The Music of Speech: Electrophysiological Approach

This experiment was aimed at studying the changes in the brain electrical activity associated with some aspects of prosodic processing and at comparing the results with those obtained for the melodic processing of short musical phrases, by manipulating the F0 of the final word/note. Both musicians and non-musicians were presented with French sentences, ending with prosodically congruous, weakly or strongly incongruous words, and with short musical phrases ending with congruous, weakly or strongly incongruous notes. Both Reaction Times (RTs) and Evoked Related Potentials (ERPs) were recorded. In both the prosodic and melodic conditions, RTs were shorter for strong incongruities than for weak incongruities and congruous completions. ERP recorded in both conditions showed that large positive components (P600s) were associated with incongruous stimuli. Moreover, in both cases, the amplitude of the P600 component was larger, and its latency was shorter, for the strong than for the weak incongruities. Interestingly, an early negative component (N150) develop in response to strong incongruities. For the musicians, this N150 component is clearly localized over right temporo-frontal electrodes, specifically in the melodic condition. For non-musicians, the N150 is more broadly distributed across scalp sites. These results point to strong similarities in the processing of prosodic and melodic incongruities, and a general cognitive process may be at play in both cases. However, they also point to some early differences which may reflect the effects of musical expertise.