JPS60159894A - Sound plate percussion instrument - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a tone plate percussion instrument that prevents the generation of a rasping sound and can be easily tuned.

[Prior art]

Tone plate percussion instruments such as marimba, chirofuon, viplaphone, etc.
Both have wooden (or metal) tone plates that have a natural frequency and are arranged in the order of scale from low to high.

This is played by hitting it with a mallet. Therefore, the tone plate is the most important part that determines the sound quality characteristics of the instrument itself, and is generally made of hard wood and formed into a rod-shaped body with a rectangular cross section, with an arc-shaped or double bridge in the center of the lower surface. A mold shape is formed.

The bar is supported by strings, elastic pillows, etc. at two nodes located at both ends, and both ends are free.

Here, let us explain the vibration of the tone plate from the perspective of acoustics.

It can be explained as the vibration of a rod. The vibration forms of the rod are divided into three types: vertical vibration of the rod (1), lateral vibration of the rod (1), and torsional vibration of the rod.In conventional tone plate percussion instruments, among these three types B, especially (H) ) Designed mainly for lateral vibration.

It is tuned.

Therefore, to explain in detail about transverse vibration, this is vibration that occurs in the direction perpendicular to the longitudinal direction of the rod, and vibration in the thickness direction (
flexural vibration) and widthwise vibration (horizontal flexural vibration). Horizontal bending vibration has a large stiffness in the width direction of the rod, so
The vibration amplitude is significantly smaller than the deflection vibration in the plate thickness direction.
Generally, it is based on flexural vibration. Therefore, here, unnecessary flexural vibrations will be simply referred to as vibrations.

Most of the tone plate percussion instruments correspond to the above-mentioned toshi-ryo-bite-free par. So, strike the center of a straight stick with both ends free and no holes in the center of the bottom surface.

Assuming that it is vibrated, the vibrations shown in FIGS. 1(a) and (d) will occur. In other words, (a) in the same figure is the -order vibration (fundamental vibration), (b) is the secondary vibration (first upper tone), (0)
indicates the third-order vibration (second supertone), and (d) indicates the fourth-order vibration (third supertone). If l is the total length of rod 1, then the -order vibration in (a) is 0.2241 from both ends! The point is the fulcrum (node) P,
The center of the rod 1 becomes the belly due to the spring action. therefore,
It can be seen that the center and both ends vibrate violently.

Therefore, by weakening the force of the shibane that excavates this antinode, the frequency is changed and the natural frequency of the tone plate is obtained. In this case, the amplitude increases because the plate thickness becomes thinner.

Similarly, in the case of second-order vibration, its fulcrum (fIDP) increases at three places at both ends, J ( It is common knowledge.

The general formula for the transverse vibration of the front bar (when solved using the Oy 2-Bernoulli formula) is the first frequency f (1) μ Approximately the following formula % formula % However, π is pi, l is the rod The length of is a constant (4,
730), ρ is the density, and E is Young's modulus.

Therefore, the -th frequency (fundamental frequency) f, is the above formula Ki
By substituting =1, it becomes.

Also, if you add the frequency fttfs 1f4 K which is higher than the secondary vibration.

ft”s2・Q fs””r”・Q f4=9ζ・Q From the above, the higher-order vibration line a! , 5R, 7! ,
g! It is determined by the square of an odd number such as...
If f 1 = 3”・Q is 1, the frequency ratio of each higher-order vibration to the first-order vibration is 1:2.756:5.4
04:8.933... is a non-integer multiple.

Therefore, when designing an actual tone plate, this secondary vibration (2
, 756) to 4.00, and at the same time, the third-order vibration (5,404) is tuned to 10.00. As a specific method, the second
As shown in the figure (&), a generally arc-shaped groove 3 is formed at the center of the lower surface of the tone plate 1 to obtain a natural frequency, and to suppress higher-order vibrations such as secondary, tertiary, etc. I have to.

However, even if such a groove 3 is formed, the occurrence of a muffled sound becomes a serious problem in a specific range of sound.

Research on this noise has been very slow, and the method of correcting it is close to fiK, and the effects of small-amplitude horizontal bending vibrations have not been considered at all, but recent research has shown that
The actual situation was that it was discovered that this horizontal flexural vibration had an effect.

