EP1182641B1 - Soundboard made with fibre composite - Google Patents

Abstract

Resonance plate comprises a core plate (1) and a fiber coating (2) made of long fibers and arranged on both outer sides of the core plate. The core plate has a recess (3) surrounded by the material regions of the core plate where the total volume of the recess is not more than 80%, preferably 20-45%, of the total volume of the core plate. Preferred Features: Single regions of the core plate have different thicknesses.

Description

The invention relates to a resonance panel in fiber composite construction, containing at least one of long fibers and carrier material existing fiber coating, for use for an acoustic Musical instrument, in particular a stringed instrument.

The invention is described below using the example of the resonance plates of Stringed instruments described in more detail. But she is also for others, with a resonant body or soundboard acoustic musical instruments (such as guitars and pianos) are advantageous usable.

The resonant corpus of a stringed instrument becomes of the two Soundboard (ceiling and floor) and the frames connecting them educated. The ceiling is made of spruce wood in the traditional way, the ground is mostly made of maple wood.

In recent times, one has already tried the resonance plates manufacture acoustic musical instruments in fiber composite construction. Structures in fiber composite construction usually consist of long fibers, which are preferably oriented in certain directions, and one Carrier or matrix material, which is generally a duroplastic or thermoplastic.

The previous efforts to produce for acoustic Musical instruments certain resonance panels in fiber composite construction consistently aim to improve the acoustic properties of the as far as possible to replace the substituting wood. Examples of these Experiments in the previously known state of the art give about the DE 37 38,459 A1, EP 0 433 430 B1, US Pat. No. 5,895,872 and US Pat. No. 5,905,219. So DE 37 38 459 A1 "seeks a macroscopic approach that is almost identical to that of wood Heterogeneity "and calls as the goal that" the composite material similar properties as the spruce should have.

Documents JP09244625 and US 4,348,933 Publish piano instruments whose soundboard is off Composite material exist. Document US 4,429,608 Issues a guitar with a resonator plate Composite material.

Unsatisfactory appears on these previously known resonant plates in fiber composite construction, that they are very acoustically good, in traditional construction manufactured solid wood resonance panels at most equivalent, but by no means are superior.

The invention is therefore the object of a resonance plate to create in fiber composite construction, compared to excellent, in traditional construction manufactured solid wood resonance panels a significantly improved acoustic quality has. The resonance plate according to the invention is intended in particular Maintaining the familiar and desired timbre of a Solid wood resonance panel a much higher sound power exhibit.

a) wenigstens ein aus der Resonanzplatte geschnittener Teststreifen weist einen Qualitätsquotienten Q_M = c_L/rho von mindestens 0,02 m⁴/sg, vorzugsweise von mindestens 0,04 m⁴/sg auf, wobei c_L die Schallgeschwindigkeit in m/s der Longitudinalwellen in Längsrichtung des Teststreifens und rho die mittlere Gesamtdichte in g/m3 des Teststreifens ist;

b) der vom Umriß der Resonanzplatte umgrenzte Flächeninhalt der Resonanzplatte ist so groß gewählt, daß

b1) im Falle eines Streichinstruments, die Frequenz der Hauptkorpusresonanz (B1-Mode) in folgenden Bereichen liegt:

• bei der Violine zwischen 480 und 580 Hz, vorzugsweise zwischen 510 und 550 Hz,
• bei der Viola zwischen 380 und 500 Hz, vorzugsweise zwischen 420 und 460 Hz,
• beim Violoncello zwischen 150 und 210 Hz, vorzugsweise zwischen 170 und 190 Hz,
• beim Kontrabass zwischen 80 und 120 Hz, vorzugsweise zwischen 90 und 110Hz,

b2) im Falle einer Gitarre die Frequenz der zweittiefsten Korpusresonanz (0,0-Mode) zwischen 180 und 240 Hz, vorzugsweise zwischen 190 und 220 Hz, liegt,

b3) die Frequenz der tiefsten Resonanz (0,0-Mode) im Falle eines klaviers bzw. konzertflügels des Resonanzbodens zwischen 40 und 60 Hz, vorzugsweise zwischen 45 und 55 Hz, liegt.

