JPH03213893A - Lid for musical instrument - Google Patents

Abstract

PURPOSE:To realize a woody sound by providing plural spaces inside in the thickness direction of the lid and increasing the timbre relative material property value E/G of the lid. CONSTITUTION:The lid 1 is formed by connecting plural straight grained timber veneers 2, 2..., a long dowel is fitted at right angles to the grain direction M, and lid rods 10 are fitted to the veneers while intersecting orthogonally with the grain direction. Grooves 5, 5... formed in the veneers 2, 2... in the grain direction M are widest at the center part of the lid 1 and become narrower toward the end parts. The grooves formed in both the joined surfaces of the joined parts of the veneers 2 and 2 are matched with each other to form a hollow part. The strength of the part of the groove to shearing deformation is decreased and the characteristic value of the whole lid 1 corresponding to a coefficient G of lateral elasticity becomes small. Consequently, the timbre relative material property value (E/G) is increased and the warm woody sound is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a soundboard for a musical instrument suitable for use in a piano or the like.

``Prior Art'' As is well known, a piano is a type of percussion instrument, and its sound production mechanism will be explained with reference to FIG. string 62
The free vibration of the string 62 excited by this,
A soundboard 63, which is a sound radiator, is driven through a string support section called a bridge 64, and as a result, sound is radiated from the soundboard 63. As can be seen from the above sounding mechanism, the role of the soundboard 63 in the piano is extremely important, and it is no exaggeration to say that the characteristics of the sound of the piano are largely determined by the physical properties of the material of the soundboard 63. .

There are two characteristics required for a piano sound: good response to string strikes and a moderately extended sound. Therefore, it is necessary for the soundboard 3 to have characteristics that satisfy the above-mentioned requirements, and spruce wood such as spruce has been considered suitable as a material having such characteristics.

By the way, when a soundboard is made of natural wood, the specific elastic modulus E/γ (E Young's modulus, γ: density) is limited by the value unique to the wood, so it is not possible to achieve a certain level of sound efficiency. There was a problem. Therefore, soundboards were developed that increased the efficiency of sound production and produced sounds from low to high ranges (for example,
No. 57894, JP-A-60-57895). In this soundboard, the material of the core material of the soundboard having a laminated structure is selected so as to have a large transverse elastic modulus G and a small shear loss tangent tan δG, or a sheet is interposed in the laminated structure.

In addition, in order to make the tone clearer, carbon fibers arranged in the grain direction of the outer layer were attached along both sides of the inner layer to increase the longitudinal elastic modulus E and decrease the shear loss tangent janδG. A soundboard was also developed (Unexamined Japanese Patent Publication No. 57-1
No. 36693). According to this soundboard, the damping rate due to internal friction is reduced.

``Invention or Problem to be Solved'' However, the conventional soundboards described above are not sufficient to bring out the good woody sound (warmth of non-metallic sound) characteristic of natural instruments, and have inferior audible characteristics. There was a problem.

This invention was made in view of the above-mentioned circumstances, and can fully demonstrate the goodness of woody sound, and can achieve a warmer woody sound overall than when using natural materials. Another object of the present invention is to provide a musical instrument soundboard whose sound quality can be artificially and freely set according to the sound range of each part.

"Means for Solving the Problems" In order to solve the above problems, the present invention provides a soundboard for a wooden musical instrument, which has a plurality of spaces provided inside the board in the thickness direction, and furthermore, the plurality of spaces are are characterized by being different in at least one of the shape or arrangement.

"Operation" According to the above-mentioned configuration, since a plurality of spaces are provided inside the soundboard in the thickness direction, the strength against shear deformation of the inner layer of the soundboard, that is, the property equivalent to the transverse elastic modulus G, decreases. ,
As a result, the timbre-related material physical property E/G, which is the ratio of the longitudinal elastic modulus E and the transverse elastic modulus G of the soundboard, increases, and as a result, the internal friction loss Q-' in the high frequency band when driving the soundboard increases. This creates a warmer woody sound. Furthermore, since at least one element of the shape or arrangement of each space is different, by appropriately changing each of these elements according to the string support part on the bass side to the treble side of the soundboard, the difference between each range can be improved. You can set the sound quality balance to the optimal state.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Basic principle First, the basic principle of this invention will be explained.

