– Sounds may be generally characterized by pitch, loudness, and quality. Sound “quality” or “timbre” describes those characteristics of sound which allow the ear to distinguish sounds which have the same pitch and loudness. Timbre is then a general term for the distinguishable characteristics of a tone. Timbre is mainly determined by the harmonic content of a sound and the dynamic characteristics of the sound such as vibrato and the attack-decay envelope of the sound.
Some investigators report that it takes a duration of about 60 ms to recognize the timbre of a tone, and that any tone shorter than about 4 ms is perceived as an atonal click. It is suggested that it takes about a 4 dB change in mid or high harmonics to be perceived as a change in timbre, whereas about 10 dB of change in one of the lower harmonics is required.
– the characteristic quality of a sound, independent of pitch and loudness, depending on the number and relative strengths of its component frequencies, as determined by resonance.
Sounds in Communication 