This object is achieved according to the invention by the combination of the following features:

a) at least one test strip cut from the resonance plate has a quality quotient Q _M = c _L / rho of at least 0.02 m ⁴ / sg, preferably of at least 0.04 m ⁴ / sg, where c _{L is} the speed of sound in m / s the longitudinal waves in the longitudinal direction of the test strip and rho the average total density in g / m3 of the test strip;

b) the bounded by the outline of the resonance plate surface area of the resonance plate is chosen so large that

b1) in the case of a stringed instrument, the frequency of the main body resonance (B1-mode) lies in the following ranges:

• in the violin between 480 and 580 Hz, preferably between 510 and 550 Hz,
• in the viola between 380 and 500 Hz, preferably between 420 and 460 Hz,
• in the cello between 150 and 210 Hz, preferably between 170 and 190 Hz,
• in the double bass between 80 and 120 Hz, preferably between 90 and 110Hz,

b2) in the case of a guitar, the frequency of the second lowest body resonance (0,0-mode) is between 180 and 240 Hz, preferably between 190 and 220 Hz,

b3) the frequency of the lowest resonance (0,0-mode) in the case of a piano or concert grand piano of the soundboard is between 40 and 60 Hz, preferably between 45 and 55 Hz.

More specifically, the invention is based on the following considerations and To attempt:

If one cuts a test strip from a resonance plate (as will be explained in detail in the description of an embodiment), then the acoustic quality of this test strip can be assessed on the basis of a quality quotient Q _M , which is defined as follows: Q M = C L / rho

Here, C _{L is} the sound velocity (in m / s) of the longitudinal waves in the longitudinal direction of the test strip and rho the average total density (in g / m ³ ) of the test strip.

The quality quotient Q _M is therefore the higher, the greater the speed of sound of the longitudinal waves in relation to the oscillating mass. A large value of Q _M thus corresponds to a favorable mass-stiffness ratio of the resonance plate.

For spruce wood, C _L = 5800 m / s and rho = 400 kg / m ^{3 give} a typical quality quotient Q _M = 0.0145 m ⁴ / sg. As the highest value attainable in spruce sound wood, Q _M = 0.016 m ⁴ / sg was measured in the experiments on which the invention is based. This value corresponds to the values found in resonant plates of the most famous violin makers (such as Antonio Stradivari). Below average spruce soundwood is Q _M = 0.012 m ⁴ / sg.

By contrast, in the case of test strips made of resonance boards in fiber composite construction, quality quotients Q _M of more than 0.06 m ⁴ / sg can be established. The acoustic material quality of fiberglass panels is thus almost four times higher than the acoustic material quality of the best and long-aged spruce soundwood. Despite this well-known fact, however, it has not been possible to create resonance panels in fiber composite construction, which are superior to all solid wood resonance panels, including all necessary aspects. The reasons for this difficulty and the meaning of the combination of features according to the invention will be apparent from the following considerations.

If one manufactures a resonant plate with constant geometric dimensions instead of wood in fiber composite construction, the result is much higher natural frequencies (resonance frequencies) due to the much higher quality quotient Q _M. This increase in the natural frequencies leads to an undesirably sharp or nasal sound and thus changes the timbres of the instrument quite adversely.

One could now think of lowering the high natural frequencies of a resonant plate in fiber composite construction thereby (and to move back towards the natural frequencies of a conventional solid wood resonance panel) that the resonant plate is dimensioned in fiber composite construction thinner than a corresponding solid wood resonance panel , In the experiments underlying the invention, however, it was found that the quality quotient Q _{M of} a resonance panel in fiber composite construction - in contrast to the quality quotient of a conventional solid wood resonance panel - thickness-dependent, namely a reduction in the plate thickness at the same time a reduction of the quality quotient Q _M entails. If, therefore, the thickness of a resonance panel in fiber composite construction is reduced (in order to lower the resonance frequencies back into the desired range), then the quality quotient Q _{M is} also reduced, thus losing the acoustic advantage that the fiber composite construction itself has over the traditional wood Construction method.

Based on these considerations, the invention therefore proceeds a fundamentally different way to tune the resonant frequencies of a Fiber composite construction produced resonant plate in the desired and of solid wood resonance panels usual area lay.

In the solution according to the invention, the natural frequency increase caused by the fiber composite construction (with which the very desired increase of the quality quotient Q _{M is} connected) is compensated by such a geometry-related natural frequency reduction, by which the quality quotient Q _{M is} not appreciably reduced. According to the invention, the surface area of the resonance plate is dimensioned larger than for a soundboard made of solid wood of a string instrument of the same tone for this purpose. An area enlargement of the resonance plate results in a shift of the natural frequencies downwards. Due to its larger area, the resonant plate can then be given a correspondingly greater thickness without the natural frequencies leaving the range required for the desired and familiar timbre. The resulting quality quotient Q _M is therefore significantly higher than that of a non-enlarged, thinner plate in fiber composite construction.

