The role of timbre, pitch, and loudness changes in determining perceived metrical structure

Abstract

The role of differences in pitch, loudness, and timbre as determinants of metrical structures was investigated. A repeated sequence of 12 pure tones was systematically partitioned into 4 groups of 3 tones or 3 groups of 4 tones by introducing changes in F0, intensity, and spectral complexity between sounds at serial positions 1, 4, 7, 10 or 1, 5, 9, respectively. Listeners used a rating scale to indicate if a triple, quadruple, or ambiguous meter was perceived. For changes in only one parameter at a time, perception of rhythmic structure followed the physical markers. When changes in more than one parameter were made concurrently, multiple cues for triple or quadruple meter were available. Coincident changes led to reinforcement of the rhythm demarcated by the points of change. Conflicting changes led to different outcomes: Timbre and pitch changes dominated over a loudness-based accent structure. Pitch versus timbre stimuli were rated as having ambiguous meter. A combination of any two parameters versus the third dominated in determining the metrical structure. The results raise questions about the role of timbre in rhythm perception in general and as a tool for marking metrical units in particular.