First, as mentioned above, what is important about the vibration characteristics of a piano soundboard on the time axis are its good response to string vibrations and its appropriate energy conservation, that is, its appropriate non-damping properties. This is because the former characteristic corresponds to the good rise of the sound, and the latter characteristic corresponds to the extension of the sound. The sinking Young's modulus E/γ (E・dynamic Young's modulus, γ・density) and the internal friction loss tan δ are known as physical quantities for evaluating soundboard materials from these two viewpoints. Spruce subluce, which is excellent as a soundboard material, has a large E/γ and a small tanδ.

Next, in order to consider the sound quality of a piano, it is necessary to consider the frequency characteristics of the soundboard material. Regarding the correlation between the material properties of piano plate materials and their sound quality, an analysis has been attempted from various viewpoints in ``Piano Sound Quality Engineering,'' Journal of the Japan Society of Mechanical Engineers, Vol. 91, No. 836. Here, in particular, the correlation between the frequency characteristics of the soundboard material and the timbre will be explained in detail.

The timbre of a piano can be said to be the temporal change in the frequency characteristics of the sound (spectrum envelope).
In that sense, the frequency characteristics of the soundboard material have a large effect on the piano sound.

Generally, in order to find the frequency characteristics of acoustic materials,
A plate-shaped sample of a certain shape is vibrated under boundary conditions with both ends free, and the resonance frequencies of the flexural vibrations excited thereby and the damping characteristics there are measured.

The apparent Young's modulus and internal friction loss Q-' at each resonance point can be determined from this measurement result and the solution of the Euler-Bernoulli vibration equation, which takes into account only the elasticity of the plate. The frequency characteristics of these apparent material properties are correlated with the unique audible timbre tendency of each acoustic material.

Originally, Young's modulus is a material-specific physical property and should have no frequency dependence, but the fact that the apparent Young's modulus obtained through the above measurements and analysis has frequency characteristics indicates that it describes the vibration behavior of the plate. This can be explained by the so-called Timosoenko beam vibration equation, which also takes into account the shear force (and rotational inertia) generated in the plate, or by Goens' solution obtained under the boundary condition that both ends are free. .

In Goens' solution, the apparent Young's modulus E at each resonance point is
' freq has a frequency characteristic as shown below by considering the shearing force within the system (however, this is an example of a rectangular bar with an equal cross section).

Here, f: rod natural frequency, Q: rod length, h: thickness, m
, F (m) vibration order, constant determined by boundary conditions, S: constant determined by cross-sectional shape.

In this case, from the perspective of the physical properties of the material, the true physical property E of the material may be found by using Goens' solution as a correction formula for the above measurement and analysis results.However, regarding the characteristics of the piano sound on the frequency axis, When discussing this, the apparent Young's modulus is a more important element due to its correspondence with the auditory sense of timbre.

This is because, at the material level, the frequency characteristics of the apparent Young's modulus, which changes depending on the value of the timbre-related material property E/G, are
Determine the frequency characteristics of the periodic strain in the soundboard excited by string vibration, that is, the displacement amplitude, and as a result, determine the frequency characteristics of the energy loss due to internal friction, which gives rise to filter characteristics and changes the timbre. This is because it is thought that the decision will be made.

In general, wood has a higher E/R than other industrial materials.
The value of G is large. Among them, the E/G value of spruce wood such as Subruce is particularly large. The high loss in the high frequency range of materials such as spruce, or in other words, the high-cut filter-like characteristics, are thought to be one of the factors that create the so-called ``wood-like'' sound, that is, the warm tone. .

As mentioned above, based on the results of various sensory tests to date, the timbre-related material physical properties E/G, which are considered to influence the frequency characteristics of vibration energy loss, have been found to affect the following characteristics of the piano sound, even within the range of piano SUBRUCE soundboard materials. It has been revealed that there is a strong correlation with characteristics.

(1) Tone-related material properties E/G have a positive correlation with the reverberation characteristics of sound, that is, the naturalness and depth of the sound.

(11) Tone-related material physical properties E/G have a positive correlation with the depth characteristics of the sound, that is, the depth and the amount of low components.

(iii) Tone-related material properties E/G have a negative correlation with noise characteristics, that is, noise contained in acoustic radiation.

If these characteristics are expressed using timbre expressions, it is as per the memorial service.

As is clear from the above explanation, by increasing the value of the timbre-related material physical property E/G of the entire soundboard and emphasizing its high loss in the high frequency band, in other words, the characteristics as a high-cut filter, the overall This means that the quality of the woody sound as a natural instrument is fully demonstrated, and a warmer woody sound is achieved.