In other words, in addition to the vibration in the thickness direction (flexural vibration) of the tone plate mentioned above, it is also possible to vibrate in the width direction (horizontal flexural vibration). )
It has been found that there are many cases in which a noticeable rattling noise is produced when the horizontal deflection primary vibration (fundamental vibration in the width direction) and the horizontal deflection primary vibration are close to each other. This noise condition occurs when the frequencies of the secondary flexural vibration and the primary horizontal flexural vibration are approximately +20 cents to -20 cents (excluding +180 cents to -180 cents). (Excluded because it does not sound like a sound)
When both of these vibrations fall within this range, it is felt as a muddy sound, and in order to prevent this from occurring, we have empirically determined the cross-sectional shape of the central part of the tone plate as shown in Figure 2 (b). cl +
(d) Changed as shown in K. However, there were many problems in preventing this phenomenon, as listed below.

(1) Even the tone plate where K polyphonic notes should not occur.

If there is no intermediate sorting of the tone plates, a specific range of tone plates will be processed all at once, taking into account variations in the tone plates in order to compensate for out-of-tuning, and conversely, many notes will be generated. is.

(1) Even if the sound is clear, the sound is thin and the tone differs from the surrounding tone plates, creating a strange feeling.

(1) Attenuation is fast and there is no extension in the sound. The volume also decreases.

Qv) The yield of tone plates is poor and the cost is high.

(Vl Both sides of the center part of the tone plate are very thin and may crack or chip when struck.

(vI) The horizontal bending vibration (number) also decreases, but at the same time, the primary and secondary vibrations of knitting also decrease, so it takes a lot of skill to match these three vibrations to the target frequency. Therefore, manufacturing costs are high.

[Summary of the invention]

This invention was made in view of the above points,
A multi-cut groove is provided near the center of the side of the tone plate.

By lowering the frequency of the primary vibration of horizontal deflection, it is possible to prevent the generation of noise and increase the sound pressure and volume, and it is easy to manufacture and tune without requiring any skill, and can be provided at low cost. It is intended to provide tone plate percussion instruments that can be obtained.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

〔Example〕

FIG. 3(b) is a side view and an enlarged sectional view taken along the line at-■, showing an embodiment of the tone plate according to the present invention.

In the figure, reference numeral 10 denotes a wooden tone plate formed into a rod shape with a predetermined length, thickness, and width, and an arc-shaped cutout 11 is formed at the center of the lower surface of the tone plate 10.

Reference numerals 12m and 12b are small holes formed at the nodal points of fundamental vibration of the tone plate 180, and these small holes 12a.

12bK A string or the like that supports the tone plate 10 is inserted.

Usually, the tone plate 10 is vibrated (
(first-order vibration of deflection) and higher-order vibration (secondary vibration of deflection).

Third-order (vibration) tuning is performed to give the desired natural frequency. However, regarding the tone plates (particularly the tone plates in the mid-range range) where the post-tuning deflection secondary vibration and the horizontal deflection primary vibration are generated, the cutting groove 13. which characterizes this invention.
14 are formed near the center of both sides of the tone plate 10 in addition to the grooves 11. In this case, although the present embodiment shows the case where the cut grooves 13° 14 are formed in the longitudinal direction of the tone plate 10, the present invention is not limited to this, and the cut grooves 13° 14 can be formed in the plate thickness direction.
The width and depth of a specific part of the cut groove may be changed, or it may be formed only on one side or at an appropriate angle (30' to 60 mm).Also, the length of the cut groove 13, 14 may be changed.

The width, depth, and number are set depending on the positions of the secondary flexural vibration and the primary horizontal flexural vibration, and therefore differ for each tone plate.

In other words, both vibrations are within ±20 cents or ±1801
The length, width, depth, etc. are changed so that the frequency is at the 80 cent point 2. As a result, the frequency of the secondary flexural vibration hardly changes, and the frequency of the primary horizontal flexural vibration decreases. This was confirmed through experiments.

Figure 4 is a diagram showing the frequencies of bending vibration and horizontal bending vibration.
When correction processing is performed, bending vibrations (f, , f, , f.

...) remains as it is, and the frequency of the horizontal bending vibration Cf,,',to,f,/...) moves horizontally to the left from the chain line position. and sft and f,
What is I?

It will be within -20 to +20.

Figure 5 shows the damping characteristics of the primary vibration of horizontal deflection with the same sound pressure level; (a) the current tone plate without the h-cut grooves 13 and 14; The tone plate according to the present invention has the following characteristics. As is clear from the figure, in the tone plate according to the present invention, the primary vibration of horizontal deflection is attenuated faster than in the current tone plate, and the effect is less.

