Vokalisointitehtävien rakenne ohjaa sydämen säätelyä ja interpersonaalista fysiologista synkroniaa kuorolaulussa

In choral singing, the heart is simultaneously regulated by respiratory sinus arrhythmia and autonomic responses to the demands of performance. This makes it difficult to separate the effects of top-down cognitive and motor effort from the bottom-up mechanics of breathing. To disentangle these mechanisms, this study investigated how varying vocal task structure and visual contact alter individual cardiac regulation and interpersonal physiological synchrony. Sixteen singers (four quartets) performed four tasks of varying demands (spontaneous conversation, freeform improvisation, monophonic unison, and polyphonic counterpoint) in facing and back-facing conditions, with cardiac and respiratory signals analysed for heart rate variability (HRV) and surrogate-corrected phase synchronization. Transitioning from conversation to structured singing systematically increased cardiovascular arousal and reduced overall HRV, suggesting that the integrated cognitive and motor load of performance overrides the bottom-up mechanical effects of structured breathing, whereas visual contact yielded no significant autonomic changes. At the interpersonal level, structured musical scores acted as external pacemakers of breathing, driving high respiratory and cardiac phase-locking between singers. In contrast, improvisation generated above-chance cardiac synchrony despite the absence of a shared musical score. These results indicate that top-down autonomic regulation drives individual physiological states during performance, while both shared musical structure and active co-creation guide interpersonal physiological coupling. Given that these individual and interpersonal physiological dynamics reflect more than the mechanical effects of breathing, future research should integrate physiological measures with subjective psychometrics to investigate how these dynamics relate to the psychological experience of joint musical performance.