Based on the above consideration, in this invention, the E/
The basic principle is to artificially increase the G and thereby create a warm woody sound.

On the other hand, the aforementioned Japanese Patent Publication No. 60-57894, 60-57
In No. 895, since the transverse elastic modulus G was increased, the value of E/G became small, and a woody sound could not be obtained. Furthermore, in JP-A-57-136693, since the internal friction loss Q -1 in the high range is made small, the high frequency components are acoustically radiated and become noise components, making it impossible to obtain a warm wood sound quality.

(2) Structure and operation of the embodiment [First embodiment] FIG. 1 is a plan view showing the structure of the first embodiment of the present invention. In the figure, the soundboard l consists of a plurality of straight-grained wood veneers 2
．． It is formed by combing 2... The soundboard l in this embodiment is a soundboard for a grand piano. Here, the AA-line cross section and the BB- line cross section in the same figure
Linear cross sections are shown in FIGS. 2 and 3, respectively. The long bridge 3 shown in these figures is provided along the grain direction M at the center of the soundboard l, and short bridges 3 are provided at the ends of the soundboard l, although not shown. The baton lO shown in these figures is made of single plate 2.
2 is attached perpendicularly to the wood grain direction, and serves to compensate for vibration propagation in the direction perpendicular to the wood grain direction and to reinforce the entire soundboard l.

In addition, the part indicated by the broken line in Fig. 1 is the veneer 2.2...
Grooves 5.5 are provided along the grain direction M at the abutting portions. That is, as shown in FIG. 3, a groove 5 is provided along the center of the layer of the veneer 2. The widths of these grooves 5,5, . . . are widest at the center of the soundboard 1, as shown in FIG. 1, and gradually become narrower toward the ends. Here, FIG. 4 is a view taken from arrow C shown in FIG. 1, and FIG. 5 is an enlarged plan view showing the veneer 2. As can be seen from these figures, the veneer 2 is The width of the groove 5 is different on the left and right sides. Also,
As shown in FIG. 2, the grooves 5.5 provided on both joint surfaces of the joint portion of the veneer 2.2 are aligned, and a hollow portion is formed by this pair of grooves.

As mentioned above, when the grooves 5 are provided on the joint surface of the veneer 2, the grooves 5
The strength against shear deformation decreases in the part of the soundboard 1.
The characteristic value corresponding to the overall transverse elastic modulus G becomes smaller. Therefore, the value of E/G increases, and the characteristics shown in Table 1 above are obtained. In this case, the extent to which the E/G can be increased can be arbitrarily set depending on how the depth, width, etc. of the groove 5 are set.

For example, as shown in Fig. 6, if the widths of the grooves at the left and right ends of the veneer 2 are respectively WISW2, the property equivalent to the transverse elastic modulus of the material is multiplied by (W-(W1+w2))/W. be able to. Further, the widths of the grooves at the left end and right end of the veneer 2 adjacent to the veneer are set to W2 and W3, respectively, and Wl<W2<W3 toward the center of the soundboard 1. Note that the reverse setting may be made (Wl>W2>W3).

Here, the frequency characteristics of the internal friction loss Q in this example are shown in FIG. The illustrated curve a is the frequency characteristic in this example. Moreover, the curved line is the frequency characteristic of a normal soundboard material (natural material such as subluce material). As can be seen from this figure, in the characteristics of this example, the amount of loss is large on the high frequency side, and a kind of high-cut filter-like characteristic is obtained. Therefore, a warm woody sound can be obtained. Furthermore, by appropriately varying the groove width, it is possible to set the optimal sound quality required for each range.

In this case, since the Young's modulus and specific gravity of the soundboard 1 hardly change, other acoustic factors that depend on the Young's modulus and specific gravity, such as the pressure Young's modulus E/γ and the acoustic radiation effect E/γ3, The properties are almost never lost.

Note that it is most effective for the groove 5 to be located on the neutral axis of the soundboard l.

Further, in the first embodiment described above, the width of the groove 5 was increased toward the center of the soundboard l, but conversely, the width of the groove at the center was decreased and toward the end. It is also possible to configure the groove width to be increased accordingly. Either one may be selected according to the characteristics of the desired piano sound.

