The "wolf sound" exists in the whole family of stringed instruments, but the vibration of the wooden board is smaller and easier to control than the wolf sound produced by the vibration of the skin. Wolf sound is a difficult problem to solve in erhu performance. Now the way to suppress the wolf sound of the erhu is to put a sponge under the bridge. Although this method is effective, it has a certain impact on the timbre and volume of the erhu.

For the suppression of the erhu wolf sound, I have done a little experiment to prove that the skin tightness of the erhu, the strength and angle of the bow, and the proper selection of the bridge and horse all have an impact on the generation and suppression of the wolf sound.

It is necessary to mention here that the definition of wolfyin is not listed in the "Cihai" and "Encyclopedia of China Physical Volume", this is because the term is too specialized. In my opinion, beginners of erhu are unlikely to encounter wolf sounds, but noise. It is precisely because the definition of wolf sound is not clear that noise is mistaken for wolf sound.

In fact, there is a difference between wolf sound and noise. I think the difference is firstly manifested in the fact that the wolf sound mostly occurs in the vicinity of half of the string, while the noise may appear anywhere on the string. Secondly, the timbre of the wolf tone is somewhat similar to the overtone, but it is obviously different from the overtone: the overtone is that the finger must be pressed in half, one third, one quarter of the string... The plucked strings can be played, the pitch is stable, and the timbre is clear and transparent. The wolf sound is the sound played by the finger really pressing on the string. It can be seen that the general erhu beginners encounter noise, and it is unlikely that it is the sound of a wolf. The main reason is that this noise will not only appear near half of the string, but may occur in any position, and the lower position is more serious. Then there is the difference in the control difficulty of noise and wolf sound: if you can control the wolf sound, you must be able to control the noise, but those who can control the noise may not be able to control the wolf sound well.

The wolf sound is present on all stringed instruments. It is familiar to anyone who plays stringed instruments, and no physicist does not know it. So why doesn't "Encyclopedia of China·Physics Volume" accept this term? It also makes sense to think about it. The sound has opposing musical tones and noises, as well as real tones and overtones, so this wolf sound is obviously not a musical tone, nor an overtone. Is it noise? Not like. How should physicists define it? The author suspects that the timbre of the "Dong Xiao" imitated in "The Sound of Xiao Jing in the Night" played by the blind musician Sun Wenming is probably the alienation of this "Wolf Sound". When Mr. Sun Wenming was a part-time student in the Ethnic Music Department of the Shanghai Conservatory of Music, he majored in flute. Mr. Sun's erhu art failed to attract the author's attention. Unfortunately, none of Mr. Sun's descendants can master the charm of Mr. Sun's performance. The author intends to discuss this issue in "Sun Wenming's Erhu Performance Art". Here we are still discussing the control of erhu noise. Controlling the noise is not far from controlling the wolf sound.

The reason for the noise on the erhu, in addition to the improper production and accessories of the erhu, is that the speed of the bow is not matched with the strength of the bow. For beginners, remember this point: in addition to the speed of the bow must be uniform, the force of the bow must be matched with the force of the bow, otherwise it is very easy to produce noise (instead of wolf sound). This is the reason why even the best erhu often produces "creeping, screeching" noises for beginners. At this time, it should be noted that the slower the bow is moved, the smaller the force of the bow pressing the string should be; the greater the force of pressing the string, the faster the bow must be pushed and pulled. In addition, the strength of bowing and closing should be small when playing. The changes of strength and speed during the whole bowing process are in the shape of an olive with two small ends and a large middle: the bowing speed at both ends is slow, the strength of pressing the string is small, and the strength in the middle is small. The bigger the bow, the faster the speed of the bow; the stronger the playing, the greater the ratio of the amplitude between the two ends and the middle, but the process of changing from weak to strong during strong play is very short, but it cannot cancel this process of change.

In addition to being extremely familiar with the relationship between bowing speed and strength, I have proved through actual verification that the direction of bowing (that is, the angle between the bow rod and the piano rod) is also sufficient for noise and timbre. influences. Every erhu has an optimal angle, and this angle can also change slightly by moving the position of the bridge. The author suspects that Mr. Gan Tao took advantage of this relationship and improved the sound of the erhu with the bow. The author has seen Mr. Gan Tao's discussion on the erhu, but unfortunately, Mr. Gan has not mentioned the issue of Lang Yin. The author has stayed in Shanghai since he was admitted to the Department of Ethnic Music of the Shanghai Conservatory of Music in 1959, and has been out of the music industry for decades. Now that Master Gan has passed away, he can only find out for himself.

The noise and wolf sound on the erhu may also be affected by the skin (snake skin). On what basis? You think, when the erhu is made, whether the barrel is round, hexagonal or octagonal, the tension around the barrel is always equal. But after the bridge is suppressed by the tension of the strings, will the tension around it be equal? At this time, the tension around the membrane is not equal, and the vibration of the membrane cannot be balanced. How can there be no noise and wolf sound? It is a fact that people often put a sponge under the bridge, and the noise and wolf sound will be suppressed to a certain extent at this time.

In order to improve the sound quality of the erhu, I have done a more detailed study on the Qinma. Extraordinary thinking is necessary to solve this problem. The author once made a special horse for a huqin with a very noisy sound quality using color wood, and the sound quality has been greatly improved - there is no sponge under the horse, as long as the bow is carefully carried, the third one will not make any noise. This shows that the Qinma plays an important role in the sound of the erhu. It should be noted that the production of this horse took three days, and the price seems to be a bit too expensive, but if we continue to study, the second and third... don't need so much time, right?

From the above facts, it can be inferred that not only the strings below a thousand pounds and above the bridge are vibrating during the performance, but the strings at the bottom of the bridge are also vibrating, and the vibration of the strings at the bottom of the bridge deteriorates the sound quality of the erhu. I have achieved the purpose of improving the sound quality of the erhu through the choice of the height of the bridge and the base of the bridge. In addition, I tilted the bridge slightly upward to reduce the pressure on the strings at the lower end of the bridge. The two strings are gently tied together to dampen the vibration of this small section, which also further improves the sound quality of the erhu.

Regarding this issue, my research is very superficial, and I will disclose it here in order to attract the attention of performers. If this article can be a little helpful to the beginners of Erhu, and can become a brick for experts to further study, my goal will be achieved.