Proceedings of the Annual Meeting of the Cognitive Science Society

Rhythm the organization of sounds in time is a universal feature of human music. Of the infinite ways of organizingevents in time, human rhythms are distributed categorically. We compared rhythms of classical piano playing and fingertapping to rhythms of thrush nightingale songs. Across species, we found similar common rhythms, as relative durationsof intervals formed three categories: isochronous 1:1 rhythms, small integer ratio rhythms, and high ratio ornaments. Inboth species, those categories were invariant within extended ranges of tempi, indicating natural classes. In all cases, thenumber of rhythm categories decreased with higher tempi. Finally, in birdsong, high ratios (ornaments) were derived fromvery fast rhythms containing inflexible (probably uncontrollable) interval ratios. These converging results indicate thatbirds and humans similarly create simple rhythm categories from a continuous temporal space. Such natural categoriescan promote cultural transmission of rhythmic sounds a feature that songbirds and humans share.