What is the difference between an overtone and a harmonic?
Harmonic versus Overtone.
A harmonic is any of the integral multiplication of the fundamental frequency.
The fundamental frequency
Let's imagine two identical waves traveling in opposite direction. Let these waves meet each other. The resulting wave obtained by superimposing one onto the other is called Standing wave.
For this system, fundamental frequency
Figure depicts vibrational modes of an ideal string, producing harmonic
An overtone is defined as any frequency produced by an instrument which is greater than the fundamental frequency. These along with the fundamental are also called partials. Overtones can take any value of the fundamental frequency. 1st overtone is called second harmonic and so on.
Those overtones which are integral multiple of fundamental frequency are harmonics as already explained above.
In a resonant system such as a stringed instrument, plucking of string produces a number of overtones along with the fundamental tone. These give the distinct sound of the instrument. If the instruments produced only the harmonics and no overtones, all instruments will sound exactly the same.
All harmonics are stationary waves. In case of overtones all overtones are not stationary waves. Only those overtones which match the frequencies of the harmonics act as stationary waves.