Neuromagnetic representation of vowel prosody in the auditory cortex.

A key feature of vowels in spoken language is that their fundamental frequency (f0), which underlies perceived pitch, can change dynamically over time. However, it remains elusive how such prosodic glides shape the neural response in the auditory cortex. The current magnetoencephalography (MEG) experiment was designed to study the transient and sustained neuromagnetic correlates of prosodic contour information in vowels, with a particular focus on the P2 component. Twenty-four normal-hearing participants passively listened to vowel sequences in which both vowel type and prosodic contour were either unchanged or varied between successive vowels. At the level of single vowels, the results showed that falling contours elicit larger and earlier P2 responses than rising and flat prosodic contours. At the level of vowel triplets, the P2 was larger in response to stimulus sequences in which prosodic contour was varied across stimuli. The data indicate that the P2 might be a neural correlate of the early processing of prosodic contour information; moreover, they suggest that the P2 might be particularly sensitive to pitch glides, possibly due to longer time constants that are encompassed within the P2.