Timbre

Timbre is the qualitative characteristic of sound that, for example, permits a listener to differentiate one instrument (e.g. a clarinet) from another (e.g. a bassoon) even when the two are producing the same pitch .  The difference in quality of sound (i.e. ‘sounds like a clarinet’ vs. ‘sounds like a bassoon’) is the difference in timbre (Seashore, 1938/1967).  The different timbres of musical instruments are due to differences in combinations of harmonics.  When an instrument plays a particular note, it generates a tone that has the fundamental frequency of f hz.  It will also generate overtones at frequencies of 2f hz, 3f hz, 2f hz, and so on.  The quality of tone that is experienced is the result of summing all of these different waveforms together.  However, the amplitude of each harmonic overtone will be different; timbre is the perceptual result of summing together  overtones weighted by amplitude.  Different timbres results by changing the relative weights of the various harmonics.  Seashore reports the harmonic analysis of the timbres of a variety of instruments.  He reports, for instance, has high amplitude partials in the neighborhood of 500 hz, and in low notes, higher weightings for higher harmonic frequencies.  In contrast, the clarinet does not have any particular frequency of harmonics that have typical high amplitudes, and its odd-numbered harmonic frequencies have higher weightings than do its even-numbered harmonic frequencies.  The flute generates a tone that is almost pure, with almost all of its energy devoted to the fundamental frequency, and hardly any weighting of harmonics.  “This perhaps is the characteristic to which we refer when we speak of any tone as being flutelike” (Seashore, 1938/1967, p. 189).

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