How to choose Erhu is a hot topic among Hu friends. For many years, there have been many stories about painting, long stories and short stories, giving people the feeling of seeing flowers in the fog. I often encounter masters who have played the piano for decades and masters who have made the piano for decades, and sometimes the words are vague. It seems that the purchase of musical instruments really requires us to have some knowledge of the acoustics, materials, mechanics, and production technology of musical instruments. Only on the basis of erhu performance can we truly know what we know. The experience of buying erhu and the friends of the piano are as follows:

1. Check the resonance focus area of the piano barrel

As the jargon says, the sound of a good qin should be "tethered", which means that the resonance of the erhu drum must form a focus, otherwise the sound will be scattered and lackluster, empty and unreal, the treble is empty and the bass is thin. After the piano skin vibrates and sounds, the sound wave is extended and focused into a pyramid-shaped waveform area along the mouth of the piano obliquely to the bell mouth. The length of the pyramid-shaped waveform changes according to the inclination of the bell mouth, plus the reflection resonance effect of the sound groove (the oval piano has no sound groove. ), which has become the key element to adjust the balance of erhu high and low bass. When the high-pitched area (ie, the lower position) moves forward in the resonance focus area, the volume is large and the sound quality is real; when the resonance focus area is moved backward, the volume is small and the sound quality is thin. The bass range (i.e. the top position) is just the opposite. In order to take into account the balance of high and low frequencies, the position of the resonance focus area must be reasonable. Experience has shown that it is better that the resonance focus is a little behind the central axis of the piano bar. The simple way to determine the resonance focus area is: during the audition, the left hand feels the vibration of the piano bar, headstock and piano support, which indicates that the resonance focus is just on the central axis of the piano bar. In addition, we can also hear it empirically. The resonant focus area of erhu.

2. Avoid the "Penny Effect"

When a bamboo penny is intact, it will make a sound of "dangdang" when it is struck. Once a crack in the middle section or the head of the penny is broken, the whole bamboo penny will have a "hissing" sound. The reason is that the broken crack passes through After the resonance, it spreads to the penny to form the "broken penny effect". Erhu's "Penny Effect" phenomenon has not been paid attention to so far. During the production process, natural and artificial gaps will inevitably appear in the material structure of erhu. I have experienced an erhu made of excellent materials. Usually the sound quality is very good, but when I play it quietly at night, I can vaguely hear the unnoticeable "hiss" noise on the d tail of the outer string. I later removed the support plate and found a small air-drying crack on the edge of the barrel with a magnifying glass (old materials are prone to occur). With a little bit of high-permeability 502 glue, the "sizzling" noise is instantly eliminated. The "Penny Effect" generally does not produce noise at the origin, it will transfer the sound of the piano body along with the guided vibration, and often appears in the tail sound of the erhu pronunciation. The "hissing" noise does not appear in all musical sounds, and sometimes it is a certain audio frequency guided resonance of the erhu that just excites the "penny effect". Selection method: 1. When playing the empty strings, use your ears to detect the sound of the piano. You can hear obvious noises in the erhu with the "Penny Effect"; Whether there is a problem of crack damage, so as to avoid the mistaken selection of erhu with "broken penny effect".

3. Pay attention to the problem of inaccurate pronunciation of individual notes

Mispronunciation is a common and frequently-occurring disease of erhu, and it is more common on high-end pianos with thick and tight skins. In the process of playing, there is often a phenomenon that individual sounds or several sounds are obviously not pronounced correctly, and the effect is similar to overtone. Some people mistakenly think that the bow is slipping, but the real reason is that the resonance of the piano barrel and the piano skin is in a certain state. The lack of audio coordination, can not produce good resonance caused by. In response to such phenomena, some qins can be alleviated and eliminated after playing for a period of time, while others cannot. Note: 1. The skin of the piano should be thick and even, and the tension around the skin of the skin should be evenly balanced to form a good vibration; 2. The inner wall of the drum should be smooth and symmetrical, with a smooth and coherent arc to form a good reflection and resonance.

4. pay attention to the expressive power of the erhu

Expressiveness is the essence of erhu. Specifically, we can start testing from two perspectives: First, erhu sensitivity and comfort. High-quality erhu requires a sensitive response, the sound of the bow when the bow touches the strings, the sound quality is pure and full, not sloppy; the piano feels comfortable, giving the player a sense of affinity and fully stimulating the player's musical inspiration. The second is the controllability and potential of the erhu. The qin can perform and play freely according to the player's wishes, without "burst" in strong play, without "boom" in weak play, without "whistling" in high notes, and "pharynx" in low notes. It can play freely in the contrast of sound range and intensity, without feeling "difficult", and has good controllability. Just like a car with strong horsepower that allows the driver to fully enjoy the fun of driving, a good piano should also give the player the feeling of being one with the piano. Expressiveness is a feeling that is not easy to describe but can only be comprehended, and there is no standard or scale for measurement. It needs to be understood and grasped by erhu producers and performers.

5. Pay attention to the penetrating power of the erhu sound

Another important indicator for evaluating the sound quality of Erhu is "penetration". Penetration is the combination of timbre, sound quality, and volume, and it is an important internal quality factor for whether the erhu is excellent or not. My experience: Penetration should be the reflection of the unity and harmony of erhu pronunciation to resonance. Vibration is the source of sound waves, no vibration and no sound - simple physical principles. Analyzing the structure and pronunciation principle of the erhu, it can be found that the sound of the strings is transmitted to the piano skin (vibrating membrane). At this time, the central amplitude of the piano skin is large and the frequency is low, and the amplitude becomes smaller and higher near the edge; the vibration of the piano skin is transmitted to the piano barrel. The echo reflection vibration at the front of the skin has a small amplitude and a high frequency, and the amplitude increases toward the back and the frequency range decreases. Through the resonance of the piano skin and the piano, coupled with the resonance of the piano rod and the piano support, the erhu emits a beautiful sound. In my opinion, the erhu vibration frequency range with good penetrating power should be wide, the main audio frequency is prominent, and the secondary audio frequency is harmonious and coordinated, just like a sound, the coordination of its high, middle and low bass makes the music have penetrating appeal. Large volume does not mean good penetrating power, and the standard of penetrating power does not depend on the improvement of volume. The penetrating power is an important indicator of erhu production skills and quality. There are many ways to test the penetrating power of a piano based on my own experience and feelings, among which there are two easiest methods: first, during the audition process, the left hand of the piano feels that the piano bar, the piano barrel, the headstock, etc. have a relatively Strong sense of tremor, timbre, sound quality, and volume coordination; second, one person plays the piano, and one person listens from near to far, listening and distinguishing erhu pronunciation conduction performance, high-quality erhu pronunciation is long, plump and clear, with strong appeal.