Also, instead of gradually increasing (decreasing) the groove width, it is possible to increase (decrease) only the groove width in a specific part, or
Each groove width may be set according to arbitrary regularity.

[Second Embodiment] FIG. 9 is a plan view showing the configuration of a second embodiment of the present invention. In the figure, a soundboard 1 includes a plurality of straight-grained wood veneers 2
．． It is formed by combing 2... The soundboard 1 in this embodiment is a soundboard for a grand piano. Here, the AA-line cross section and the BB-B cross section in the same figure.
- line cross sections are shown in FIGS. 10 and 11, respectively. The long bridge 3 shown in these figures is provided along the grain direction M at the center of the soundboard l, and short bridges 3 are provided at the ends of the soundboard l, although not shown. The baton lO shown in these figures is attached perpendicular to the wood grain direction to the veneer 2.2, and serves to compensate for vibration propagation in the direction perpendicular to the wood grain direction and to reinforce the entire soundboard l. do.

Further, the portions indicated by broken lines in FIG. 9 are grooves 25, 25, . This groove 25 is the 11th
As shown in the figure, it is provided along the center of the layer of the veneer 2. The width of these grooves 25, 25, . . . gradually increases from one end of the soundboard 1 to the other end, as shown in FIG. Here, FIG. 12 is a view taken from arrow C shown in FIG. 9, and FIG. 13 is an enlarged plan view showing the veneer 2. As can be seen from these figures, the veneer 2 The width of the groove 25 gradually increases linearly (tapered) from one end to the other end. Further, as shown in FIG. 1θ, the grooves 25 and 25 provided on both joint surfaces of the joint portion of the veneer 2.2 are aligned, and a hollow portion is formed by a pair of these grooves.

As described above, when the grooves 25 are provided on the joint surface of the veneer 2, the strength against shear deformation is reduced in the grooves 25, and the characteristic value corresponding to the transverse elastic modulus G of the entire soundboard l is reduced. Therefore, the value of E/G increases, and the characteristics shown in Table 1 above are obtained. In this case, the extent to which the E/G can be increased can be arbitrarily set depending on how the depth and width of the groove 25 are set.

For example, as shown in FIG. 14, if the widths of the grooves at the left end and right end of the veneer 2 are W1 and W2, respectively, then in those parts, the property equivalent to the transverse elastic modulus of the material is (W - (W
1 + w2) ) /W times. In this embodiment, since the width of the groove 25 changes in the direction of the wood grain,
The value of E/G also changes sequentially. Therefore, by setting the change rate of the groove width, the characteristics of the entire soundboard can be set arbitrarily.

Even in such an embodiment, the frequency characteristic of the internal friction loss Q becomes as shown by curve a in FIG. 7, and therefore a warm woody sound can be obtained. Furthermore, depending on the rate of change of the groove width, it is possible to set the optimal sound quality required for each range, and in particular, the sound quality in the low range can be significantly improved.

Note that it is most effective to provide the groove 25 at a neutral position of the soundboard l.

Further, in the second embodiment described above, the groove width changes linearly, but it may be configured to change curved, as shown by the dashed line in FIG. 13.

Furthermore, the groove width may be changed stepwise rather than continuously, and the groove width may be changed only in a specific portion.

[Third Embodiment] FIG. 15 is a plan view showing the overall configuration when the third embodiment of the present invention is applied to a grand piano, and a sectional view taken along the line A-A' of this figure, and B -B' line cross-sectional view, arrow C
Perspective views seen from this direction are shown in FIGS. 16 to 18.

In these figures, the soundboard 35 is made up of a plurality of straight-grained wood veneers 36.36. The longitudinal direction of each straight-grained wood veneer 3636,... coincides with the grain direction M thereof. And each straight grain wood veneer 36, 36. In the inner layer portions of the contact surfaces 36a, 36a, . . . that contact each other, round holes 37, 37, . ... are drilled in each. Each of these round holes 37, 37. ...
is the drilling interval P,,P! +P3+... changes along the grain direction M, and as the position of the string support part of the soundboard 35 becomes higher pitched, the drilling intervals P , , P , , P 3
．． ...is gradually set to become a dog. Here, in FIGS. 16 and 17, a long bridge 40 provided on the upper surface of the soundboard 35 and a bar 4 provided on the lower surface!
However, in FIG. 1, only the long piece 40 is shown by a dashed line, and the illustration of one stick 41 is omitted. The longitudinal direction of the long piece 40 substantially coincides with the wood grain direction M, and the lengthwise direction of the long piece 40 is from one end 40a to the other end 40a.
The strings are arranged in such a way that the pitch becomes higher in sequence toward the string.

