The sound from one string on a violin is essentially periodic. So, can apply Fourier series. When do that, get the amplitudes of the overtones. The periodic s

The sound from one string on a violin is essentially periodic. So, can apply Fourier series. When do that, get the amplitudes of the overtones. The periodic sound from a violin string is not a sine or cosine wave, but, as in Fourier theory, each of the overtones is. And it is just those overtones a violinist uses to tune the instrument. That is, use a tuning fork to tune the A string to, say, 440 Hz. Then bow the A string and the E string together, listen to the third overtone from the A string and the second overtone from the E string and adjust the E string until the beats (for each x Hz difference in frequency, x beats a second) disappear. The overtones being used are the sine-cosine components in the Fourier series decomposition of the periodic sounds.