Poster #73 - The neural development of auditory temporal modulation processing for phonetic perception in the first year of life

• In Event: Poster Session 01

Abstract

Before 10 months of age, infants are not yet attuned to the consonants of their native language, meaning that, compared to adults, they are sensitive to certain non-native phonological contrasts. The nature of the mechanisms shaped by age and exposure to the native language is yet to be discovered. The current project hypothesizes that auditory mechanisms supporting speech perception may play a crucial role in perceptual attunement. The project explores the interaction between auditory and speech perception abilities during early development by looking at the neural correlates underlying the processing of specific speech acoustic cues.
This study adopts a psychoacoustic approach suggesting that the auditory system selectively decomposes the spectral and temporal modulations of speech. Such acoustic modulations can be artificially manipulated using vocoders to assess their role in speech perception. To explore the neural underpinnings of the processing of temporal modulations, and particularly of amplitude and frequency modulations (AM/FM), we used electroencephalography (EEG) to measure the cortical auditory evoked potentials (CAEPs) for native and non-native consonants in French-learning 6-month-old (N=21), 10-month-old (N=20) and French adult listeners (N=21). We used vocoders to process three syllables: French-voiced /aba/, French-unvoiced-unaspirated /apa/, and an English-unvoiced-aspirated /apha/. Three vocoder conditions were designed to preserve: i) original FM and AM, ii) original AM only, and iii) the slowest AM (< 8 Hz) only.
Overall, our results show that all groups show different CAEPs between the original sounds and their FM degraded versions, but that further degradation of faster AM cues did not further affect CAEPs. When looking at individual syllables, 10-month-old response patterns are more aligned with adult’s, suggesting that neural processing of temporal modulations may already be adult-like at 10-months of age.

Authors

• Monica Hegde, Université de Paris (Integrative Neuroscience and Cognitive Center-INCC)
  Presenting Author

• Laurianne Cabrera, Centre National de la Recherche Scientifique (CNRS)