Violin Physics

[Moose352]

I play the violin, and I recently figured out that if I very gently touch my finger on a string, it produces a higher integer multiple of the frequency if I were to hold my finger down all the way. How does this happen?

[Hurkyl]

It's called a harmonic. When a string vibrates, it vibrates at all integer multiples of its natural frequency, and these multiples are called harmonics. When you lightly press the string, rather than changing the length of the string, you are merely suppressing the harmonics that would have that part of the string move.

For example, take the G string. Its fundamental is a low G, it's first harmonic is a middle G (twice the frequency), its third harmonic is a high D (three times), then a high G, B, D, and so on.

Now, if you lightly touch the string at the one-third point (or the two-thirds point), that is where you'd put your finger to play a middle D, then you prevent all the harmonics that would move the one-third point. In particular, this leaves you with every third harmonic. In this case, the lowest frequency you get is a high D, and you get all the harmonics of the high D.

[kuengb]

I play the violin, and I recently figured out that if I very gently touch my finger on a string, it produces a higher integer multiple of the frequency if I were to hold my finger down all the way.
This way of playing has a name: Flageolett. Also used on other string instruments.

It's not like I play the violin or something, I heard this expression in a physics lesson :rolleyes:

[The Bob]

It's called a harmonic. When a string vibrates, it vibrates at all integer multiples of its natural frequency, and these multiples are called harmonics. When you lightly press the string, rather than changing the length of the string, you are merely suppressing the harmonics that would have that part of the string move.

It is the same for all stringed instruments. Harmonics apply to all of these. Harmonics also apply in differnet ways on all insturments but that is another thread.

The Bob (2004 ©)