Overtones

Overtones, high additional tones that accompany the fundamental tone and determine the timbre of a complex sound. The frequencies of overtones mostly bear a simple multiple relationship to the frequency of the fundamental tone. The complete series of such overtones stands in relation to the fundamental tone in the ratio 1:2:3:4:5:... fundamental tone overtones Such overtones are called harmonics. Harmonic overtones are found in the sounds of musical instruments (strings, pipes, etc.) and in the sounds of the human voice and animals. Additional tones of vibrating rods, plates, and bells are non-harmonic: their frequencies are not multiples of the fundamental tone. Any periodic complex curve (for example, the pulse curve) can be represented as the sum of a series of sinusoids, each of which corresponds to a simple harmonic oscillation (Fourier's theorem). Their frequencies will form with the first sinusoid, which has the same period as the curve being decomposed, a harmonic series: 1:2:3:4:5... The first sinusoid is called the fundamental, and the others are called upper harmonics.