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An Introduction to Traditional Chinese Musical Instruments and Research Exploring the Principle of

Chinese Wind Instruments

Dachuan Xiao UIUC Physics 193 Fall Semester, 2012

China is a country with a long history. Chinese music can be dated to 7000 years ago. There are mainly two types of musical instruments in Ancient China, wind instruments and stringed instruments. We give a brief introduction about the principles and the characteristics of traditional Chinese musical instruments.               There are just five basic notes in ancient Chinese music, they are Gong, Shang, Jiao, Zhi, Yu which 

are stands for do, re, mi, sol, la or C,D,E,G,A. Although the social status of singers and musicians was low 

at that time, the ancient Chinese zither, a stringed instrument which was invented about 2500 years 

ago stands for a civilized social status of a gentleman. At that time, a noble or a rich family required the 

children to study Chinese zither, Chinese chess, Chinese calligraphy, and Chinese painting. When

a musician plays the instrument, he uses his right hand to pluck the string and left hand to adjust

the tension of the string.

Red sandalwood and silver filament Chinese zither

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Zhu Geliang, a famous military consultant in Chinese history, who is regarded as the icon of wisdom of China. The picture shows him playing Chinese zither on the gate tower to pretend there is an ambush in the city but actually there is no army in the city. His excellent and peaceful performance makes his enemy dare not to attack since his performance shows his confidence. Like all the other string instruments, the Chinese zither produces sound by the vibration of the string and the sound is enlarged by the resonance of the wooden plate. To raise or lower note of the Chinese zither, the player can adjust the pitch of the string by increasing or decreasing the tension of the strings or by touching the string to change the length of vibration. The Chinese zither cannot produce very loud sounds. Unlike the guitar or other stringed instruments, the Chinese zither is designed for narcissi, which means the purpose of the player is to amuse himself. Therefore, the Chinese zither music is implicative of morbidezza - extreme softness and delicacy, pure and fresh. The pace of zither music is usually long and slow which is aimed for lasting appeal but sometimes vigorous deep. The meaning of the music is usually the appreciation of the natural life and peaceful mind which agrees with Zen and Daoism.

The principle of the Chinese zither There are two fixed points of each string. The mechanical wave which is generated by the pluck of the hand will be reflected at these fixed points. The overlap of the reflected wave and the progressive wave causes the vibration of the air and therefore produces the sound. Because the zither is put on a desk when it is played and the arrangement of the strings, Chinese zither music usually imitate the flow of water by plucking the string from the first one the last one continuously. One of the famous Chinese zither music is called "Mountain Stream". The music first imitate the sound of droplets by plucking several strings together and then increase the times and the string number of the plucking to imitate the sound of the stream. Finally, the player moves his hand rapidly from the first string to the last for several times to imitate the sound of the fall and at this time, the music and the emotion of the player are brought to a climax.

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Pipa

If the Chinese zither stands for a gentleman, the pipa is designed for a beautiful girl. The note range of the pipa is wide and difficult playing skill is required during the performance. In the late Tang Dynasty, the performer played the pipa with fingers instead of a plectrum and the neck of the pipa was widened; the resonance bow was changed from thick to thin. These changes increase the range of the notes of the pipa and made a big improvement of the pipa in the history. The reason why these change makes the pipa have a wide range of note can be explained by the experiment I did. I will talk about my experiment after the introduction of the instruments.

This is a picture which refers to a famous beauty at the end of Han Dynasty. At that time, the pipa was played like guitar while in the Tang Dynasty, the pipa was played in a vertical position sitting on the lap and on the left side of the player.

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Xun

An ancient egg-shaped holed wind instrument In my perspective, it is the most miraculous instrument in Chinese history and also it is one of the earliest wind instruments in China. The performance of such an old instrument could be seen on the ceremony in the past and only the emperor has a big instrument band which includes all the types of old instrument. The principle of this instrument seems like that of the flute, but the egg shape makes me confused. However, I won't explore too much on the details of the egg-shape wind instrument in this project. Whatever the shape of these instruments or whether they are wind or string instrument, the material (wood) is really important for them to give loud and nice sounds. As we know the more smooth the surface, the more efficient the reflection. In another word, we can not use the material made for absorbing sound in the auditorium to make an instrument.