Since an enlargement of the vibrating surface at the same time a Increasing the sound radiation and thus increasing the acoustic efficiency of the instrument results in The solution according to the invention not only the desired timbre of realizes classic string instruments, but it will be about it In addition, the other, resulting from the sound radiation sonic properties, such as "carrying capacity", "volume" and "Dynamics", improved. The resonance plate according to the invention allows it's about building instruments that respect the listening habits (Klangfarbenempfinden) the conventional, made of solid wood Instruments, but with regard to their acoustic characteristics Efficiency far superior to traditional instruments are.

Would you be in a made of solid wood resonant body of a conventional string instrument the area of the Magnify resonant plates, so this would be the natural frequencies of the Move the instrument down so much that it becomes dull ("pot-shaped") tone results. In a conventional stringed instrument With solid wood panels would be a plate broadening due to the low transverse stiffness of the Solid wood panels also for the formation of vibration modes with narrow, parallel lying, antiphase antinodes lead, the due to hydrodynamic short circuits a small Sound radiation result (see Cremer, Lothar: "Physics of Violin ", Stuttgart 1981, p.341).

An area enlargement of the resonance plate is only then makes sense acoustically when a material (such as a Fiber composite material) with a higher compared to wood Bending stiffness and consequently a higher speed of sound is used.

The formulated in the feature b) of claim 1 acoustic condition serves to control comparable timbres. It is about in feature b1) by the frequency of the main body resonance, the - According to the relevant literature - designated B1-mode becomes. In feature b2) is the second deepest for the guitar Called body resonance, which is referred to as 0.0-mode. feature b3) concerns the lowest resonance of the sound board of pianos or concert grand pianos, which according to their vibration also with 0,0-mode is called.

The resonances mentioned, in particular their respective typical Vibration, become even closer in the embodiments explained.

In the experiments underlying the invention were in Acoustic laboratory of the inventor Modalanalysen of outstanding Instruments of famous violin makers (such as Antonio Stradivari or Guarneri del Gesu). For violins whose timbres of Artists and trained listeners as pleasant and balanced be judged, the B1 mode is always in a relatively narrow Frequency band between 510 and 550 Hz. A violin with a B1 mode clearly above this frequency range tends to sound rough and sharp, while a violin with a B1 mode below this Frequency range tends to be dull and potty has. The natural frequency of the B1 mode can therefore be used as a reliable acoustic indicator for the timbre of a String instrument are considered.

Advantageous embodiments of the invention will become apparent from the Dependent claims.

These and other details of the invention (such as the extraction, Measurement and evaluation of test strips) are described below explained in detail the drawing.

Figs. 1 to 4 show the typical natural vibration mode of the main body resonance (B1 mode) as it is given in violins, violas, cellos and double basses. Parts of the literature call the B1-Mode also C3-Mode (Jansson) or B1 ₊ Mode (Hutchins). The mode is determined by means of experimental modal analysis by measurement. In experimental modal analysis, a variety of transfer functions (acceleration divided by force, or vibration response divided by vibration excitation) are measured by exciting the instrument at a variety of co-ordinate coordinates using impulse hammers (eg PCB 086C80). The vibration response is measured by means of an accelerometer (eg PCB 352B22) at the so-called driving point. As a driving point, the upper end of the side edge (bass bar side) of the bridge is selected. All of these measurements take place in the ready-to-play state of the instrument, with only the strings being damped by means of foam in such a way that the sharp-edged string resonances are damped, while the body resonances of the instrument to be determined are not changed. Apart from the piano or grand piano, which are measured in normal standing position, the measurement of the other musical instruments, in which the resonance plate according to the invention is installed, with free-free storage. Appropriately, the instruments are stored soft on foam pad in the area of the upper and lower block. The transfer functions are evaluated by means of the relevant programs (eg STAR Structure) in the manner customary for modal analysis.

