The Perception Of Rhythm And Tempo Modulation In Music

Research is presented on the perception of rhythm, specifically, the detection of changing or modulating inter-onset intervals in simple musical stimuli. The types of changes of rhythmic patterns examined are rhythm modulation and tempo modulation. These two terms are akin to the musician\u27s concepts of agogics, rubato, accelerando and ritardando, all being common expressive devices in musical performance. Rhythm modulation occurs when an initially even or isochronous rhythm becomes increasingly more uneven. Tempo modulation occurs when the beat rate of a rhythm accelerates or decelerates.;Two approaches are adopted to elucidate how such modulating patterns might be perceived, a theoretical one and an experimental one. Following a review of the pertinent literature, a theoretical model of time-interval perception in music is proposed that attempts to synthesize the findings of previous experimentation. The main thrust of the model is that rhythm perception is mediated by two complementary processes: (1) a so-called OSCILLATOR BANK that entrains to stimulus time-intervals on a note-to-note basis, and (2) a SHORT AUDITORY STORE that is responsible for integrating temporally separated events.;The model generates the hypothesis that rhythm modulation will be detected in the OSCILLATOR BANK, whereas tempo modulation will be detected in the SHORT AUDITORY STORE. This hypothesis is tested in three perceptual experiments. To compare the difficulty of detecting rhythm and tempo modulation under various conditions, certain variables are manipulated: the direction of modulation (whether a change onset occurs earlier or later than expected), the initial beat rate, the metrical location of modulation, and the presence or absence of beat subdivision. To measure perceptual difficulty, a type of reaction-time dependent variable and a modulation-type-identification dependent variable are used.;The following results are observed: (a) the direction of modulation is significant only for tempo modulation, (b) rhythm and tempo modulation exhibit contrasting trends across the musical initial-beat-rate range, (c) metrical location does not affect detection and (d) detection is easier with beat subdivision. These results are generally consistent with the hypothesis that rhythm and tempo modulation detection are mediated by contrasting perceptual processes