating system having a res'onance frequency which gives a good response in the speech frequency range, and accelerating the resiliently carried vibratory portion relativeto the bone with electric oscillations of the principal speech frequency range so as to produce by the acceleration of the resliently carried vibratory mass portion inertia reaction forces which impart to the bone the vibratory energy required for conducting corresponding vibrations of relatively large intensity and small amplitude through the bones to the inner ear and induce intelligible u hearing of the speech.

4. The method of enabling a deafened person to hear speech through bone conduction by imparting audio-frequency vibrations to a bone of the massive head body surrounding his inner ears which resides in so resiliently carrying in a freely 5 vibratory condition and in a stable-equilibrium coupling position on the bone a vibratory electro- `magnetically actuated portion having a mass that 'iis smaller than about two hundred grams and only a small fraction of the mass of the head body l0 but greater than about four grams that the large mass of the body and the small mass of the resiliently carried vibratoryportion form a vibrating system having a resonance frequency which gives a good response in the speech frequency range, l5 and accelerating the resiliently carried vibratory portion relative to thebone with electric oscillations of the principal speech frequency range so as to produce by the acceleration of the resiliently carried vibratory mass portion inertiav reaction 20 forces which impart to the bone the vibratory energy required for conducting corresponding'vlbrations of relatively large intensity and small amplitude through the bones to the inner ear and induce intelligible hearing of the speech. 25

5. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sulciently light and small for comfortable and substantially' inconspicuous wear coupled to a hearing inducing bone outside the ear canal of 30 the massive body of the head surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about three grams, which is only a small fraction of the mass of said body; a driven bone-coupling $6 vibratory portion having a resilient Junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction into a vibratory 40 system; said vibratory unit having a wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sufllciently large and so arranged thereunder as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone' under a relatively small external force for eiliciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stillness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sufilciently large and subjected by the oscillations to suillcient acceleration relative to the bone so that the driving vibratory portion exerts inertia reaction forces in a e5 general direction toward the wall portion surface required for imparting to the driven vibratory portion and therethrough to the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction.

6. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suflciently light and small for comfortable and substantially inconspicuous wear coupled to a 75 hearing inducing bone outside the ear canal of the massive body of the head surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about three grams, which is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient Junction into a vibratory system; said driven vibratory portion forming a part of a wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, suiliciently extended and so arranged thereunder as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external force for efficiently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actua'ling said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a. good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sufilciently large and subjected by the oscillations to suillcient acceleration relative to the bone so that the driving vibratory portion exerts inertia reaction forces in a general direction toward the wall portion surface required for imparting to the driven vibratory portion and therethrough to A the bone the vibrations of large intensity and small ampliude required for inducing intelligible hearing of speech by bone conduction, said wall portion forming part of a casing enclosing said driving vibratory portion.

7. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suillciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the ear canal of the massive body of the head surrounding' the inner ears of the user comprising: a driving vibratory portion having a mass greater than about three grams, which is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junciion carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction in to a vibratory sysem; said vibratory unit having a wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sulficiently large and so arranged thereunder as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external force for emciently transmitting to the bone the vibratory forces exer'ed by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vilzratory portion and the stiifness of its resilient Junction being so proportioned and so arranged in the vibratory unit that the vibratory ksystem which they foi-m with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sufficiently large and subjected by the oscillations to sucient acceleration relative to the bone so that the driving vibratory portion exerts inertia reaction forces in a general direction toward the wall portion surface required for imparting to the driven vibratory portion and therethrough to the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction, and external supporting means having a ,surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a mass greater than about four grams,

and smaller than, about two hundredgrams so that it is only a small fraction of the mass of said body;A a driven bone-coupling vibratory magnetic core member having a resilient junction carrying said driving core member in a vibratory condition to form therewith a magnetic path including a gap and arranged to op.- eratively couple said small-massdriving member with the large-mass body by the lresilient junction into a vibratory system; said vibratory unit hav# ing a substantially rigid wall portion sumciently large and so arranged under and relatively to the' driving vibratory member as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for efficiently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means including windings for actuating said vibratory core members with electric oscillations throughout the prin cipal speech frequency range for producing corresponding vibrations of said vibratory mem-- bers across said gap; the mass of the driving vibratory member and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory member is sumciently large and subjected by the oscillationsto suilcient acceleration relative to the bone so that the driving vibratory member exerts on the driven vibratory member and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction.

9. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sufficiently light and small for comfortable and substantially inconspicuous wear coupledv to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a mass greater than about four grams,

and smaller than about Vtwo hundred grams so.,

that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory magnetic core member having a resilient junction carrying said driving core member in a vibratory condition to form therewith a magnetic path including a gap and arranged to operatively couple said small-mass driving member with the large-nass body by the resilient junction into a vibratory system; said vibratory unit having a substantially `-rigid wall portion suiliciently large and so arranged under and relatively to the driving vibratory member as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for emciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and, means including windings for actuating said vibratory core members with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory members across said gap; said vibratory .unit having a closure portion arranged to protectively isolate from the exterior the space across which said vibratory members vibrate; the mass of the driving vibratory member and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range. and that the mass of the resiliently carried driving vibratory member is sumciently large and subjected by the oscillations to suilicient acceleration relative to the bone so that the driving vibratory member exerts on the driven vibratory member `and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction.-

10. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suiciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about two hundred grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said drivingportion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction into a vibratory system; said vibratory unit having a substantially rigid wall portion sufliciently large and so arranged under and relatively to the driving vibratory portion as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for efficiently transmitting to the bone the vibratory forces exerted by the vibratory unit; `and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stiiness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, andy that the mass of the resiliently carried driving vibratory portion is suiliciently large and subjected by the oscillations to suiiicient acceleration relative'to the bone so that the driving to a hearing inducing bone outside the ear canal of the massive body of the Ahead surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about two .hundred grams so that it is only a small fraction of the mass of said body; a driven bonecoupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction into a vibratory system; said vibratory unit having a substantially rigid wall portion sufliciently large and so arranged under and relatively to the driving vibratory portion asv to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for efliciently transmitting to the" bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech Ifrequency range for producing corrponding vibrations of saidv vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stillness of its resilient junction being so proportioned and so arranged in the vibratory unit' that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sumciently large and subjected by the oscillations to suilcient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction, and external supporting means having a pivotal joint connection with said vibratory unit for holding said wall portion cooperatively coupled to the bone.

l2. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sufficiently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about two hundred grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction into a vibratory system; said vibratory unit having a substantially rigid wall portion suiliciently large and so arranged under and relatively to the driving vibratory portion as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for eiliciently transmitting to the bone the vibratory 7| forces exerted by the vibratory unit: and means for actuating r.id vibratory portions with electric oscillationsthroughout the principal speech frequency range for producing corresponding vibrations of said vibratory vportions across the space between said vibratory portions; said vibratory unit having a closure portion arranged to protectlveiy isolate from the exterior the space across which saidvibratory portions vibrate: the mass ol the driving vibratory portion and the .stiffness of its resilient iimction being so proportioned and so arranged in the vibratory unit that the-vibratory system which they` form with the mass oi' said body has a resonance yfrequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is suillciently large and subjected by the oscillations to suflicient'acceleration relative tc the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech bybone conduction.

i3. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sufficiently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about one hundred and sixty grams so that it is only a small fraction of the mass of said body; a driven bone-'coupling vibratory portion having a resilient Junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction into a vibratory system; said driven vibratory portion forming a part of a wall portion suillciently extended and -so arranged under and relatively to the driving vibratory portion as to maintain said vibratory unit in a. stable equilibrium coupling position on the boneunder a relativelyv small external coupling force for efiiciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions;the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good .vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sumeienuy large and subiected by the osculations to sufficient acceleration relative to the bone so that' the driving vibratory portion exerts inertia reaction forces required for imparting to the driven vibratory portion and therethrough to the bone vibrations of large intensity and small amplitude required for indlming intelligible hearing of speech by bone conduction.l

i4. -In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sufficiently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the ear canal of the massive body of the head surroundingtheinnerearsoftheusercomprlsing: a driving vibratory portion having a mass greater than aboutAfour grams, and smaller than about one hundred and sixty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient Junction can'ying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient Junction into a vibratory system; said driven vibratory portion forming a part of a wall portion suiliciently ,A extended and so'arranged under and relatively to the driving vibratory portion as to maintain said vibratory unit in a stable-equilibrium coupling position on the boneunder a relatively small external coupling force for efficiently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations 'of said vibratory portions across the space between said vibratory portions the mam of the driving vibratory portion and the stinness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the large mass of said body has a resonance frequency 'which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sumciently large and subjected bythe oscillations to sufllcient acceleration relative to the bone so that the driving vibratory portion exerts inertia reaction forces required for imparting to the driven vibratory portion and therethroughto the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction, and external supporting means having a pivotal Joint connection with said vibratory unit for holding said wall portion cooperatively coupled to the bone.