• in Längsrichtung des Bodens 2 verlaufen zwei Knotenlinien 3a und 3b, wobei die linke Knotenlinie 3a durch den Bereich des Stimmstocks 5 verläuft. Der Mittelbereich des Bodens 2 schwingt somit gegenphasig zu seinen beiden seitlichen Rändern. Für die B1-Mode ist diese Querbiegeschwingung des Bodens charakteristisch. Bei einigen wenigen Instrumenten kann beobachtet werden, daß die beiden Knotenlinien 3a und 3b sich im oberen Bereich des Bodens 2 bogenartig zusammenschließen.
• die (weiß gezeichnete) untere rechte Backe 4 der Decke 1 schwingt gegenphasig zu dem den größten Anteil der Deckenfläche einnehmenden (schwarz gezeichneten) Schwingungsbauch im Bereich des Baßbalkens 6, wobei die Knotenlinie 3c, welche diese gegenphasigen Schwingungsbäuche trennt, in der Regel durch den unmittelbaren Nahbereich des Stimmstocks 5, und anschließend durch das rechte (mit "f" bezeichnete) f-Loch verläuft, um den Deckenumriß im Bereich der größten Umrißbreite unten rechts zu verlassen.

In Fig. 1, the B1 mode of a violin is represented by Contourplot, the left resonance plate, the ceiling 1 and the right resonance plate the bottom 2 - each in the view from the outside - represents. Thus, although the measurement takes place in the assembled, ready-to-play state of the instrument, the corpus is displayed "unfolded". The black areas indicated by "+" oscillate out of phase with the white ones marked "-", with the black areas of the ceiling swinging inwards simultaneously with the black areas of the floor towards the outside of the body and half after a period of oscillation , The same applies to the white areas of both plates. This phase relationship is shown in FIG. 2 by means of greatly exaggerated amplitudes (bold lines); It shows a cross section through the body at the designated in Fig. 1 with A line. For orientation, the thin lines reflect the resting state of the body. The details of the amplitude distribution may vary from instrument to instrument; typical of the natural mode of the B1 mode, however, are always the following features:

• in the longitudinal direction of the bottom 2 extend two node lines 3a and 3b, wherein the left node line 3a extends through the region of the voice block 5. The central region of the bottom 2 thus oscillates in antiphase to its two lateral edges. For the B1 mode this transverse bending vibration of the soil is characteristic. In the case of a few instruments, it can be observed that the two nodal lines 3a and 3b join together arch-like in the upper region of the bottom 2.
• the (white drawn) lower right cheek 4 of the ceiling 1 oscillates in opposite phase to the largest portion of the ceiling surface occupying (black drawn) antinode in the area of the bass bar 6, the nodal line 3c, which separates these antiphase antinodes, usually by the immediate Close range of the voice post 5, and then through the right (marked "f") f-hole to leave the ceiling outline in the area of the largest outline width at the bottom right.

Fig. 3 (ceiling) and Fig. 4 (bottom) show for better understanding also the natural mode of the B1-mode, but now (im Contrary to Contourplot Fig. 1) as a wire grid model, wherein FIG. 3a and 4a deflected by -90 °, Fig. 3c and Fig. 4c with the + 90 ° deflected state relative to that in Fig. 3b and Fig. 4b shown rest state with 0 °.

The frequency responses shown in FIGS. 5 to 8 represent the typical Entrance accelain dance of a violin (FIG. 5), a viola (FIG. 6), a cello (Fig. 7), and a double bass (Fig. 8). The input acellance is that transfer function in which the vibration excitation and the vibration response at the same Measuring point to be measured. As a measuring point is the above driving Point chosen. The X-axis of the input acellance is around the frequency, with the Y-axis around the vibration level (Acceleration divided by stimulating force) in dB. The different resonances are clearly as single peaks too detect. In the violin and the viola (Fig. 5 and 6) forms the B1 mode typically the last outstanding resonance peak a body resonance area formed by the envelope 7. This resonance area is always by a steep burglary. 8 (Antiresonance) from the higher frequency plate resonance peaks separated. As can be seen in FIG. 7, the B1 mode forms at Violoncello usually the highest low-frequency resonance peak Below 300 Hz. The B1 mode is often without cello physical measurement methods by the so-called Wolfston susceptibility that of the canceled tone (especially on the C-string) whose fundamental frequency is the resonance frequency of the B1 mode equivalent.

In the double bass (Figure 8) the B1 mode is usually second, the Helmholtz resonance Ao following main body resonance in the area around 100 Hz. The resonance peaks of the Helmholtz resonance Ao and the lying below the B1 mode T1 mode are in Fig. 4 to 7 as such marked.

