The idea that Chinese performers on Chinese instruments playing Chinese music might be guilty of whitewashing seems preposterous, yet I'm going to suggest that whitewashing occurs here, and to no small extent.
Within China, over the past close to two centuries, with Westernisation of the Chinese society, European culture has become the idea of a representation of high culture, modern organisation, a system focused on scientific rigour and understanding. This perceptual shift is a widespread movement throughout various levels of the Chinese society and not restricted to music alone. Western science, western systems of thought, and even western musical systems were being hailed as advanced, as the direction the Chinese had to go in order to be a part of the modern world. This was understandable, with China losing out swathes of land and power since the Opium Wars to the Europeans. What was in the past an ancient and powerful civilisation was so reduced, it was inevitable the Chinese believed that a different way of government, education, philosophies, an entire different way of doing things had to be implemented for their civilisation to be on par with the rest of the world.
Music was no different. The early 20th century saw promotion of singing in schools, bringing music education to the younger generation of Chinese. What is known as school-songs (学堂乐歌) were in fact Westernised melodies with new lyrics. Music education reform was carried out by many idealistic individuals who had the opportunity to go abroad to further their studies. Having learnt the musical tradition of European art music and seeing its systematic organisation of theoretical knowledge, most of them wholeheartedly embraced these philosophies, believing that this was the reform that the Chinese culture needed. From the early 20th century onwards, music in China took on a whole new set of ideas, philosophies, aesthetics, and structure. This was not to say that traditional Chinese music was totally wiped out or that the philosophies and aesthetical ideas of the past few thousand years no longer influenced the people, but it was a fact that this new music from Europe impacted the ideas and musical culture of China significantly from the early 20th century.
While there is the constant revival, conservation and work done for the folk and classical traditions of China, it is an indisputable fact that a significant extent of the idea that people have of Chinese music is the music of the "Chinese orchestra". The development of the Chinese orchestra will not be detailed here but readers can be directed here for slightly more detailed description of its development.
With the basic premise of the Chinese orchestra modelled upon the symphony orchestra of European art music tradition, the aesthetics of how the sound should be like is gradually being influenced as well. The full Chinese orchestra set up as we know of now is not built from a single group of instruments from a particular folk instrumental ensemble, but from different kinds of ensembles all around China. One difficulty arising from this is the fact that these instruments were not built to blend together because they did not originate within the same ensemble in the first place.
Within folk instrumental ensembles, there are various instruments that have very unique sounds and it is precisely because of these unique sounds that contribute to the particular ensemble's defining characteristic. When they come together in the Chinese orchestra however, all these various characteristic sounding instruments unfortunately might not work very well together. In attempting to emulate the symphony orchestra, instruments are being grouped into four instrumental families, much like the instruments in the symphony orchestra. With the creation of these instrumental families, it is inevitable that people also tend to parallel them in comparison.
Take the bowed string section for example. Although both groups of instruments produce sound through the bowing of strings, the similarity pretty much ends there. While performers especially competitive young professional musicians fresh from years of gruelling training from the conservatory will like to emphasise that whatever the violin can do, so can the erhu, and that is quite true - almost all the violin techniques can be performed on the erhu, and there are numerous technically virtuosic pieces in the violin repertoire that have been played just as well by performers on the erhu - they are still fundamentally different instruments. The structure of the instruments are very different with the erhu sounding with a membrane versus the wooden soundboard of the violin. There is no fingerboard on the erhu as well and the angle the bow makes on the strings is different from that of a violin. With all these fundamental differences, it is a sad fact of life that many erhu performers still take the ability to perform virtuosic pieces from the violin repertoire as one of the important goals in erhu performance. While finding ways to challenge and break technical limits is important and always welcome, it is unfortunate that sometimes it overshadows other forms of achievement in the performance of a Chinese musical instrument.
Chinese instruments have been seen as being built less scientifically than western musical instruments. Although this idea is slowly changing, it is nevertheless a very deeply ingrained one. The idea of musical instruments from another culture being less "well-built" is hard to shake off when the standard is being set with the ability to perform pieces equivalent to the European art music repertoire in musical systems based on the European art music culture. Definitely it is a boost to the ego when one can say that one is able to perform a certain piece of music just as well on the erhu as any other good violinist can on the violin, it is unfortunate however that this in fact perpetuates the believe that for the musical culture of the Chinese to be good, one as to aspire towards the achievement of European art music standards. This in fact is a circularity that turns in on itself. Instrument makers and researchers are at the same time constantly developing various ways of improving on Chinese musical instruments and many of the improvements sought after are precisely how to make them "comparable" to western musical instruments. Making instruments whose sounds "blend" better together in the orchestra, trying to increase the instruments' resonance and sound (an erhu can never match a violin in terms of volume) and even experimenting with different materials for the instruments are some examples of these developments. The results are instruments that sound good in the orchestra, instruments which are easier to play, and so on, and these are definitely welcome for performers. But at the same time, is "sounding good in an orchestra" a very Eurocentric point of view? What does a "good sound" imply?
All these build up an extremely intricate web that is very difficult to unravel. With the development of the Chinese orchestra being so influenced by European art music, the direction musical aesthetics of the Chinese orchestra takes has already been set, from the early days. While not set in stone, it is still a direction which, unless the entire performance practice of the Chinese orchestra were to change radically, is still going to be moving in the same general course. Yet at the same time, even with its borrowing of all the European traditions, there are elements that are different. While I argue that the whitewashing of Chinese music is a matter of historical fact, I am also at the same time, believing that music, art, and culture are always evolving, and always borrowing from other traditions and cultures. With communications and huge ease of accessibility, this is going to be even more so in the current time. And that should not be something to be feared but recognised. Influences should be acknowledged and new developments embraced.