Round hole 37.37. To explain the processing method for . . . , first, each straight-grained wood veneer 36, 36. A round hole 37, 3 with a constant diameter and a constant depth is formed in the contact surface 36a of ... along the neutral axis in the thickness direction.
7. . . . at different intervals Pl.

Drill with P*, Ps,... As a result, the round hole 3 extends in a direction substantially perpendicular to the grain direction M of the straight-grained wood veneer 36.
7,37. A row of... is formed. In this way, the round holes 37, 37. ... Straight-grained wood end plate 36 with rows of -
, 36. The sound board 35 is produced by joining the pieces in the width direction and gluing them together as shown in FIG. 20.

In the above configuration, the planar projected area of the entire soundboard 35 is S
Assuming that the cross-sectional area (effective area) of the plane including the neutral axis of the soundboard 35 is S' as shown by diagonal lines in FIG. 21, each round hole 37, 37 . By appropriately setting the diameter and depth of the material, the strength against shear deformation of the material, that is, the property equivalent to the transverse elastic modulus G, can be set to approximately S'/S (<1) times, As a result, the value of the timbre-related material physical property E/G, which is the ratio of the longitudinal elastic modulus E and the transverse elastic modulus G of the soundboard 35, can be increased to a desired value.

In this way, by increasing the value of the tone-related material property E/G of the soundboard 35 as a whole, its internal friction loss Q-
The frequency characteristic of ' is shown by the solid line a in FIG.

That is, compared to a normal soundboard material (natural material such as stainless steel material) shown by the dotted line in the same figure, the internal wear loss Q increases particularly in the high frequency band. In this way, by increasing the internal wear loss Q-' in the high frequency band,
High-frequency component noise that is easily radiated as sound is reduced, and the timbre is improved. In addition, it is required as a piano soundboard.
Regarding Young's modulus such as E/γ or E/γ3 (where γ is density), and other density-dependent acoustic properties,
is almost never damaged. Therefore, the round holes 37, 37. By forming ・, it is possible to obtain characteristics that are equal to or better than those of high-quality natural materials generally used for piano soundboards, and the overall sound ``resonance'' and ``warmth'' characteristic of wood sound are sufficiently achieved. will be obtained.

Furthermore, in the configuration described above, each round hole 3737,
・Since the drilling interval changes along the grain direction M,
By setting the values of the timbre-related material physical properties E/G to the respective optimum values according to the sound generation range of the soundboard 35, the tone quality balance between the respective sound generation ranges can be set to an optimal state. That is, the piano is a musical instrument with a very wide range, and the required sound quality differs depending on each range.

In particular, in the high range, a gorgeous and extended sound is required, and in the low range, a natural sound that is not heavy and metallic is required.Tone-related material properties E/G mentioned above
The improvement in sound quality obtained by increasing the value of is particularly effective in the bass range. These sound quality trends are determined by the driving position of the soundboard 35 by the strings, that is, the long bridge 40.
Considering that this is largely related to the structure and material of the soundboard 35 in the vicinity of the support position of each string, the long bridge 4 is
The round holes 37, 37 . By gradually increasing the interval between holes of ... and gradually decreasing the increase in the value of the timbre-related material property E/G as you move toward the higher range,
It is possible to optimize the tonal balance between the tonal ranges unique to the piano.

Next, FIGS. 22 to 24 are diagrams showing the configuration of a modification of the third embodiment described above, and in this modification,
Each round hole 37, 37. The diameter and drilling interval of ... are constant, and only the depth changes along the wood grain direction M, and the soundboard 35
The depth gradually decreases as the string support position moves toward the treble side.

Further, FIGS. 25 to 27 are diagrams showing the configuration of another modification of the third embodiment of the present invention, and in this modification, each of the round holes 37, 37. The depth and formation interval of ... are constant, and only the diameter changes along the grain direction M,
The diameter becomes gradually smaller as the position of the string support portion of the soundboard 35 moves toward the treble side.

However, in Figures 22 and 25, the long piece 40
illustration is omitted. Even in these modified examples,
From the low range to the high range of the soundboard 35, each round hole 37,3
7. By gradually decreasing the depth or diameter of ..., the timbre-related material physical properties E
The degree of increase in the /G value is gradually reduced, thereby optimizing the balance of sound quality between the tonal ranges unique to the piano.

