# EXPLORATION OF TIMBRE **Opening (not a real abstract):** Timbre refers to the quality of sound. It is the perceptual attribute that enables us to distinguish among orchestral instruments that are playing the same pitch and are equally loud. But, unlike loudness and pitch, timbre is not a well-defined perceptual attribute. Definitions tend to indicate what timbre is not rather than what it is. Take as an example the following enigmatic definition provided by the American National Standards Institute (1960, p. 45): "Timbre is that attribute of auditory sensation in terms of which a listener can judge that two sounds similarly presented and having the same loudness and pitch are dissimilar." The notion of timbral constancy or invariance is even vaguer than that suggested in the definitions of timbre as a basis for discrimination. It would seem that a form of timbral constancy is implied by the common observation that a sound **Authors:** [[ANALYSIS AND SYNTHESIS JEAN]]