Harmonic Partials:

Most sounds (except sine waves) consist of several separate frequency components which vary (all frequency components of a sound = the spectrum (See also spectralist composers ).Harmonic partials are overtones above the fundamental tone (We hear this as the dominant and loudest part of the sound).The overtones are multiples of a fundamental frequency and are produced because a sounding object vibrates in decreasing fractions as well as its whole length. The particular structure of an instrument affects the strengths and weaknesses of its harmonics. Flute notes lack odd-numbered harmonics for example, which is why they sound mellow and simple.

The amplitude of these overtones becomes less as the series goes higher and the musical distance (intervals) between them gets smaller. The overtone series at the lower end is very close to tones in our tuning system (equal temperament) and played an important part in the evolution of western music.