In this third lecture, we looked at the perception of rhythm, another major attribute of musical perception. The notion of the perception of time in music, and more specifically of rhythm, was introduced. One of its characteristic features, which we illustrated using sound examples, is the perception of beats when listening to a regular flow of notes. This perception, which underlies the grouping of notes into measures, can be induced by sound cues (variations in intensity, pitch or time intervals between notes), or can even occur when listening to a stream of identical notes.
We then reviewed current knowledge on the development of rhythm perception in children (Winkler et al., 2009), which contributes to the debate on the role of innate and acquired factors in sound perception. The psychoacoustic characteristics underlying rhythm perception were discussed, in particular the fact that rhythm in complex music is generally associated with the low note line, while melody is more likely to be carried by the high notes (Hove et al., 2014).
We then turned to current research into the neurophysiological mechanisms of rhythm perception (Grahn, Rowe, 2009), and first to the identification of the brain structures involved. We have considered the mechanisms involved in rhythm perception, for which two theories have been proposed, known as "interval or internal clock theory", and "entrainment or brain oscillator theory". The current experimental basis for each of these theories has been examined, with the former attempting to shed light on the existence of neurons whose activity reflects a response to rhythmic time (Merchant et al., 2011; Crowe et al., 2014), and the latter on the role of brain oscillations in rhythm perception (Fujioka et al., 2012). Finally, continuing our lecture on the evolution of musical perception, we discussed the evolution of rhythm perception across species (Patel, 2014).