15. In a wearable bone conduction hearing aid device, a vibratory unitdes'igned and arranged to be sufficiently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams. and smaller than about one hundred and sixty grams so that it is only a small fraction of the mass of said body: a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arrangedto operatively couple said small-mass driving portion with the large-mass body by the resilient Junction into a vibratory system:said driven vibratory portion forming a part of a wall portion sumciently extended and so arranged under and relatively to theA driving vibratory portion as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for efilciently transmitting to the bone the vibratory forces exerted by the vibratory unit: and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding v1- bations of said vvibratory portions'acrosathe space between said vibratory portions: said vibratory unit having a closureportion arranged to protectively isolate from the exterior the space across which said vibratory portions vibrate; the mass of the driving vibratory portion and the stiifne of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sufllclently large and subjected by the oscillations to sufllcient acceleration relative to the bone so that the driving vibratory portion exerts inertia reaction .forces required lfor imparting to the driven vibratory portion and therethrough to the bone vibrations of large intensity and small amplitude required .for inducing intelligible hearing of speech by bone conduction.

16. In a wearable bone conduction hearing aid device, a vibratory unit designed and'arranged to be sufnciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a mass greater than about four grams, and smaller than about one hundred and sixty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory magnetic core member having a resilient junction carrying said driving core member in a vlbratory condition to form therewith a magnetic path including a gap and arranged to operatively couple said small-mass driving member with' the large-mass body by the resilient junction into a vibratory system; said driven vibratory member forming a part of a wall portion suiilciently extended and so arranged under and relatively to the driving vibratory member as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for eiliciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means including windings for actuating said vibratory core members with electric oscillations lthroughout the principal speech frequency range for producing corresponding vibrations of said vibratory members across said gap; the mass of the driving vibratory member and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory member is sufficiently large and subjected by the oscillations to sumcient acceleration relative to the bone so that the driving vibratory member exerts inertia reaction forces required for imparting to the driven vibratory member and therethroughy to the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction.

17. In a wearable bone conduction hearing aid l device, a vibratory unit designed and arranged to be suillciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a mass greater than about four grams, and smaller than about one hundred and sixty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory. magnetic core member having a resilient junction carrying said driving `core member in a vibratory condition to form therewith a magnetic path including a gap and arranged to operatively couple said small-mass driving member with the large-mass body by the resilient junction into a vibratory system; said driven vibratory member forming a part of a wall portion sumcientlyextended and so arranged under and relatively to the driving vibratory member as to maintain said vibratory unit in a stable-equilibrium coupling position on l the bone under a relatively small. external coupling force for efilclently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means including windings for actuating said vibratory core members with electric oscillations throughout the principal speech frequency range for producing coresponding vibrations of said vibratory members across said gap; said vibratory unit having a closure portion arranged to protectively isolate from the exterior the space across which said vibratory members vibrate; the mass of the driving vibratory member and the stiffness of its resilient junction being so proportioned and so arranged ln the vibratory unit that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory member is sufllciently large and subjected by the oscillations to sufhcient acceleration relative to the bone so that the driving vibratory member exerts inertia reaction forces required for imparting to the driven vibratory member and therethrough to the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction.

18. In a wearable bone conduction hearing aid device, a vibratory structure designed and arranged to be suiliclently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, andsmaller than about one hundred and twenty grams so that it is only a small fraction of the massof said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction into a vibratory system; said driven vibratory portion forming a part of a wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater. sumciently large and so arranged opposite thereto as to maintain said vibratorystructure in a stableequilibrium coupling position on the bone under a relatively small external coupling force for eillciently transmitting to the bone the vibratory forces exerted by the vibratory structure; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and. the stiffness of its resilient junction being so proportioned and so arranged in the vibratory structure that the vibratory system which they `formwith the large mass of said body has a resonance fre- Loco quency which gives a good vibratory response in the speech irequencyrange, and that the mass ci' the resiliently carried driving vibratory portion is sumciently large and subjected by the oscillations to sumcient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the boneinertia reaction forces required for inducing intelligible hearing of speech by bone conduction.

19. In a wearable bone conduction hearing aid device, a vibratory structure designed and arranged to be suiiiciently light and small forcomfortable and substantially inconspicuous wear coupled to a healing inducing bone lof the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and

smailer than about one hundred and twenty1 grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient Junction into a vibratory system; said driven vibratory portion forming a part of a wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibralate from the exterior the space across which said vibratory portions vibrate; the mass of the driving vibratory portion and thel stillness of its resilient junction being so proportioned and so arranged in the vibratory structure that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sum4- ciently lage and' subjected by the oscillations to sumcient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reaction forces required for inducing intelmass of said body; a driven bone-coupllng vibra-A tory magnetic core member having a resilient Junction carrying said driving core member in a vibratory condition to form therewith a magnetic path including a gap and arranged to operatively couple said small-mass driving member with the large-mass body by the resilient Junction into a vibratoryl system; said driven vibratory portion forming part of a substantially rigid wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sufiiciently large and so .arranged opposite thereto as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for emciently transmitting to the bone the vibratory forces .exerted by the vibratory `unit; and means including windings for actuating said vibratory core members with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory members across said gap; the mass of the driving vibratory member and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the large mass of said body has a resonance frequency which gives `a good vibratory response in the speech frequency range, and that the mass of the resiliently carried diving vibratory member is suf- -ciently large and subjected by the oscillations to sutilcient acceleration relative to the bone so that the driving vibratory member exerts inertia reaction forces required for imparting to the driven vibratory member and therethrough vto the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction.

21. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suillciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body ,surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a mass greater than about four grams, and smaller than about one hundred and twenty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory magnetic core member having a resilient junction carrying said driving core member in a vibratory conditionA to form therewith a magnetic path including a gap and arranged to operatively couple said small-mass driving member with the large-mass body by the resilient junction into a vibratory system; said driven vibratory portion forming part of a substantially rigid wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sufiiciently large and so arranged opposite thereto as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for emciently transmitting to the bone the vibratory forces exerted by the vibratory unit; andmeans including windings for actuating said vibratory core members with electric oscillations throughout the principal speech` frequency range for producing corresponding vibrations of said vibratory members across said gap; said vibratory unit having a closure portion arranged to protectively isolate from the exterior the space` across which said vibratory members vibrate; the mass of the driving vibratory member and the stiffness of its resilient junctionbeing so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resilientiy carried driving vibratory member is suillciently large and subjected by the oscillations to sumcient acceleration relative tb the bone so that the driving vibratory member exerts inertia reaction forces required for imparting to the driven vibratory member and therethrough to the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction.

22. In a wearable bone conduction hearing aid device, a vibratory structure designed and arranged to be suillciently light and small for comortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about one hundred grams so that it is only a small fraction of the mass of said body: a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion-with the large-mass body by the resilient junction into a vibratory system; said driven vibratory portion forming a part of a wall' portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sumciently large and so arranged opposite thereto as to maintain said vibratory structure in a stableequilibrium coupling position onthe bone under a relatively small external coupling force for efficiently transmitting to the bone the vibratory Vforces exerted by the vibratory structure; and

means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions;-

the mass of the driving vibratory portion andv the stiness of its resilient junction being so proportioned and so arranged in the vibratory structure that the vibratory system which they form with the large mass o! said body has a resonance frequency which gives a good vibratory response in the speech frequency range. and that the mass of the resiliently carried driving vibratory portion is sufllciently large and subjected by the oscillations to sumcient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction.

23. The method of enabling a deafened person to hear speech through bone conduction by imparting audio-frequency vibrations to a bone of the massive head body surrounding his inner ears which resides'in so resiliently carrying in a vibratory condition and in a stable-equilibrium coupling position on the bone a vibratory portion having a mass that is smaller than about one hundred and twenty grams and only a small fraction of the mass oi' the head body but greater than about four grams that the large mass of the body and the small mass of the resiliently carried vibratory portion form a vibrating system having a resonance frequency which gives a good response in the speech frequency range, and accelerating the resiliently carried vibratory portion relative to the bone with electric oscillations of the principal speech frequency range so as to produce by the acceleration of the resiliently carried vibratory mass portion inertia reaction forces which impart to the bone the vibratory energy required for conducting corresponding vibrations ot relatively large intensity and small amplitude through the bones to the inner ear and induce intelligible hearing of the speech.

24; The method of enabling a deafened person to hear speech through bone conduction by imparting audio-frequency vibrations to a bone of the massive head body surrounding his inner ears which resides in so resiliently carrying in a vibratory condition and in a stable-equilibrium coupling position on the bone a vibratory portion having a mass thatV is smaller than about sixty grams and only a small fraction of the mass of the head body but greater than about four grams that the large mass .of the body and the small mass of the resiliently carried vibratory portion form a vibrating system having a resonance i'requency which gives a good response in the speech frequency range, and accelerating the resiliently carried vibratory portion relative to the bone with electric oscillations of the principal speech i'requency range so as to produce by the acceleration of the resiliently carried vibratory mass portion inertia reaction forces which impart to the bone the vibratory energy required for conducting corresponding vibrations oi relatively large intensity and small amplitude through the bones to the inner ear and induce intelligible hearing of the speech.

25. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suihciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the ear canal oi' the massive body of the head surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about three grams, which is only a small fraction oi' the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition, and a substantially rigid contact wall with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sufilciently large and so arranged opposite thereto as to maintain said vibratory unit in a stable-equi librium coupling position on the bone under a relatively small external coupling force for coupling the small-mass of the driving vibratory portion with the large-mass body by the resilient junction into a vibratory system and for emciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the f space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sufficiently large and subjected by the oscillations to sufficient acceleration relative to the bone so that thedriving vibratory portion exerts inertia reaction forces in a general direction toward the contact wall surface required for imparting to the driven vibratory portion and therethrough to the bone vibrations oi' large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction.

