Rhythmic context influences the auditory evoked potentials of musicians and non-musicians

In this study, we investigated how rhythms are processed in the brain by measuring both behaviourally obtained ratings and auditory evoked potentials (AEPs) from the EEG. We presented probe beats on seven positions within a test bar. Two bars of either a duple- or triple meter rhythm preceded probe beats. We hypothesised that sequential processing would lead to meter effects at the 1/3 and 1/2bar positions, whereas hierarchical processing would lead to context effects on the 1/3, 1/2 and 2/3bar positions. We found that metric contexts affected behavioural ratings. This effect was more pronounced for rhythmic experts. In addition, both the AEP P3a and P3b component could be identified. Though metric context affected the P3a amplitudes, group effects were less clear. We found that the AEP P3a component is sensitive to violation of temporal expectancies. In addition, behavioural data and P3a correlation coefficients (CCs) suggest that temporal patterns are processed sequentially in nonmusicians but are processed in a hierarchical way in rhythmic experts.