The role of competing grouping patterns and tonal coherence in neural synchronization to musical meter.

Musical meter emerges from the hierarchical organization of beats, which is influenced by both external acoustic cues and internally driven processes. This study examines neural and behavioral responses to auditory sequences when two simultaneous grouping patterns, melodic repetition and intensity accents, are candidates to establish a ternary or quaternary metrical representation. We also investigated how tonal coherence and tempo affect these metrical representations. To do so, we recorded finger tapping responses and electroencephalograms (EEG) from musically-naïve participants while they listened to musical sequences. The frequency-tagging analyses of the EEG indicated that melodic repetition, compared to intensity accents, enhances neural synchronization to metrical groupings. In contrast, disrupting tonal coherence with microtonal intervals reduces neural responses to both grouping patterns. No neural synchronization to any of these patterns was observed during a grouping-continuation imagery task. Behavioral data from the tapping task revealed a strong preference for quaternary over ternary groupings. These findings provide evidence that a repeating melodic pattern can establish neural responses to its periodicity, which likely scaffolds a metrical representation of the rhythmic sequences in the brain through complex interactions between bottom-up and top-down mechanisms in the formation of musical meter.