US2410413A - Acoustic tile - Google Patents

Description

A. B. HU RLEY Nov. 5, 1946.

ACOUSTIC TILE Filed Feb. 10, 1 945 2 She ets-Sheet 1 I INVENTOR v lbert'B. Hurley r ATTORNEYS Patented Nov. 5, 1946 UNITED STATES PATENT OFFICE ACOUSTIC TILE 7 Albert B. Hurley, Huntington, N. Y. Application February 10, 1943, Serial No. 475,349 (01. 154-44) Claims.

This invention relates to an improved acoustic tile for wall structures such as ceilings and side walls for purposes of sound control.

The prime desideratum of my present invention centers about the provision of an improved acoustic tile designed for high efllciency absorption of sound over a wide range or over the spectrum of audible sound frequencies.

Acoustic wall structures have been made in various forms, and commonly as pads, slabs and blocks of a porous material such as felt, mineral wool, wood fibre, porous gypsum or other vegetable or mineral fibres. Some of these products rely solely on the porosity of the material, while others additionally provide holes in the material in an effort to improve the sound absorption. The sound absorption is due to the porous nature of the material and to the heat consumed by friction generated in the interior by sound waves traversing the fibrous mass.

In such acoustic wall structures it is found that the sound absorption efficiency is substantially greater for higher audible frequencies than for the low frequencies. In my copencling application, Serial No. 402,793, filed July 17, 1941, for a Vibratable board for acoustic treatment, I disclose an acoustic tile or board designed for absorbing sound frequencies both over the higher and lower ranges, the board or tile, constructed for the usual absorption of high frequencies, being designed so as to provide a vibratable center or diaphragm portion which acts to enhance the, dampening or absorption efficiency of the board or tile for low frequency sound.

The prime object of my present invention pertains to the provision of an acoustic tile made of a sound absorbing, material embodying a structure which provides an increased area and a broken exposed surface for improved high frequency sound absorption and a vibratable body portion for improved low frequency sound absorption. The structure is, therefore, designed for high efficiency sound absorption over the spectrum of audible sound frequencies.

A further object of the invention relates to the provision of an acoustic tile in which the mecham'cal design pennits of predetermlning or controlling the range of absorbable sound frequencies, to meet different acoustic problems'that. present themselves in service. The tiles of the invention may be made with one or more predetermined natural vibration frequencies, and the same or different frequency tiles may be applied to a wall or ceiling, uniformly or in appropriately staggered arrangement, to meet or solve "1e 2 acoustic problem raised in any particular installation.

A still further object of the invention relates to the provision of an acoustic tile of the nature referred .to, the structure of which is attractive and in fact highly ornamental in appearance.

To the accomplishment of the foregoing and such other objects as will hereinafter appear, my invention consists in the acoustic tile features and their relation one to the other as hereinafter are more particularly described in the specification' and sought to be defined in the claims The specification is accompanied by drawings, in which:

Fig. l is a plan view of the improved acoustic tile of my present invention;

Fig. 2 is a view thereof taken in cross-section in the plane of the line 2---2 of Fig. l;

Fig. 3 is a view showing a number of sue acoustic tiles applied to a wall structure;

Fig. 4 is a view of the latter taken in crosssection in the plane of the line 4--4 of Fig. 3;

Fig. 5 is a plan view of a slab or board showing one manner in which the sections of an acoustic tile of th present invention may be cut out or excised from a slab or board;

Fig. 6 is a view of Fig. 5 taken in cross-section in the plane of the line 6-5 of Fig. 5;

Fig. 7 is an exploded view taken in cross-section and showing the manner of rearranging the cutout parts of Figs. 5 or 6 in the step of assemblin the same to form an acoustic tile of the present invention; 1

Fig. 8 is another plan view of the assembled acoustic tile, showing, however, a modification thereof;

Fig. 9 is a view of Fig. 8 taken in cross-section in the plane of the line 9--9 of Fig. 8;

Fig. 10 is a. cross-sectional view corresponding to the view shown in Fig. 6 but showing a modification thereof;

i 11 is an assembled view of an acoustic tile made from the partsor sections of the tile slab or board shown in Fig. 10;

Fig. 12 is a perspective fragmentary view of a part of the base piece or section of the tile showing certain features of construction;

Fig. 13-is a cross-sectional view of another modification showing a different method of as sembling the sections of the tile; and

Fig 14 is a cross-sectional view of a still further modification.