According to the third embodiment described above, each round hole 37°37,.
Since at least one element among the diameter, depth, and drilling interval (or number) of The characteristics can be arbitrarily set according to the sound generation range of the soundboard 35, and thereby the value of the timbre-related material physical property E/G of each part of the soundboard 35 can be set artificially and freely. can.

[Fourth Embodiment] FIG. 28 is a plan view showing the overall configuration when the fourth embodiment of the present invention is applied to a grand piano. -B' cross-sectional view and arrow C
Perspective views seen from this direction are shown in FIGS. 29 to 31.

In these figures, the soundboard 35 is made up of a plurality of straight-grained wood veneers 36.36. . . are assembled in the width direction, and the longitudinal direction of each straight-grained wood veneer 36, 36, . . . coincides with the grain direction M thereof. and,
In the inner layer portion of each contact surface 36a, 36a, .・ are drilled in each. Each of these round holes 57, 57. . . ., the drilling intervals P+, P* + P 2 + . . . are 36.36. . . . The drilling interval P varies from the center to the periphery of the soundboard 35. Pt
, P a, . . . are set to gradually increase. Here, in FIGS. 29 and 30, the long bridge 40 provided on the upper surface of the soundboard 35 and the baton 41 provided on the lower surface are shown, but in FIG. 28, these illustrations are not shown. is omitted.

The above-mentioned round hole 57.57. To explain the processing method for..., first, each straight-grain wood veneer 36, 36. As shown in FIG. 32, each straight-grained wood veneer 36, 36. A round hole 57.5 with a constant diameter and a constant depth is formed in the contact surface 36a of . . . along the neutral axis in the thickness direction.
7. ... are drilled at regular intervals, and in this case, each straight-grained wood veneer is 36.36. ..., round holes 57, 57. ...
The drilling interval is P1. P t, P s, . . . As a result, the grain direction M of the straight-grained wood veneer 36,
Rows of round holes 57, 57, . . . extending in substantially orthogonal directions are formed. In this way, round holes 57.57. The soundboard 35 is fabricated by joining the straight-grained wood veneers 36.36° in the width direction and gluing them together as shown in FIG. 33.

In the above configuration, the planar projected area of the entire soundboard 35 is S
Assuming that the cross-sectional area (effective area) including the neutral axis of the soundboard 35 is So as shown by diagonal lines in FIG.
, 57. By appropriately setting the diameter and depth of the material, the strength against shear deformation of the material, that is, the property equivalent to the transverse elastic modulus G, can be set to approximately S'/S (<1) times. As a result, the value of the timbre-related material physical property E/G, which is the ratio of the longitudinal elastic modulus E and the transverse elastic modulus G of the soundboard 35, can be increased to a desired value.

In this way, by increasing the value of the tone-related material property E/G of the soundboard 35 as a whole, its internal friction loss Q'
-' frequency characteristics are as shown by the solid line a in FIG.
57. By forming ..., it is possible to obtain characteristics that are equal to or better than those of high-quality natural materials used for piano soundboards, and the overall sound "resonance" unique to wood materials, warmth, etc. will be obtained in sufficient quantity.

Furthermore, in the above-mentioned configuration, each round hole 57°57,
The drilling interval for each straight-grained wood veneer is 36.36°.
・Since each is different, by setting the values of the timbre-related material physical properties E/G to the optimal values from the center to the periphery of the soundboard 35, the sound quality balance in the low to treble region can be optimized. can be set in the state. That is, the piano is a musical instrument with a very wide range, and the required sound quality differs depending on each range. In particular, in the high range, a gorgeous and extended sound is required, and in the low range, a natural sound that is not heavy and metallic is required.

Considering that these sound quality trends are largely related to the vibration modes occurring in the soundboard 35, each round hole 57, 5
7. ... drilling interval P 1. Pt, Ps.

By gradually changing the timbre-related material property E/G and appropriately setting the degree of increase in the value of the timbre-related material property E/G, the degree of freedom in designing the tonal balance between the tonal ranges unique to the piano, and thus the individuality of the tonal quality, increases.

In addition, in the fourth embodiment described above, the drilling interval P
1. We have made P t, P z, ... gradually larger toward the periphery, but if we make them gradually smaller, for example, as shown in the modified example of Fig. 41, another unique sound quality can be obtained. .

