Both Isochronous and Non-Isochronous Metrical Subdivision Afford Precise and Stable Ensemble Entrainment: A Corpus Study of Malian Jembe Drumming

Abstract

Most approaches to musical rhythm, whether in music theory, music psychology, or musical neuroscience, presume that musical rhythms are based on isochronous (temporally equidistant) beats and/or beat subdivisions. However, rhythms that are based on non-isochronous, or unequal patterns of time are prominent in the music of Southeast Europe, the Near East and Southern Asia, and in the music of Africa and the African diaspora. The present study examines one such style found in contemporary Malian jembe percussion music. A corpus of 15 representative performances of three different pieces (“Manjanin,” “Maraka,” and “Woloso”) containing ~43,000 data points was analyzed. Manjanin and Woloso are characterized by non-isochronous beat subdivisions (a short IOI followed by two longer IOIs), while Maraka subdivisions are quasi-isochronous. Analyses of onsets and asynchronies show no significant differences in timing precision and coordination between the isochronously timed Maraka vs. the non-isochronously timed Woloso performances, though both pieces were slightly less variable than non-isochronous Manjanin. Thus, the precision and stability of rhythm and entrainment in human music does not necessarily depend on metric isochrony, consistent with the hypothesis that isochrony is not a biologically-based constraint on human rhythmic behavior. Rather, it may represent a historically popular option within a variety of culturally contingent options for metric organization.

Statistical learning and probabilistic prediction in music cognition: mechanisms of stylistic enculturation

“…American 6‐month‐olds show no such difference in processing of isochronous and nonisochronous meters; 12‐month‐olds do show a difference, but it is eliminated by 2 weeks of listening to Balkan music, while this was not the case for U.S. adults . There is also evidence for cross‐cultural differences in rhythm production as a function of enculturation …”

“…126 There is also evidence for cross-cultural differences in rhythm production as a function of enculturation. 128,129 Can such enculturation effects be accurately simulated using computational models? As noted above, rule-based models of meter 9,12,[66][67][68] are not sensitive to experience and therefore cannot plausibly account for enculturation, while approaches that simulate meter perception as emerging from the resonance of coupled oscillators that entrain to temporal periodicities 71,73,130,131 naturally imply an explanation of meter in terms of stimulus structure rather than the experience of the listener.…”

“…Demorest and Morrison capture the effects of the SLH in their cultural distance hypothesis: "the degree to which the musics of any two cultures differ in the statistical patterns of pitch and rhythm will predict how well a person from one of the cultures can process the music of the other." 138 While crosscultural research has found evidence of differences in music perception between listeners as a function of their culture, 40,41,64,65,[124][125][126][127][128][129][139][140][141][142][143][144][145][146] the psychological mechanisms underlying the acquisition of these differences are currently poorly understood.…”

The lower limit for meter in dance drumming from West Africa

“…[4] In some repertoires of West African drumming, the subdivision is non-isochronous, i.e., beat subdivision is structured according to stable periodic patterns of distinct subdivision classes (Polak, 2010;Polak & London, 2014;Polak, London, & Jacoby, 2016). For instance, the jembe piece Manjanin displays a recurrent short-medium-long pattern of the ternary beat subdivision, with the short intervals, but not the medium and long ones, frequently being as short as 80-90 ms (Polak, 2010, Tables 2, 5, and 7; endnote 45).…”

Interpersonal entrainment in Indian instrumental music performance: Synchronization and movement coordination relate to tempo, dynamics, metrical and cadential structure

“…A dissociation between SMS and coordination can be observed in practice: tight synchronization does not guarantee the smooth management of transitions, and vice versa. Nonetheless, previous studies, and theoretical speculation, suggest that metrical position may influence synchronization -specifically, that downbeats show less variability (more precision) in asynchrony than other metrical positions (London, 2012;Polak, London, & Jacoby, 2016). In this sense the interaction between low-level automatic processes and higher-level, culturally mediated processes remains a matter for investigation.…”