The second deepest mentioned in feature b2) of claim 1 Body resonance of the acoustic guitar is shown in FIG. 9 illustrated. This resonance is in the literature [see Fletcher N. H. and Rossing T.D .: The Physics of Musical Instruments, New York 1991] is described as a mode with 0,0-character, as they neither in longitudinal in the transverse direction of the ceiling 9 node lines, but rather, by a single antinode on each resonance plate (Ceiling and floor) is marked. The connection of cavity, Ceiling and floor leads to three body resonances in the guitar 0,0 characteristic, namely for Helmholtz resonance and two frequency closely adjacent, about 100 Hz above the Helmholtz resonance lying body resonances. When in feature b2) This mode is the lower frequency of these two the latter resonances, and thus, since the Helmholtz resonance the The first body mode of the guitar is the second deepest Corpus resonance, or the middle of the three body resonances with 0,0-character. It is different from the higher frequency, third Body resonance with 0,0 character due to the phase position between the ceiling and soil. Ceiling and floor swing at the feature b2) called resonance in phase (in the same spatial direction), so that the body bends like a thick plate as a whole; in the On the other hand, higher-frequency, third 0-0-body modes swing blanket and Ground in phase, so lead a "breathing" movement of the body out. The mode of vibration of the mode mentioned in feature b2) is in Fig. 9 illustrated by lines of equal amplitudes 10. These are centered around the area of the web 12 and describe one Antinode, which is about the shape of the lower contour of the Resonant plate occupies [cf. Richardson, B.E. "The acoustical development of the guitar "in: Catgut Acoust, Soc., J. Vol. 2, No. 5 (Series II) May 1994; P. 5; Fig. 4b].

Feature b3) is the lowest resonance of the Soundboard of the piano or concert grand piano. This resonance will according to their vibration also with 0,0-mode designated. Their vibration shape is the same by lines Amplitudes 10 are shown in FIG. 10 [cf. Kindel: Modal Analysis and finite element analysis of a piano soundboard "M.S. University of Cincinnati. Quoted from: Fletcher N.H. and Rossing T.D .: "The Physics of Musical Instruments", New York 1998, p. 382].

The measurement of the quality quotient Q _M mentioned in claim 1, feature a) is expediently carried out as follows:

Strip elements 14 are cut out of the surface of the resonance plate. The proportions of a strip element are derived as follows from the average thickness (D _m ) of the strip element: The length L of the strip corresponds to 25 times the thickness D _m , the width B of the strip corresponds to 5 times the thickness D _m .

The sound velocity C _{L of} the longitudinal waves in the longitudinal direction of the strip element (strip) is then determined by measurement. The resonance method established in the field of structure-borne noise measurement is used for this measurement. It is illustrated in FIG. 11:

The strip 14 is in the two node lines (n ₁ and n ₂ ) of its first bending natural frequency elastically mounted on rubber bands or foam wedges 15 (free-free boundary conditions). The strip is excited sinusoidally by airborne sound. For this purpose, a miniature loudspeaker 16 is positioned at a distance of about 5 mm below one of the two strip ends, which is connected to a power amplifier 17. The sinusoidal signal is generated by a sine wave generator 18. The oscillation response of the strip sinusoidally excited in this way is removed by means of a sound level meter 19. For this purpose, the microphone 20 of the sound level meter is positioned at a distance of about 1 mm above the end of the strip opposite the loudspeaker. At the sine wave generator 18, the frequency is gradually increased until the natural frequency of the first bending natural vibration of the strip can be read by the associated level maximum of the level peak at the sound level meter. (The low natural frequency deviation due to the damping can be neglected here). The frequency f _{2, 0} (in Hz) corresponding to the level maximum of this resonance peak is noted. (Meaning of indexing fn _{; m} : number of node lines running in the transverse direction of the strip n = 2; number of longitudinal node lines m = 0; the corresponding natural mode is symbolized by the (dashed) maximum displacement lines 21 in Fig. 11).

The sound velocity (c _L ) of the longitudinal waves (in m / s) is defined as follows: C L = (0.98 * f 2 0 * L 2 ) / D m

Where L is the strip length (in m), D _{m is} the mean strip thickness (in m), and f _{2; 0 is} the resonant frequency (in Hz). (If the strip thickness is not constant according to claim 5, averaged over the different thicknesses and an average strip thickness D _{m is} used.)

The mean total density rho of the strip is calculated from rho = m / V. Where m is the total mass (in g) and V is the total volume (in m ³ ) of the strip. The total volume V is determined by measuring the strip dimensions (strip length L (in m), strip width B (in m), and the average strip thickness D _m (in m)) corresponding to V = L * B * D _m .