Referring now morein' detail to the drawings and having reference first to Figs. 1 and 2therethe aqq lfitiu tile of the present invention comprises a tile unit generally designated as T made of a suitable sound absorbing material and consisting of a plurality of tile sections such as the sections or pieces a, b, c, d and e of progressively decreasing size, arranged in stepped relation as clearly depicted in these figures. The tile sections or pieces may be formed in any desired way and made of a porous material such as felt, mineral wool, wood fibre, porous gypsum or other vegetable or mineral fibres suitably processed and compacted to produce a light-weight porous sound deadening or absorbing product. The tile unit 'I' may be molded in one piece if desired, to produce the configuration such as shown, for example, in Figs. 1 and 2 of the drawings, and in the preferred construction as will appear here-- inafter, the tile sections or pieces are cut oriabri cated from slabs or boards of the porous material and thereafter assembled to produce the unit as typically shown in Figs. 1 and 2 of the drawings.

One of the objects of the present invention per tains to the provision of an acoustic tile made of a sound absorbing material and embodying a structure which provides an increased area and a broken exposed surface for improved sound absorption and particularly for improved sound absorption of the higher sound frequencies. This is accomplished by having the tile sections of the tile unit, whether made integrally or in assembled separate pieces, built up with the sections of progressively decreasing size arranged in stepped relation, as shown, for example, in l and 2 of the drawings, to form a generally pyramidal type unit.

The other main object of the present invention pertains to the provision of an acoustic tile in which there is provided a vibratable body portion for improved low frequencies sound absorp-- tion, the vibratable body portion acting in enhance the dampening or absorption efilciency of the tile for low frequency sound. This is accomplished by so designing the sections or pieces a to e of the tile unit as to provide a central. body portion which is vibratable as desired. Generlcally this tile unit consists of the base section or piece a formed as an annulus, the top or apex piece e formed as a plaque, and one or more intermediate pieces b, c and d, each also formed as an annular member, interconnecting in stepped relation the apex piece 6 and the base piece a. The annular pieces a to d and the plaque piece 2 may be made in any suitable contour such as round, triangular, square or other shape, the square shape being illustrated in the drawings. When made of separate pieces assembled to form the pyramidal unit, the contiguous contactin faces such as 10, H, I! and H (see Fig. 2) of the pieces are joined together as by means of a suitable adhesive.

By means of this construction, the following results are achieved:

(a) The surface of the acoustic tile exposed to the sound waves is considerably increased. For each the section or piece such surface now comprises a front exposed face or wall and side faces or walls. Thus, for the plaque piece c the exposed surface consists of the front surface s and the side wall surface-s s, s. The same is true for each of the other pieces or sections of the tile and such parts are designated by similar reference characters. When the tile is made by cutting out the sections thereof from slabs or boards of a sound absorbing material, the more porous body oithe tile material becomes exposed. 1. 11

, is indicated in Fig. 1 of the drawings wherein it is shown that the cut or excised surfaces 5' are more porous than the finished surface s of the tile board. When so made, not only is there an increasein the'total area of absorbing material, but a great portion of the thus exposed area being more porous is more highly absorbent of the sound.

(b) The angularly broken surfaces s, s, s, etc., presented by the stepped tile pieces also acoustically cause the breaking up and dispersion of the sound waves incident upon the tile.

(0) The base supported pieces or sections b, c, it and e (or a part of these if a less number of these pieces is used) present vibratable diaphragm for the sound absorption of the lower frequencies. A very important feature of this part of the construction is the air space generally designated as i i (Fig. 2) clcsignodly formed in the region between. the tile sections and the supporting wall or ceiling therefor, which air space allows each tilc to act more cihciently as a diaphragm with consequent dampening of any sound waves striking the same.

A number of tile units of the type shown in Figs. 1 and 2 may be assembled. to i'orrn a ceiling or side wall structure after the manner shown in Figs. 3 and 4 of the drawings. The base section a oi" each of these tile units T may be suitably chamlered on two sides as at l5 and grooved at its other two sides as at 18, as best shown in Figs, 2 and 12 of the drawings, so that the units may be mated as best shown in Fig. i of the drawings, and these tile units may be attached to furring strips ll, IT or any other suitable part of a wall or ceiling as by mailing the base pieces a, a oi the units thereto, as best indicated in Fig. 4 of the drawings. There results an acoustical tile assembly as shown in Figs. 3 and 4 of the drawings, which, in addition to functioning; as above described, presents a very attractive and highly ornamental wall or. ceiling appearance.