26. In a wearable bone conduction hearing aid device. a vibratory unit designed and arranged to be suillcientiy light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the ear canal of the massive body of the head surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about three grams, which is only a small fraction of the mass of said body; a driven bone-coupling vibratory portionr having a resilient junction carrying said driving portion in a vibratory condition, and a substantially rigid contact wall with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sufciently large and so arranged opposite thereto as to maintain said vibratory unit in a stableequilibrlum coupling position on the bone under a relatively small external coupling force for coupling the small-mass of the driving vibratory portion with the large-mass body by the resilient junction into a vibratory system and for emciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations oi' said vibratory portions across the space between said vibratory portions: said vvibratory unit having a closure portion arranged to protectively isolate from the exterior the space across which said vibratory portions vibrate; the mass of the driving vibratory portion and the stiness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibm tory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range. and that the mass of the resiliently carried driving vibratory portion is sufilciently large and subjected by the oscillations to sumcient acceleration relative to the bone so that the driving vibratory portion exerts inertia reaction forces in a general direction toward the contact wall surface required for imparting to the driven vibratory portion and therethrough to the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction.

27. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suillciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the earcanal of the massive body of the head surrounding the inner ears of the user comprising:A a driving vibratory portionhaving a mass greater than about three grams, which is only a small fraction of the mass of" said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition, and a substantially rigid contact wall with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sufllciently large and so arranged oppo site thereto as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for coupling the'small-mass oi the driving vibratory portion with the large-mass body by the resilient junction into a vibratory system and for emciently transmitting to the bone the vibratory forces exerted by the vibratory unit: and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of saidy vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with themassofsaidbodyhas a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is su'fficiently large and subjected by the oscillations to suillcient acceleration relative to the bone so that the driving vibratory portion exerts inertia reaction forces required for imparting to the driven vibratory portion and therethrough to the bone vibrations of large intensity and small amplitude required for inducing intelligiblehearlns of speech by bone conduction. and external supporting means having a universal Joint connection with said vibratory unit for holding said contact coupled to the bone.

28. In a wearable bone conduction hearing ai device, a vibratory unit and arranged to be sufiiciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion 'havinga' mass greater than about four grams, 'and smaller than about eighty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couplesaid smallmass driving portion with the large-mass body by the resilient junction into a vibratory system; said driven vibratory portion 'forming a part of a wall portion suillciently extended and so arranged under and relatively to the driving vibratory portion as tomaintain said vibratory unit in a stableequilibrium coupling position on the bone under a relatively small external coupling force for eiliciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech ,irequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the of its resilient junction being so proportioned and so arranged in the vibratory unit that`the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sumciently large and subjected by the oscillations to suilicient acceleration relative to the bon'e so that the driving vibratory portion exerts inertia reaction forces required for l imparting to 'f the driven lvibratory portion and therethrough to the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction. 1 i

29. 1n a wearable bone conduction hearing aid device, a vibratory. unit desisned and arranged to be sufilciently light and small for comfortable and substantially incons'picuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams. and smaller than about iiftygramasothatitisonlyas'mallfractionof the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction into a. vibratory system; said driven vibratory portion forming a part of a wall portion sufliciently extended and so arranged under and relatively to the driving vibratory portion as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively Vsmall external coupling force for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions acros -the space between said vibratory portions; the

mass of the driving vibratory portion and the stillness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory systemA which they form with the massv of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sumciently large and subjected by the oscillationsto suilicient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction.

30. Inla wearable bone'conduction hearing aid device, a vibratory structure designed and arranged to be suiilcientlyiight and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding theinner ears oi' the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller thanaboutthirtygramssothatitisonlya small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilforming a part of a wall portion with lateral dil mensions of the order of the lateral dimensions of the driving vibratory portion or greater, suiiiciently large and so arranged opposite thereto as to maintain said vibratory structure in a stableequilibrium coupling position on the bone under a relatively small external coupling force for eiliciently transmitting to the bone the vibratory forces exerted by the vibratory structure; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory structure that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resillently carried driving vibratory portion -is suillciently large and subjected by the oscillations to sufcient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bon'e inertia reaction forces required for in- `ducing,` intelligible ,y hearing of vspeech by bone conduction.