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My assumption is: The quality of the sound given by the instrument mainly depends on the density of the material which is used to reflect the sounds. In my knowledge, red sandalwood or rosewood is the good material to make an instrument since they have more density than other kind of woods. A piece of good rosewood won't float on the surface of water, unlike other normal woods, it sinks in water. This demonstrates that the density of rosewood is greater than water and therefore greater than other kinds of wood. In addition, the age of tree is another factor which determines the density of the wood in spite of the kind of the tree.

The Experimental Measurements

Professor Errede helped me to record and analyze the sounds of blowing bottles. First, I blow an empty glass bottle, then a glass bottle filled with some water (no more than half of the volume of the bottle), then a glass bottle filled with more water but not full( more than half of the volume) Second, repeat the first step but use a plastic bottle. When I blow the bottle, I found it is easiest to blow the empty one, and then the one filled with some water, the most water filled is the hardest to blow.

Glass bottle empty

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Glass bottle fill 1

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Glass bottle fill 2 By comparing the harmonic range of glass bottle with different fill I found, the frequency of the harmonic increase with the increase of the amount of water. We could also use equations to derive such a conclusion. First, since the surface of the water increases, the distance of the sound wave reflection decreased.

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As we know the wavelength of the harmonics is determine by the distance of reflection of the length of the "string",(For example, the wave length of the fundamental harmonic is twice the length of the string) although there is no string, we could ignore the cross sectional area of the bottle and the distance from the bottleneck to the surface of the water is the length. The speed of the sound is a constant here since I did this experiment in almost same room temperature and density of the air cannot change drastically. The product of wavelength and frequency is the speed and the wavelength decreases with the decrease of the reflection distance. Therefore, the frequency increases with the decrease of the wavelength for each harmonic. The less the water fill, the smaller the frequency of the harmonics. Such a conclusion makes me think about the violin and the viola and the cello, the bigger the "belly" or the space for the sound wave to reflect, the lower the frequency of the sound. When I first saw a concert, I wondered why they don't make the instrument smaller for easy handling, now I know for a small instrument; the length of the instrument is not enough for it to make a low sound. And also this is the reason why in Tang Dynasty, for increasing the note range of the pipa, the volume of the instrument was made bigger. Let’s see the condition of the plastic bottle.

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Plastic bottle empty

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Plastic bottle fill1

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Plastic bottle fill2 The phenomenon is the same that the bigger the space in the bottle, the higher frequency of the sound. Another found is that sound quality of the plastic bottle is not as good as the glass bottle. Let’s see one amplified graph.

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The frequency of the fundamental, the second, the third, the fourth harmonic of the glass bottle fill1 We could see the average frequencies: 212.455, 426.412, 631.6995, 841.322 are almost multiple integer of 212.455(212.455, 212.455*2.007, 212.455*2.9733. 212.455*3.9600) This means the notes of the glass bottle is accurate. In another word, if we could adjust the volume of the bottle, it could be a instrument. On the other hand, the plastic bottle:

The frequency of the fundamental, the second, the third, the fourth harmonic of the plastic bottle fill1 The average frequencies are 237.95, 487.23, 730.8455, and 965.9625 (237.95, 237.95* 2.0476, 237.95* 3.0714, 237.95* 4.0595) They both seem good. But if we see the harmonic of other graphs

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Glass bottle

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Plastic bottle Now plastic bottle is not as good as glass bottle since the lines in the graph is not as straight as that of the glass bottle. This is why that a good instrument use nice rosewood and has a higher price because old tree is time-costly. In addition, my calculation of the harmonic frequencies is just based on the range but actually I need to consider the distribution of the values in the range. It is pity that I cannot play any traditional Chinese instrument but this cannot stop my love of the culture of China. Although I don't have any Chinese instruments I have learned the fundamental principles of this instrument. In this way, I could understand them not only in a perspective of culture but a view from physics which is also my major.