The tile unit T in bein cut or excised from a slab or board of fibrous material so as to produce the highly absorbent exposed faces 3, 3', may be cut out substantially without waste from the slabs or boards (from either one board or I from a number of boards) Une way of doing this (ill is depicted in Figs. 5 and 6 of the drawings. A slab or board of the fibrous material generally designated as i8 is saw cut along "the closed lines ll, 2i), 21 and 22 and at an inclination as shown in Fig. 6 or the drawings, to produce the pieces a, b, c, d and c, as clearly shown in these figures.

These excised pieces a to c are then rearranged inversely with respect to their original positions as shown in the exploded view of Fig. 7, and the contiguous or contacting faces thereof are then joined together by suitable cementing material to produce the pyramided assembly shown in Fig. 2 of the drawings. In this way, the tile unit of Fig. 2 may be produced, accomplishing all of the results of the latter, and may be made from a single slab or board of the porous material substantially without any waste.

These tile units may be also constructed to carry out certain features of my invention as described in my aforesaid copending application Serial No. 402,793, flied July 17, 1941, so as to predetermine the vibration frequency of the diaphragm part of the tile unit. This is shown in the modification of the structure illustrated in Figs. 8 and 9 or the drawings. This structure, otherwise the same as that shown in Figs. 1 and 2 of the drawings and designated by similar refer- &

5 ence characters, exponented, however, with the numeral 2, has one of its pieces or sections and preferably the section b slitted bodily as at 23, 24, 25 and 26, leaving 29 and 30 (see Fig. 8). Because of these body slits, thev diaphragm portion of the unit now mainly consisting of the sections e'-, d, c and a part of b may vibrate more readily relative to the remainder of the section b and the base a, the vibration being at the bridge portions 21, 28, 29 and 30. This vibration particularly under the impact of 'low frequency sound waves serves to dampen and absorb the sound waves as above described. The size of the tile unit, the length of the slits, the area or volume of the bridging portions, as well as the weight of the sound absorption material used, are all controllin factors to predetermine the resonance frequency of the tile unit. By applying this improvement, the different. tiles of the invention may be made with one or more predetermined natural vibration frequencies; and the same or different frequency tiles may be applied to a wall or ceiling, uniformly or in appropriately staggered arrangement, to meet or solve the acoustic problem raised in any particular installation. I

A modification of the method and arrangement shown in Figs. 5 to 7 of the drawings is depicted in Figs. 10 and 11 of the drawings. In this modification the sections or pieces a b d and e also cut or excised from a single slab or board of the sound absorbing material and produced substantially without any waste are so cut or excised that instead of rearranging the pieces in inverse relation, these pieces may be moved out in telescopic relation to produce the finished assembly as depicted in-Fig. ll of the drawings. This is accomplished by making the saw-cuts is 20', M and 22'. relatively wide as indicated in Fig. 10 of the drawings, wide enough to permit the parts to be moved into telescopic condition shown in Fig. 11, the saw-cut being dimensioned, however, to permit the side faces of contiguous pieces to engage or meet and be united to form an integral assembly, all as clearly depicted in Fig. 11 of the drawings.

The tile unit may be made from a number of slabs or boards also without any substantial waste of material, and the tile pieces of different boards may be assembled to produce a, tile unit such as shown, for example, in Fig. 13 or Fig. 14 of the drawings. In Fig. 18, the tile unit is made up of the excised pieces a b 0*, d and e selected from a; number of different boards or slabs. In Fig. 14, the tile unit is made up of the tile sections or pieces a b 0 d and a selected from two slabs or boards; thus, the sections or pieces a c and e may be cut from one slab, while the sections 12 and d may be cut from .a second slab. The tile units of Figs. 13 and 14 enable the obtaining of different areas of exposed surfaces and also different areas of engagement between the pieces, both of which factors may be used as an additional control of the ultimate sound absorption characteristics (broken angular faces, extent of exposed surface and natural vibration frequency) of the tile unit.

The manner of making the tile unit of my present invention, the functioning thereof, and the many advantages to be obtained thereby will, in the main, be fully apparent from the above detailed description thereof. By means of the tile of the present-invention, there is produced an increase in the total area of absonbing ma terial which also includes the exposing of'those bridging portions 21, 28,