31. Ina wearable bone conduction hearing aid device. a vibratory unit designed and arranged to be suillciently Y light and for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the ear canal of the massive body of the head surrounding the inner ears of thequ'ser comprising: ardriving vibratory portion having a mass greater than about three grams, which is only a small fraction of the f mass of said body; a driven bone-coupling vibratory. portion hav-inge. resilient junction carrying said driving portion ln a yvibratory condition, and a substantially rigid contact wall with lateral dimensions of the order of the lateral dimensions of the drivingrvibratory portion or greater, sumciently large and so arranged opposite thereto as to maintain said vibratory unit in a stableequilibrium coupling position on the bone under a relatively small external coupling force for coupling the small-mass of the driving vibratory portion with the large-mass body by the resilient junction into a vibratory system and for elciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being s o proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a. good vibratory response in the speech frequency range, and that the maas of the resiliently carried driving vibratory portion is sumciently large and subjected by the oscillations to suilcient acceleration relative to the bone so that the driving vibratory portion A exerts inertia reaction forces in a general direction toward the contact wall surface required for imparting to the driven vibratory portion and therethrough to the bone vibrations of large intensity and smallamplitude required for inducing intelligible hearing of speech by bone conduction, and external supporting means having a pivotal joint connection with said vibratory unit for holding said contact wall coupled to the bone.

32. In a wearable bone conduction hearing aid device, a vibratory structure designed and arranged to be suillciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the ear canal of, the massive body of the head surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about one hundred and twenty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the largemass-body by the resilient junction into a vibratory system; said driven vibratory portion forming a part of a wall portion with lateral dimensions of the order ol' the lateral dimensions of the driving vibratory portion or greater, sumciently large and so arranged opposite thereto as to maintain said vibratory structure in a stable-equilibrium coupling position on the bone tory forces exerted by the vibratory structure; and means tor actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrationsoi' said vibratory portions across the space'between said vibratory portions; the mass of the driving vibratory portion and the stiness of its resilient junction being so proportioned and so arranged in the vibratory strucf ture that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently .carried driving vibratory portion is suiiiciently large and subjected by the oscillations to suiiicient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction, and external supporting means having a pivotal ioint connection with said vibratory structure for holding said wall portion cooperatively coupled to the bone.

33. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sumciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the ear canal of the massive body of the head surrounding the inner ears oi the user comprising: a driving vibratory portion having a mass greater than about i'oury grams, and smaller than about two hundred Brains so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said smallmass driving portion with the large-mass body by the resilient junction into a vibratory system; said vibratory unit having a'substantlally rigid wall portion suiiiciently large and so arranged under and relatively to the .driving vibratory portion as to maintain said vibratory unit in a stableequilibrium coupling position on the bone under a relatively small external coupling force for emciently transmitting to the b one the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations oi said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass oi' said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sufficiently large and subjected by the oscillations to sufficient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of sp'eech by bone conduction, and external supporting means having a universal joint connection with said vibratory vunit for holding said wall portion cooperatively coupled to the bone.

34. In a. wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sumciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone outside the ear canal of the massive body of the head surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about three grams, which is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition. and a substantially rigid contact wall with lateral dimensions of the order of the lateral dimension of the driving vibratory portion or greater, sumciently large and so arranged opposite thereto as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for coupling the small-mass of the driving vibratory portion with the large-mass body by the resilient junction into a vibratory system and for emciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass oi' the driving vibratory portion and the stiii'ness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass oi the resiliently carried driving vibratory portion is sufficiently large and subjected by the oscillations to suflicient acceleration relative to the bone so that the driving vibratory portion exerts inertia reaction forces in a general direction toward the contact wall surface required for imparting to the driven vibratory portion and therethrough to the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing, of speech bybone conduction, said contact wall being part of a casing enclosing said driving vibratory portion.

35. In a wearable bone'oonduction hearing aid device. a vibratory unit designed and arranged to be sumciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surf rounding the inner ears of the user comprising: a, driving vibratory magnetic core member having a mass greater than about four grams, and smaller than about sixty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory magnetic core member having a resilient junction carrying said driving core member in a vibratory condition to form therewith a magnetic path including a, gap and arranged to operatively couple said small-mass driving member with the large-mass body by the resilient junction into a vibratory system; said driven vibratory member formin a part of a wall portion suiliciently extendedl and sofarranged under and relatively to the driving vibratory member as to maintain said vibratory unit in a stableequilibrium coupling position on the bone under a relatively small external coupling force for emciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means including windings for actuating said vibratory core members with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of ysaid vibratory members across said gap; the mass of the driving vibratory member and the stillness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which theyformwith themassofsaidbodyhasaresonance frequency which gives a good vibratory response in the'speech frequency range. and that the mass of the resiliently carried driving vibra.-

tory member is sumciently large and subjected by the oscillations to sufllclent acceleration relative to the bone so that the driving vibratory member exerts on the driven vibratory member and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction.

