Design Review of the Erhu

The Erhu is the traditional Chinese violin and is also referred to as a spike fiddle, belonging to the Huqin instrument family, as well as being classified as a traditionally bowed zither.

The instrument body is compiled of two tuning pegs, the neck, a hexagonal resonating box that is hollowed out and open at one end, a membrane composed of either lizard or snake skin, two strings and a bow. Popularly played as a solo instrument either on stage or on the street, it also used in ensembles, the two types having different registers. The Gaohn is higher pitched, whilst the Zhonghn is the lower. The instrument itself has been prevalent since the 12th century and has undergone developments in response context and purpose, and has also been subject to technological solutions for practicality.

One of the first noted responses to how the Erhu was played was the bow. The bow is never separate from the strings, passing between them not over them. They are meant to be as if there were one, the inside string being closest to the player is generally tuned to D4 and the outside to A4, a fifth higher. The bow itself used to be made out of silk, like the strings of the instrument itself, but changed to horsehair after it was exemplified by Europe and its design response to the violin. Having done this, it also managed to produce a finer sound, giving variation and breadth as well as intensity, especially useful within the context of an orchestra.

Another contextual response is that of the skin of the animal used for the membrane on the hexagonal resonating body and the woods used for its construction. An ordinary Erhu makes use of simple snakeskin, whilst a higher quality would use that of a boa,

“The most important part of the Erhu is the python skin, the reverberations of the skin give the Erhu its unique sound.” (Yang Youlin, 2005)

High quality woods are also used in their making, mainly in the neck of the instrument. Adding to the quality, particularly, is the sentimentality of the wood being used, in that it is said by some that if the Erhu is produced from furniture of the house of the user its worth is increased.

Although the body shape and design of the Erhu has managed to maintain itself, there have been considerations in its design and interface as to how players interact with it as well as its potential in many different forms of expression.

The Erhu’s main forms of expression come from the bow and strings’ tandem design and how they coincide with another. One famous player, Liu Tianhua, was able to re create many sounds because of this. In particular, his portamento style allowed him to produce an uncanny likeliness to birdsong. As well as the glissando and vibrato techniques employed in its playing, another form of playing is referred to as “hopping”. This is the act of bouncing the bow between the strings and reproducing the sounds of drops of water, creating “light hearted and warm dynamics” (Sachs 1968).

One other design consideration is that of the wood that the instrument is produced from. Varying dense woods are considered in the making of the Erhu, including redwood, aged redwood, blackwood and red sandalwood. However, the finest wood considered is rose wood. Its use, particularly in the shaft, is used to gain a “pure sound”.

The Erhu consists of only so many segments whilst its design and playing are credited with lots of manipulations in dynamics and technical playing, allowing the instrument its famous sounds of a weeping woman, horses and birdsong. These have been allowed to develop because of the technological solutions, giving it practical implementation as an instrument.

The most important feature of this instrument is it’s resonate body. Over the years the material of the box has changed from bamboo to coconut, and finally settled on denser, heavier woods. The resonant features of the body’s open-closed tube build have a significant effect on the tonal quality of the Erhu. Having it closed at both ends would produce a significantly muted sound, not suitable for ensembles especially. It is also important to note that the hexagonal box doesn’t resonate, unlike other instruments’ sound chambers, notably the violin. The box essentially is there to help amplify certain frequencies. It is in fact the taught serpentine skin that when vibrating, because of the strings, produces the wail, “…acting like a speaker” pushing air and creating loud sound waves.

A man named Benade designed a graph, in which he sketches the frequency response and resonance curve of violins, detailing that the main air resonance would enhance the violins D string and that the wood would enhance the A string. There is a small parallel one can draw form these sketches, particularly the act of the air amplifying the note, D. this is important to note only because of the open end of the sound chamber of the Erhu but also the general openness of the instrument, allowing this amplification.

Resonance curve

Benade’s resonance curve displaying typical behaviour of resonances.

Another technological transition is the reform of the older style strings. Traditionally the strings were composed of twisted silk, but at the turn of the 20th century there were attempts to standardize and exemplify the Erhu, with the explicit aim of making it louder, better and more solid. This came in the form of introducing steel strings instead of the twisted silk. By the 50s, the thinner A string had been replaced by the E string of the violin and tuned accordingly, but the thicker D string was still retained. By 1958 however, professional players were using the purpose built steel strings, the trend catching on almost as fast as the change of bow strings.

Another developed technology was the qian jin. This was a small piece of string wrapped around the neck and the strings of the Erhu and acts as the nut and pulls the string closer to the skin as well as holding the bridge in place. The qian jin holds the bridge in place so it can perform essentially two tasks. Firstly, it provides space for the bowing of the instrument. As well as this, it also helps to transfer a lot of the energy from the vibrations of the strings to the sound box, allowing it to produce as much sound as possible. This is essential for playing in small ensembles, unlike in larger ones where the Erhu may be amplified.

The Erhu seems to respond a lot to contextual and purposeful designs. This can be viewed in such a way that one could say the instrument is one of stubborn history and prefers to maintain a traditional figure and technology. The membrane itself is an especially good example of this in that there have been no exceptions in the use of serpent skin. There are farms specifically breeding snakes for Erhu membranes. Wood is also very important with emphasis on the fact that if the piece is created from existing furniture it becomes more valuable.

However it is important to note the small but significant technological implementations allowing for a physical, playable instrument. One of the most important features being the qian jin, not to mention the open-closed tube aspects of the Erhu’s sound chamber. In tandem with those, the practice of standardising the strings of the Erhu was extremely important in terms of creating an amplified and audible sound.

Finally, the design considerations of the instrument are essentially what give the world-renowned image of an integral element of a Chinese orchestra. The integral tandem design of the strings and bow are what allow for the glissando and vibrato expressions of the instrument, reproducing many dazzling aural effects.

Although the Erhu is compiled of only so many segments and structures, it is the contextual, technological and design considerations of which it is made of that have allowed the manufacturing of this iconic instrument.



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