Early electrophysiological correlates of meter and rhythm processing in music perception

The two main characteristics of temporal structuring in music are meter and rhythm. The present experiment investigated the event-related potentials (ERP) of these two structural elements with a focus on differential effects of attended and unattended processing. The stimulus material consisted of an auditory rhythm presented repetitively to subjects in which metrical and rhythmical changes as well as pitch changes were inserted. Subjects were to detect and categorize either temporal changes (attended condition) or pitch changes (unattended condition). Furthermore, we compared a group of long-term trained subjects (musicians) to non-musicians. As expected, behavioural data revealed that trained subjects performed significantly better than untrained subjects. This effect was mainly due to the better detection of the meter deviants. Rhythm as well as meter changes elicited an early negative deflection compared to standard tones in the attended processing condition, while in the unattended processing condition only the rhythm change elicited this negative deflection. Both effects were found across all experimental subjects with no difference between the two groups. Thus, our data suggest that meter and rhythm perception could differ with respect to the time course of processing and lend credence to the notion of different neurophysiological processes underlying the auditory perception of rhythm and meter in music. Furthermore, the data indicate that non-musicians are as proficient as musicians when it comes to rhythm perception, suggesting that correct rhythm perception is crucial not only for musicians but for every individual.