36. In a wearable bone conduction hearing aid device a vibratory unit designed and arranged to be sufficiently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a mass greater than about four grams, and smallerv than about forty grams so that it is only asmall fraction of the mass of said body; a driven bone-coupling vibratory magnetic core member having a resilient junction carrying said driving core member in a vibratory condition to form therewith a magnetic path including a gap and arranged to operatively couple said small-mass driving member with the large-mass body by the resilient junction into a vibratory system; said driven vibratory member forming a part of a wall portion sufliciently extended and so arranged -under and relatively to the driving vibratory member as to maintain said vibratory unit in a stable-equilibrium coupling potion on the bone under a relatively small external coupling force for eiiiciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and

` means including windings for actuating said vispeech frequency range, and that the mass of the resiliently carried driving vibratory member is sumciently large and subjected by the oscillations to suilicient acceleration relative to the bone so that the driving vibratory member exerts inertia reaction forces required for imparting to the driven vibratory member and therethrough to f the bone vibrations of large intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction.

37. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sumciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a mass greater than about four grams, and smaller than about two hundred grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory magnetic core member having a resilient junction carrying said driving core member in avibratory condition to form therewith a magnetic path including a gap and arranged `to operatively couple said smallmass driving member with the large-mass body by the resilient junction into a vibratory system;

said vibratory unit having a substantially rigid wall portion sufliciently large and so arranged under and relatively to the driving vibratory member as to maintain said vibratory unit in a stableequilibrium coupling position on the bone under a relatively small external coupling force for eiilciently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means including windings fbr' actuating said vibratory core members with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory members across said gap; the mass of the driving vibratory member and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory member is sufiiciently large and subjected by the oscillations to sumcient acceleration relative to the bone so that the driving vibratory member exerts on the driven vibratory member and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction, said wall portion forming a part of a casing enclosing said driving vibratory member.

38. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be sufllciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about two hundred grams so that it is only a small fraction of the mass of said body; a driven bonecoupling vibratory portion having a resilient junction carrying said driving portion in a vibra' tory condition and arranged to operatively couple said small-mass driving portion with the largemass body by the resilient junction into a vibratory system; said vibratory unit having a substantially rigid wall portion suiliciently large and so arranged under and relatively to the driving vibratory portion as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for efficiently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the. vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is suflilciently large and subjected by the oscillations to sufcient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reactionY forces required for inducing intelligible hearing of speech by bone conduction, said wall portion forming a part of a casing enclosing said driving vibratory portion.

39. In a wearable bone conduction hearing aid ranged to be sufllclently light and small for comfortable and substantially inconspicuous wear coupled to a hearing 'inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater` than about four grams, and smaller than about one hundred and twenty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass driving portion with the large-mass body by the resilient junction into a vibratory system; said driven vibratory portion forming a part of a wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sufllciently large and so arranged opposite thereto as to maintain said vibratory structure in a i stable-equilibrium coupling position on the bone under a relatively small external coupling force for eihciently i transmitting to the bone the vibratory forces exerted by the vibratory structure; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across. the

space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned andso arranged in the vibratory structure that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory portion is sumciently large and subjected by the oscillations to suihcient acceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and there'- through on the boneinertia reaction forces required for inducing intelligible hearing of speech by bone conduction, said wall portion forming a part of a casing enclosing said driving vibratory portion.

40. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suiiiciently light and small for comfortable and substantially inconspicuous Wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about eighty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibrato-ry portion having a resilient junction carrying said driving portion in a vibratory condition and arranged tooperatively couple said small-mass driving portion with the:

large-mass body by the resilient junction into a vibratory system; said driven vibratory portion I forming a. part of a wall portion sutliciently extended and soarranged under and relatively to 4the driving vibratory portion as to maintain said vibratory unit in`a stable-equilibrium coupling position on the bone under a relatively small external coupling force for eiliciently transmitting to the bone the vibratoryforces exerted by the vibratory unit; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory portions across the space between said vibratory portions; the mass of. the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the large mass of said body has a resonance frequency which givesa good vibratory -response in the speech frequency range, and 'that the mass of the resiliently car-` rled driving vibratory portion is sufficiently large and subjected by the oscillations to sumcient sceeleration relative to the bone so that the driving vibratory portion exerts inertia reaction forces required for imparting to the driven vibratory portion and therethrough to the bone vibrations of largey intensity and small amplitude required for inducing intelligible hearing of speech by bone conduction, said wall portion forming a part of a casing enclosing said driving vibratory portion.