Next, FIGS. 35 to 37 are diagrams showing the configuration of a modification of the fourth embodiment described above, and in this modification,
Each round hole 57, 57. The diameter and perforation interval are constant, and only the depth differs for each straight-grained wood veneer 36°36..., and the depth gradually increases from the center to the periphery of the soundboard 35. It is small. In addition, as another modification, as shown in FIGS. 42 to 44, if the depth is gradually increased toward the periphery, it is possible to realize a tone having a different personality.

Next, FIGS. 38 to 40 are diagrams showing the configuration of another modification of the fourth embodiment described above, and in this modification, each of the round holes 57, 57. The depth and drilling interval of ... are constant, and only the diameter of each straight-grained wood veneer is 36.36. ...
The diameter is different from each other, and the diameter becomes gradually smaller from the center of the soundboard 35 toward the periphery. However, the third
5 and 38, illustration of the long piece 40 is omitted. As another modification, as shown in FIGS. 45 to 47, if the diameter is gradually increased toward the periphery, a tone with a different personality will be obtained.

In each of these modifications, the round holes 57, 57, . By gradually decreasing the depth or diameter of ..., the degree of increase in the value of the timbre-related material property E/G is gradually reduced toward the periphery, thereby improving the sound quality balance between the tonal ranges unique to pianos. You can design your own personality.

Thus, according to the embodiment described above, each round hole 57.5
7. ... diameter, depth, and drilling interval (or number)
At least one element of each straight-grained wood veneer 36,3
6. Since the strength against shear deformation of the material, that is, the property equivalent to the transverse elastic modulus G, can be arbitrarily set, this allows the timbre-related material properties E/E of each part of the soundboard 35 to be The value of G can be set artificially and freely.

"Effects of the Invention" As explained above, according to the present invention, since a plurality of spaces are provided inside the soundboard in the thickness direction, the strength against shear deformation of the inner layer of the soundboard, that is, the transverse elastic modulus The property equivalent to G decreases, and as a result, the value of the soundboard's timbre-related physical property E/G can be increased to a value that is impossible with natural materials, producing a warmer woody sound than conventional natural materials. Furthermore, since at least one element of the shape or arrangement of each space is different, each of these elements can be changed as appropriate depending on the bass side string to treble side string support part of the soundboard. As a result, the sound quality balance between each range can be set to an optimal state, and the following effects can therefore be obtained.

■Since at least one element of the shape or arrangement of the winter space is different, each of these elements is changed as appropriate from the center toward the periphery, thereby achieving characteristics equivalent to the transverse elastic modulus G of the inner layer of the soundboard. Each is changed at a predetermined proportion suitable for each,
The value of the timbre-related material physical property E/G of each part of the soundboard can be changed according to each generated sound range, and as a result, individuality of sound quality balance can be obtained.

■Internal friction loss Q- in the high frequency band when driving the soundboard
' becomes large, making it difficult for high-frequency noise components to be acoustically radiated, improving the tone.

■Tone can be improved by an extremely simple woodworking process in which hollows and holes are formed before straight-grained wood veneers are joined together.

