Regional Statistics from 2023 Community-based Severe Trauma Surveillance in the Gyeongnam Region.

Rhythm is one of the basic building blocks of human musicality. In its simplest form, the use of a regular pulse—like the clicking of a metronome, referred to as —is extremely widespread among music traditions. Musicians from Mali, Bulgaria, and Germany all finger-tap to reliably mimic small integer ratio rhythms, where durations of adjacent notes have small integer ratio relationships, such as 1:1 and 1:2; they also show a tendency to simplify complex rhythms (e.g., to 1:1, isochrony). This ubiquity suggests the behavior has some shared, biological basis. Indeed, the ability to clap in time to a perceived isochronous pulse has an identifiable polygenetic basis in humans. The presence of isochrony in the vocalizations of distantly related non-human animal species—non-human primates, birds, frogs, and pinnipeds—further indicate some biological basis to this behavior. To date, however, we have little data concerning whether isochrony is expressed in an ancient and universal musical form—singing—and whether there are comparable expressions of isochrony in non-human species capable of combinatorial, learned vocalizations (as opposed to simple, repeated, innate ones). Here, we present a developmental and comparative analysis of isochrony in human improvised songs, and spontaneous song from a non-human animal capable of learned, complex songs: the zebra finch. Isochrony production is widespread and consistent in human percussive musical behaviors. Musicianship is not a prerequisite: non-musicians’ accuracy in tapping synchronously to isochronous stimuli is on par with that of amateur musicians. When musicians and non-musicians from 15 countries were tasked with reproducing an auditory rhythm by tapping along to it, their “errors” systematically favored isochrony even when it was not originally present in the stimulus. Percussive isochrony emerges early in human development; by 2–4 years old, children’s manual tapping spontaneously show regular rates, and they show full-body rhythmic movements in response to music, though inconsistently synchronized to it. By 6–7 years old, the ability to synchronize to an isochronous stimulus is almost at adult-level accuracy, and this accuracy is well-preserved through aging. If isochrony is as fundamental to human musicality as the above findings suggest, we should also see this rhythm in untrained vocal song. Singing is a universal and spontaneous behavior in humans, and its perception is associated with specific neural networks. Young children create new tunes and adapt familiar ones, and this practice of real-time improvisation is found across many of the world’s musical traditions. Improvisational singing, furthermore, is a methodologically useful tool in that it can be intuitively performed by people with little to no formal musical training, through the lifespan. Western non-musicians’ improvised songs remarkably show pitch use that is consistent with the conventions of Western music. Previous findings of isochrony in corpora that include both instrumental and vocal music suggest that isochrony is likely also present in song, but such corpora include music that is the product of explicit musical training. Instead, the study of non-musicians’ improvised song—in the absence of explicit training or mimicry—can better characterize how spontaneously isochrony may arise in human musical production. We expect that non-musicians’ improvised songs should show isochrony in line with their percussive musical behaviors. Similarly, this trait should emerge around the age of 6 or 7 in children’s improvised songs.