Processing of pitch and time sequences in music

Pitch and duration -- either as written symbols or in auditory form -- are the basic structural properties in tones that form a melodic sequence. From the cognitive perspective, it is still a matter of debate whether, and at which processing stage, these two factors are processed independently or interdependently. The present study addresses this issue from the neuroscientist's point of view by measuring event-related potentials (ERPs) in musicians and non-musicians. Either the pitches or the durations of the tones, or both, were permuted randomly over a set of melodies in order to remove all sequential ordering with respect to these factors. Effects of both, pitch and time order, on the peak amplitudes of the P1-N1-P2 complex were observed. ANOVA revealed that sequential processing may depend on the different levels of skill in analytical hearing. For musicians, strong interaction effects for all three ERP components corroborated the interdependence of pitch and time processing. Musicians also seem to rely on coherent time structure more than non-musicians and showed enlarged P1 and P2 components whenever tone duration, either with or without preserved pitch, was at random. Non-musicians tend to use ordered pitch relations for perceptual orientation, and main effects without any interactions might indicate some kind of independent processing of both dimensions at some processing stages.