Timbre and the perceptual organization of musical patterns

Abstract

Timbre, usually defined as the condition of attributes other than pitch, loudness, and duration, plays a strong role in determining the perceptual organization of musical patterns. Timbre's primary organizational influence appears to be on perceptual grouping, as in auditory stream segregation and rhythmic segmentation. Grouping by timbre can influence the tonal implications of otherwise ambiguous pitch material. Extensions of the author's previous work on the perception of timbral analogies demonstrate that timbre melodies and timbrally based phrasing and articulation can exhibit invariances similar in character to the manner in which pitch patterns exhibit perceptual invariance under transposition. With the strong organizing influence of timbre in mind, it is argued that care should be taken in experiments on melodic and rhythmic organization to control for the influence of timbre. Pure tones and fixed spectra exhibit a strong correlation between fundamental frequency and measures of the location of the spectral envelope, an important timbral determinant and are inappropriate for many experiments on music perception. A simple set of procedures for preparing stimuli with independent control of spectral envelope, temporal envelope, and frequency content is provided and demonstrated.