Figure 6 (al, (bl) shows the attenuation characteristics of the primary flexural vibration f and the secondary flexural vibration f. Figure 6 (a) shows the attenuation characteristics of the primary flexural vibration (f,) with the sound pressure level aligned. In the figure, A is the current tone plate without the Ni-to-9 sound, B is the current tone plate with the Ni-to-9 sound, and C is a tone plate that prevents the Ni-to-9 sound according to the present invention. In addition, Figure (b) shows the damping characteristics of the secondary bending vibration J,) with the same sound pressure level, and A and B overlap each other.As is clear from the figure, the present invention According to the tone plate CK, the sound pressure level of 8+ft is the current tone plate A.

It is higher than BK and maintains damping for a long time.

Figure 7(a) + (bl, (cl is a diagram showing the attenuation characteristics of the tone plate, (al is the current tone plate with a simple gouge,
2(b) is a current tone plate with a cross-sectional shape of a boat as shown in FIG. 2(b), and FIG. 2(C) is a tone plate according to the present invention. In the current tone plate shown in FIG. 6(a), the attenuation is fast and a burr is produced.

In addition, nigo 9 sounds are also generated. The tone plate according to the present invention shown in FIG. 4(C) does not generate ni and 9 tones, has very few undulations, and decays very slowly compared to the current tone plate shown in FIG. 4(b). Also, the vibration width is large.

This is due to the effect of the cut p grooves 13 and 14,
The horizontal flexural primary vibration (f,') can be more than 200 ce/t) stronger than the flexural secondary oscillation (f2).

The nine-tone sound disappears, making the sound clear. Also, if the Nigo 9 sound disappears, the vibration energy loss due to SunajDK will decrease,
The damping of the primary flexural vibration (f,) and the secondary flexural vibration (f,) is maintained for a long time. In other words, the sound becomes longer. Therefore, since the sound pressure is high and the volume is also increased, the sound and flow of the low and treble parts are smoothed.

The processing and formation of the cut grooves 13 and 14 is shown in FIG. 2(b).

Compared to the cross-sectional shape of the current tone plates shown in (0) and (d), which prevents the nine-note sound, this has the advantage of being significantly simpler and easier, requiring no skill, and making it easier to match the target frequency. Therefore, in addition to workability, yield is improved, making it possible to reduce manufacturing costs.

Furthermore, since the thickness of the central portion of the tone plate 10 is not changed, it does not crack or crack when struck, and has excellent durability.

〔Effect of the invention〕

As described above, the tone plate percussion instrument according to the present invention has cut grooves formed approximately at the center of the sides of the tone plate to lower the frequency of the primary vibration of horizontal deflection.

Due to the secondary deflection vibration and the above-mentioned horizontal deflection primary vibration, generation of 9 tones can be reliably prevented and good tuning can be achieved. In addition, by preventing the 9-tone noise, vibration energy loss is reduced and the sound becomes more elongated, so the sound pressure and volume increase, and clear sound can be obtained. In particular, the occurrence of the nine-tone sound is noticeable in the mid-range tone plate, which worsens the relationship between the low and high-range sounds, but if the tone plate according to the present invention is used in the middle range, this problem can be solved. This can improve the performance of the instrument. Furthermore, the cutting grooves are easy to form, do not require skill, and are easy to match with the 'Wr constant frequency.
Yield p is improved and an inexpensive tone plate percussion instrument can be provided.

[Brief explanation of the drawing]

FIGS. 1(a) to (d) are diagrams showing the vibration form of the rod, and FIGS. 2(a) to (d) are side views and sectional views of the central part of the current tone plate. FIGS. 3(a) and 3(b) are side views showing one embodiment of the tone plate according to the present invention, and an enlarged cross-sectional view along the line ■-■. FIG. 4 is a diagram showing frequencies of bending vibration and horizontal bending vibration. , Figure 5 is a diagram showing the damping characteristics of horizontal deflection primary vibration, Figure 6 (a),
7(b) is a diagram comparing the damping characteristics of the primary bending vibration and the secondary bending vibration, and FIG. 7(IL) + (b) + (c) is a diagram showing the damping characteristic of the tone plate. 10...Tone plate, 11...Egusi, 12a, 12
b...small hole, 13.14...cut groove. f,... secondary vibration of deflection, 8'... primary vibration of horizontal deflection. Patent applicant: Nippon Musical Instruments Manufacturing Co., Ltd. Representative: Masaki Yamakawa (and 2 others) Figure 6 IchisakiFll'l (t) Figure 7

Claims (1)

[Claims] A tone plate percussion instrument characterized in that a cut groove is provided in the center of the side surface of the tone plate to prevent the generation of a K-thud sound.