FIG. 12 shows the physically essential relationship of the thickness dependence of the quality quotient Q _M on which the invention is based: on the X axis, the strip thickness D _m (in mm), on the Y axis the quality quotient Q _M (in m ⁴ / sg) applied. The curves labeled A (maple) and F (spruce) represent the quality quotient of the wood species conventionally used for gutting panels. It is shown to be thickness independent and to be 0.0155 m ⁴ / sg for this spruce and 0.0067 for maple m ⁴ / sg lag.
The curve denoted by VS shows the quality quotient Q _M for the test strips of the resonance plate according to the invention manufactured as a fiber composite sandwich. The worsening of this quotient Q _{M can} clearly be seen by reducing the strip thicknesses below 4 mm. Depending on the material properties of the core plate and the fiber composite material (fiber basis weight, resin content, etc.) and depending on the core plate recesses and fiber coating (direction and density), different curves VS are obtained, ie different dependencies of the quality quotient Q _M on the plate thickness. According to claim 2, the thickness of the resonant plate is dimensioned so that the quality quotient Q _{M of} at least one test strip cut from the resonance plate has at least 90% of the maximum value achievable with the selected fiber composite material. This 90% line 28 is shown in FIG. 12 for the fiber composite material used there.
The function VS in Fig. 12 immediately reveals that compensation for the natural frequency elevations of the resonant plate by reducing its thickness results in deterioration of the acoustic quality. According to the invention, on the other hand, the sound necessary natural frequency reduction is achieved by increasing the area bounded by the contour of the resonance plate area. FIGS. 13 and 14 show an embodiment for this purpose. Since the width of the resonant plate in the first approximation in the second power in the natural frequencies, even a relatively small broadening of the outline 23 of the invention constructed with fiber composite coating 24 resonance plate by about 5% compared to the conventional outline 22 (dashed lines) accomplish the required frequency shift ,
The core plate 26 of the resonance plate has, as shown in Fig. 14 on a segment, according to claim 4 recesses 27, wherein the total volume of all recesses is at most 80%, preferably between 20 and 45% of the material-filled total volume of the core plate. This feature allows an improvement in the mass-stiffness ratio of the resonator plate. According to claim 5, the segment of the resonance plate shown in Fig. 14 has a different thickness D. According to claim 6, it has a multi-directional fiber coating consisting of non-parallel fibers 25.

Claims (6)

1. Soundboard of composite fibre material construction comprising at least one composite fibre laminate consisting of long fibres and carrier material for use for an acoustic musical instrument, particularly a bowed stringed instrument, characterised by the combination of the following features:

   a) at least one test strip cut out of the soundboard has a quality quotient Q_M = c_L/rho of at least 0.02 m⁴/sg, preferably at least 0.4 m⁴/sg, where c_L is the velocity of sound in m/s of the longitudinal waves in the longitudinal direction of the test strip and rho is the average total density in g/m³ of the test strip;

   b) the area of the soundboard defined by the outline of the soundboard is chosen to be of such a size that

   b1) in case of a bowed stringed instrument the frequency of the main body resonance (B1 mode) lies within the following ranges:

   in the violin between 480 and 580 Hz, preferably between 510 and 550 Hz,

   in the viola between 380 and 500 Hz, preferably between 420 and 460 Hz,

   in the cello between 150 and 210 Hz, preferably between 170 and 190 Hz,

   in the double bass between 80 and 120 Hz, preferably between 90 and 110 Hz,

   b2) in case of a guitar the frequency of the second-lowest body resonance (0,0 mode) lies between 180 and 240 Hz, preferably between 190 and 220 Hz,

   b3) in case of a piano or grand piano the frequency of the lowest resonance (0,0 mode) of the soundboard lies between 40 and 60 Hz, preferably between 45 and 55 Hz.
2. Soundboard as claimed in Claim 1, characterised in that the thickness of the soundboard is such that for the given composite fibre material the quality quotient Q_M of at least one test strip cut out of the soundboard is at least 90% of the maximum value which can be attained with this composite fibre material.
3. Soundboard as claimed in Claim 1, characterised in that it comprises a core plate and at least one outer composite fibre laminate consisting of long fibres and carrier material.
4. Soundboard as claimed in Claim 3, characterised in that the core plate has at least one recess within the area defined by the outline of the soundboard, the total volume of all recesses amounting at most to 80%, preferably between 20 and 45%, of the total volume of the core plate filled with material.
5. Soundboard as claimed in Claim 3, characterised in that individual areas of the core plate have a variable thickness.
6. Soundboard as claimed in Claim 1, characterised in that the composite fibre laminate is single-layer and at the same time multidirectional.

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