■The Young's modulus and other density-dependent acoustic properties required for soundboards are hardly impaired.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the configuration of a first embodiment of the present invention;
Figure 2 is a sectional view taken along line A-A in Figure 1, Figure 3 is a sectional view taken along line B-B in Figure 1, Figure 4 is a view taken along arrow C in Figure 1, and Figure 5. is an enlarged plan view of the veneer in the same example, FIG. 6 is a cross-sectional view showing the groove width in the same example, FIG. 7 is a characteristic diagram showing the frequency characteristics of internal friction loss in the same example, and FIG. 1 is a schematic configuration diagram showing a keying mechanism of a grand piano. FIG. 9 is a plan view showing the configuration of the second embodiment of the present invention, FIG. 1θ is a sectional view taken along line A-A in FIG.
Figure 1 is a sectional view taken along line B-B in Figure 9, Figure 12 is a view taken along arrow C in Figure 9, Figure 13 is an enlarged plan view of the veneer in the same example, and Figure 14 is a cross-sectional view taken along the line B-B in Figure 9. It is a sectional view showing the groove width in the same example. 15 is a plan view showing the configuration of a third embodiment of the present invention, FIG. 16 is a sectional view taken along line A-A' in FIG. 15, and FIG. 17 is a sectional view taken along line BB' in FIG. 15. 18 is a perspective view taken from the direction of arrow C in FIG. 15, FIGS. 19 and 20 are a partial side view and a partial plan view for explaining the processing steps of the same embodiment, and FIG. 21 is a partial cross-sectional view of the same embodiment along the center line in the thickness direction, FIG. 22 is a plan view showing the overall configuration of a modified example of the same embodiment, and FIG. 23 is a view taken along A-A in FIG. 22.
Fig. 24 is a sectional view taken along the line BB' in Fig. 22, Fig. 25 is a plan view showing the overall configuration of a modification of the same embodiment, and Fig. 26 is a sectional view taken along the line AA'A' in Fig. 22. 27 is a sectional view taken along the line BB' in FIG. 22. Further, FIG. 28 is a plan view showing the configuration of a fourth embodiment of the present invention, FIG. 29 is a sectional view taken along line A-A' in FIG.
Figure 0 is a sectional view taken along line B-B' in Figure 28, and Figure 31 is a cross-sectional view of Figure 2.
A perspective view seen from the direction of arrow C in Fig. 8, Fig. 32, and Fig. 3.
3 is a partial side view and a partial plan view for explaining the processing steps of the same embodiment, FIG. 34 is a partial sectional view along the center line in the thickness direction of the same embodiment, and FIG. 35 is a partial cross-sectional view of the same embodiment. A plan view showing the overall configuration of the modified example, FIG. 36 is AA'A of FIG. 35.
Figure 37 is a cross-sectional view taken along line B-B' in Figure 35;
FIG. 38 is a plan view showing the overall configuration of another modification of the same embodiment, FIG. 39 is a sectional view taken along the line AA'A' in FIG. 35, and FIG. 40 is a sectional view taken along the line BB' in FIG. 35. 41 is a plan view showing the overall configuration of another modification of the same embodiment, FIG. 42 is a plan view showing the overall configuration of another modification of the same embodiment, and FIG. 43 is the same as that of FIG. 42. 44 is a sectional view taken along line BB' of FIG. 42, FIG. 45 is a plan view showing the overall configuration of another modification of the same embodiment, and FIG. 46 is a sectional view taken along line A-A'. A-A in Figure 45
47 is a sectional view taken along the line B-B' of FIG. 45. 1.35... Soundboard, 2.36... Straight-grain wood veneer, 36a... Contact surface, 5.25... Groove, 37.57... Round hole, M...grain direction.

Claims (6)

[Claims] (1) A wooden musical instrument soundboard having a plurality of spaces provided inside the board in the thickness direction, and in which at least one of the shape or arrangement of the plurality of spaces is different. soundboard. (2) In a musical instrument soundboard made of a plurality of straight-grained wood veneers intersected together, the inner layer of at least one of the contact surfaces of the plurality of straight-grained wood veneers is coated along the grain direction of the inner layer. 1. A soundboard for a musical instrument, characterized in that a hollow part is formed in the wood, and the width of the hollow part is made different in a direction orthogonal to the grain direction. (3) In a musical instrument soundboard made of a plurality of straight-grained wood veneers intersected together, the inner layer of at least one of the contact surfaces of the plurality of straight-grained wood veneers is coated along the grain direction of the inner layer. 1. A soundboard for a musical instrument, characterized in that a hollow portion is formed in the wood, and the width of the hollow portion is varied along the direction of the wood grain. (4) The musical instrument soundboard according to claim 3, wherein the width of the hollow portion gradually increases in the direction of the wood grain. (5) In a musical instrument soundboard formed by intersecting a plurality of straight-grained wood veneers, at least one inner layer of each of the contact surfaces of the plurality of straight-grained wood veneers that contact each other is provided with a layer that corresponds to the direction of the wood grain. A plurality of holes are drilled in substantially orthogonal directions, and at least one element among the diameter, depth, and drilling interval of each hole is varied along the grain direction. Soundboard for musical instruments. (6) In a musical instrument soundboard formed by intersecting a plurality of straight-grained wood veneers, at least one inner layer of each contact surface of the plurality of straight-grained wood veneers that abuts each other is provided with a layer that corresponds to the direction of the wood grain. A plurality of holes are bored in substantially orthogonal directions, and at least one element among the diameter, depth, and drilling interval of each hole is different for each of the straight-grained wood veneers. Soundboard for musical instruments.