Then check out this article from Plus Magazine by J. Woodhouse and P.M. Galluzzo. They give some nice illustrations of why a violin sounds different than a guitar, as well as why beginning violinists have so much difficulty producing an “acceptable” sound. They key, apparently, is to find a happy medium between a “surface sound” and a “raucous” sound, called the Helmholtz motion:
There are now two travelling corners on the string, and there are two episodes of slipping per cycle of the vibration. The result is a note at the same pitch as the Helmholtz motion, but with a different waveform and a different sound. For whatever historical reason, this sound is not regarded as acceptable, at least by Western classical violinists. Your violin teacher is likely to dismiss it as “surface sound”, and tell you to practise more until you learn not to do it. The switch from Helmholtz motion to this double-slipping motion sets a minimum acceptable level to the bow force, the force with which the bow is pressed against the string.
There is also a maximum acceptable bow force. If the bow is pressed too hard, instead of a musical note the violin may produce a raucous “graunch” noise. The vibration of the string is no longer regular, but switches to a chaotic pattern. Needless to say, this sound is also disapproved of by violin teachers.
I’ve played the violin since I was 10, and I can easily say that it takes more than a few years of practice to successfully avoid those unacceptable sounds on a consistent basis. Anyone who has learned the instrument or has kids learning to play will be familiar with the scratching and screeching that accompanies a beginner. To demonstrate the difference, I present a begginer (30 seconds worth…they make those beginning tunes short for a reason):
And a master – Heifetz, Melodie by Gluck (I picked this one because you can really see how he changes the angle, speed, and relationship of the bow to the bridge to get varied sounds…all while still achieving the “Helmholtz” motion. He’s also really good at masking the sound of his bow changing directions, which is more difficult than it might seem):
These ideas of “acceptable sound” also play an important role in determining the playability, and thus value of an instrument or bow:
Everyone knows that some violins are a great deal more valuable than others. Why does this happen, when all normal violins appear to be very similar? One aspect of this is “beauty of sound” from the instrument, which is very difficult to address in scientific terms because you first have to find out what a listener means by beautiful sound. However, if you watch a violinist trying out instruments, you may hear comments like “I don’t really like the sound of this one, but it is very easy to play”, or “This one sounds good but it is very slow to speak”. Players are not only interested in sound quality, whatever that may mean precisely, but they are also interested in ease of playing – the playability of the instrument. If one violin is more accommodating than another, in terms of producing Helmholtz motion more reliably or faster, then that violin is likely to be preferred by a player.
I’ve gone through the process of upgrading to a better instrument on a couple occasions, so I definitely agree that some instruments are just easier to play. A more expensive bow just does things for you – a bow stroke that used to take a lot of effort and concentration happens more effortlessly with the better bow. Or you may be able to get a more diverse range of sound that your previous violin couldn’t attain. That always fascinated me – some instruments definitely sound better, but a better instrument provides a range that you couldn’t previously imagine, and allows you to experiment more with your technique and have more “tools” to apply to a piece. Anyway, the article is fascinating for anyone interested in how a bowed instrument produces sound, particularly if you like a bit of the mathematical approach.
Article: “Why is the violin so hard to play?”