6 portions most highly absorbent of the sound. Assuming that a commercial acoustic tile is made of /2" thick pulp or fibre board, is 12" square, exposing 144 sq. in. to the sound waves, and has a sound'absorption efliciency of the same tile-fabricatedin accord with my invention would have, say, five steps to a pyramidal shape, would be 2%" thick and show an increased highly absorbing area of over 70 sq. in. If this '70 sq. in. area'was not more absorbent than the surface of the material it would increase the efficiency of the tile about 15%-20%. This compares favorablywith the commercial perforated acoustic tile which is the material here mentioned with 464 perforations per sq. ft., the holes being in diameter and deep, and has a sound absorption of about However, in comparison to the perforated fiat tile my tile possesses additional sound absorbing efficiency due to the broken surfaces and is many more times emcient inthe absorption of the low frequency sound waves due to the'diaphragm eifect. As actually measured, this low frequency absorption can be raised from a 20% efficiency of the flat effected by placing angularly shaped blocks at I tile at 256 cycles to efficiency by the diahragm-impedance obtained. As each individual tile provided with this diaphragm effect will have a peak efiiciency in absorbing certain low frequency sound waves, the spectrum of low frequency absorption can be broadened by using a series of tiles, say, four or more placed adjacent to one another, each so fabricated as to respond to a predetermined sound frequency.

While I have described my invention in some of its more preferred forms, it will be understood that many changes may be made in the structure thereof without departing from the spirit of the invention as defined in the following claims. For example, the tiles may be made in other than rectangular contours. The tile sections may considerably vary in number. The natural vibration frequency may be varie or predetermined by any of the means disclosed or by a suitable combinative selection of such means; also, other means for determining the resonance frequency may be used; for example,

such resonance frequency may be predetermined by spacing some of the tile sections from the others by means of blocks positioned at the four comers. This separation may be preferably the four corners to separate the base section of the tile from the superposed sections, such spacing blocks allowing the determining of the resonance frequency for each tile. Many other modifications may be made. v

I claim:

1. An acoustic tile for walls and ceilings, said tile comprising a plurality of annular frames and a plaque all made of thick porous light-weight sound-absorbing board laid face to face, said frames progressively decreasing in size and being arranged in stepped relation, the largest frame forming the base of the tile and being attachable to a wall or the like, and the plaque being smallest and vibratable and forming the apex of the tile, the exposed face of the tile thereby presenting an angularly broken and increased surface area for high frequency sound absorption, and the central body of the tile being vibratable for low frequency sound absorption.

2. An acoustic tile for walls and ceilings, said tile comprising a plurality of annular frames and a plaque all made of thick porous light-weight 7 sound-absorbing board laid face to face, said frames progressively decreasing in size and being arranged in stepped relation, the largest frame forming the base of the tile and being attachable to a wall or the like, the plaque forming the apex of the tile, and there being at least one frame intermediate the base and the plaque, the exposed face of the tile thereby presenting an anguiarly broken and increased surface area for sound absorption of the higher frequencies, and the base supported pieces being vibratable for sound absorption of the lower frequencies.

3. An acoustic tile according to claim 2, in which one of the base supported pieces is bodily slitted except for bridging regions to predetermine the vibration frequency of the diaphragm part of the tile.

4. An acoustic tile according to claim 1 in which the overlapping portions of the sections are cemented to form the built-up tile.

5. An acoustic tile according to claim 2 in which the sections are cemented at overlapping contiguous faces to form a pyramided tile unit.

6. An acoustic tile for walls and ceilings, said tile comprising a plurality of annular frames and a plaque all made of thick porous light-weight sound-absorbing board laid face to face, said board being more porous interiorly than at its face walls, said frames progressively decreasing in size and being arranged in stepped relation, the largest frame forming the attachable base of the tile, and the plaque being smallest and vibratile and forming the apex of the tile, said frames and plaque being cut, at their side edges to expose the more porous inside body of the tile material, the exposed surface of the tile thereby presenting an angularly broken and increased area for high frequency sound absorption, and the central body of the tile being vibratile for low frequency sound absorption.

\ largest frame forming the attachable base of the tile, the plaque forming the apex of the tile, and there being at least one frame intermediate the base and the apex, the said pieces being cut at their side edges to expose the more porous inside body of the tile material, and the base supported pieces being vibratile for sound absorption of the lower frequencies.

8. An acoustic tile for walls and ceilings, said tile comprising a plurality of annular frames and a plaque all made of thick porous light-weight sound-absorbing board laid face to face, said frames progressively decreasing in size and being arranged in stepped relation to form a pyramidal unit, the outermost frame forming the attachable base of the tile, the plaque forming the apex of the tile, there being at least one other frame intermediate the base and the apex.

9. The acoustic tile of claim 8, in which one of the base supported pieces is bodily slitted except' at bridging regions thereof.

10. An acoustic tile as defined in claim 6, in which the frames and theplaque have their edges cut at an acute angle to one face, the small face of one section having an outside dimension corresponding to the inside dimension of the large face of the next section, said frames being united. with the large face of each section overlapping and cemented to the small face of the next section.

ALBERT B. HURLEY.

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