Response to Intervals as Revealed by Brainwave Measurement and Verbal Means

The purpose of this study was to enhance understanding of the meaning of the interval as a musical parameter. This was done by examining both verbal reports and brainwave (Event-Related Potential, or ERP) responses to intervals. In an experiment with ERP (the oddball task), we examined the responses of listeners trained in Western music to isolated harmonic intervals. In the verbal experiment, we repeated the ERP experiment and added trials with the same harmonic intervals in different contexts (pairs of melodic intervals and intensities), and we added more categories of subjects. The results of the ERP experiment showed that the response to the intervals to which subjects attended was as follows: a distinct appearance of the ERP component P₃₀₀, whose amplitude was greatest for the dissonant interval (the minor 2nd); smallest for the nonperfect consonance (the minor 3rd); and relatively large for the perfect consonance (the 5th). The opposite relationship was observed for P300 latency — shortest for the 2nd and longest for the 3rd. The response over the left hemisphere was greater than over the right (this preference for the left was smallest with the 2nd). Moreover, the response to intervals to which subjects were not attending was influenced by the type of interval to which they were attending. The results of the verbal experiment partially supported the ERP findings and pointed to factors which compete with the contribution to the sense of salience (or excitement) of the interval; their influence varied with the subjects' musical awareness. Our results indicate that, although musical intervals may be comparable to phonemes in speech, in terms of the possibility of categorization, intervals are loaded with meaning even when presented by themselves without any immediate context.