Name:Mila Bertolo

School/Affiliation:McGill University

Co-Authors:Storch, D. S., Weiss, M., †Peretz, I., †Sakata, J. T. († contributed equally)

Virtual or In-person:In-person

Abstract:

Music is characterized cross-culturally by small integer ratio rhythms, such as isochrony (i.e., the regular pulse of a ticking clock). Given isochrony's ubiquity, there has been extensive investigation into its biological basis. One theory predicts that species capable of vocal learning would also display isochrony. We test this question by comparing isochrony in the spontaneous song of humans and another vocal learner species – zebra finches, a songbird that learns to produce a complex and stereotyped song. Spontaneous song is an understudied but important aspect of music performance that is intuitive enough for non-musicians to engage in, and represents an ecologically valid expression of musicality. We find evidence for significant isochrony (i.e., greater than expected by chance) in the spontaneous song of non-musician adults (n = 15, 24-82 years old) and children (n = 38, 3-10 years old). In contrast, surprisingly, we find that zebra finches produced songs that are less isochronous than expected by chance (n = 73 finches). Given that humans' rhythm priors are influenced by experience, we also tested whether the birds’ degree of isochrony expression was dependent on isochrony in their tutor’s song. Despite that the acoustic structure and sequencing of acoustic elements are learned in finches, we did not observe significant learning of this rhythm. These findings reveal an important species difference; despite both humans and zebra finches being vocal learner species, zebra finches do not appear to produce isochrony above chance or learn it, whereas humans display this behaviour even at young ages and without musical training.