41. In a wearable bone conduction hearing aid device, a vibratory structure designed and arranged to be sufficiently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory portion having a mass greater than about four grams, and smaller than about eighty grams so that it is only a small fraction of the mass of said body; a driven bonecoupling vibratory portion having a resilient junction carrying said driving portion in a vibratory condition and arranged to operatively couple said small-mass 'driving portion with the largemass body by the resilient junction into a vibratory system: said driven vibratory portion forming a part of a wall portion with lateral dimensions of the order of the lateral dimensions of the driving vibratory portion or greater, sutllciently large and so arranged opposite thereto as to maintain said vibratory structure in a stableyequilibrium coupling position on the bone under a relatively small external coupling force for efficiently transmitting to the bone the vibratory forces exerted by the vibratory structure; and means for actuating said vibratory portions with electric oscillations throughout the principal speech frequency' range for producing correspending vibrations oi' said vibratory portions across the space between said vibratory portions; the mass of the driving vibratory portion and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory structure that the vibratory system which they form with the large mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resillently carried drivingvibratory portion is sumciently large and subjected by the osciliations to sumcientacceleration relative to the bone so that the driving vibratory portion exerts on the driven vibratory portion and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction, said wall portion forming a part of a casing enclosing said driving vibratory portion.

42. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suiliclently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing-bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a. mass greater than about four grams, and smaller than about one hundred and twenty grams so that it is only a. small fractionof the mass of said body: a driven bone-coupling vibratory magnetic core `member having a resilient junction carrying said driving core member in a vibratory condition to form therewith a magnetic path including a gap and arranged to operatively couple said smallmass driving member with the large-mass body by the resilient junction into a vibratory system; said driven vibratorymember forming a part of a wall portion sufficiently extended and so arranged under and relatively to the driving vibratory member as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone `under a relatively small external coupling force for efliciently transmitting to the bone the vibratory forces exerted by the vibratory unit: and means including windings for actuating said vibratory core members with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of saidvibratory members across said gap; the mass of the driving vibratory member and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the large mass of said bodyV has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory member is sufficiently large and subjected by 'the oscillations to sumcient acceleration relative to the bone so that,

surrounding the inner ears of the user compris-v ing: a driving vibratory magnetic core member having a mass greater than about four grams,'

and smaller than about sixty grams so that it is only a small fraction of the mass of said body; a driven bone-coupling vibratory magnetic core member having a resilient junction carrying said driving core member in a vibratory condition to form therewith a magnetic path including a gap and arranged to operatively couple said small-mass driving member with the large-mass body by the resilient junction into a vibratory system; saidv driven vibratory member forming a part of a-wall portionsuillciently extended and so arranged under and relatively to the driving vibratory member as to maintain said vibratory ,unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for eiilciently `transmitting to the bone the vibratory forces exerted by the vibratory unit; and means including windings for actuating said vibratory core members with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory members across said gap; the mass of the driving vibratory member and the stiffness of its resilient junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has aresonanoe' frequency which gives a good vibratory response quired for inducing intelligible hearing of speech by bone conduction, said wall portion forming a part of a casing enclosing said driving vibratory member.

44. In a wearable bone conduction hearing ald device, a vibratory /unit designed and arranged to be suiliciently light and small for comfortable and substantially inconspicuous Wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising: a driving vibratory magnetic core member having a mass greater than about four grams. and smaller than about two hundred grams so that it is only a small fraction of the mass of said body; a driven bonecoupling vibratory magnetic core member having a resilient junction carrying said driving core member l'n a vibratory condition to form therewith a magnetic path including a gap and arranged to operatively couple said small-mass driving member with the large-ma body by the resilient Junction into a vibratory System: said vibratory unit having a substantially rigid wall portion sumciently large and so arranged under and relatively to the driving vibratory member as to maintain said vibratory unit in a stable-equilibrium coupling position on the bone under a relatively small external coupling force for efficiently transmitting to the bone the vibratory forces exerted by the vibratory unit; and means including windings on the driving core member for actuating said vibratory core members with electric oscillations throughout the principal speech frequency range for producing corresponding vibrations of said vibratory members across said gap; 4the mass of the driving vibratory member and the stiffness of its resilient Junction being so proportioned and so arranged in the vibratory unit that the vibratory system which they form with the mass of said body has a resonance frequency which gives a good vibratory response in the speech frequency range, and that the mass of the resiliently carried driving vibratory member is sufllciently large and subjected bythe oscillations to sumcient acceleration relative to the bone so that the driving vibratory member exerts on the driven vibratory member and therethrough on the bone inertia reaction forces required for inducing intelligible hearing of speech by bone conduction.

45. In a wearable bone conduction hearing aid device, a vibratory unit designed and arranged to be suillciently light and small for comfortable and substantially inconspicuous wear coupled to a hearing inducing bone of the massive body surrounding the inner ears of the user comprising:

a driving vibratory magnetic core member having a mass greater than about four grams, and smaller than about one hundred and twenty grams so that it isonly a small fraction of the mass of said body a driven bone-coupling vibratory magnetic core member having a. resilient Junction carrying said driving core member in a yvibratory system; said driven vibratory portion forming part of a substantially rigid wall portion

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