Neural Correlates of Speech Segregation Based on Formant Frequencies of Adjacent Vowels

Document Type

Article

Publication Date

1-1-2017

Publication Title

Scientific Reports

Volume

7

Abstract

The neural substrates by which speech sounds are perceptually segregated into distinct streams are poorly understood. Here, we recorded high-density scalp event-related potentials (ERPs) while participants were presented with a cyclic pattern of three vowel sounds (/ee/-/ae/-/ee/). Each trial consisted of an adaptation sequence, which could have either a small, intermediate, or large difference in first formant (I "f 1) as well as a test sequence, in which I "f 1 was always intermediate. For the adaptation sequence, participants tended to hear two streams ("streaming") when I "f 1 was intermediate or large compared to when it was small. For the test sequence, in which I "f 1 was always intermediate, the pattern was usually reversed, with participants hearing a single stream with increasing I "f 1 in the adaptation sequences. During the adaptation sequence, I "f 1-related brain activity was found between 100-250 ms after the /ae/ vowel over fronto-central and left temporal areas, consistent with generation in auditory cortex. For the test sequence, prior stimulus modulated ERP amplitude between 20-150 ms over left fronto-central scalp region. Our results demonstrate that the proximity of formants between adjacent vowels is an important factor in the perceptual organization of speech, and reveal a widely distributed neural network supporting perceptual grouping of speech sounds. © The Author(s) 2017.

Language

english

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