An investigation of prototypical and atypical within-category vowels and non-speech analogues on cortical auditory evoked related potentials (AERPs) in 9 year old children

The present study examined cortical auditory evoked related potentials (AERPs) for the P1–N250 and MMN components in children 9 years of age. The first goal was to investigate whether AERPs respond differentially to vowels and complex tones, and the second goal was to explore how prototypical language formant structures might be reflected in these early auditory processing stages. Stimuli were two synthetic within-category vowels (/y/), one of which was preferred by adult German listeners (“prototypical-vowel”), and analogous complex tones. P1 strongly distinguished vowels from tones, revealing larger amplitudes for the more difficult to discriminate but phonetically richer vowel stimuli. Prototypical language phoneme status did not reliably affect AERPs; however P1 amplitudes elicited by the prototypical-vowel correlated robustly with the ability to correctly identify two prototypical-vowels presented in succession as “same” (r = −0.70) and word reading fluency (r = −0.63). These negative correlations suggest that smaller P1 amplitudes elicited by the prototypical-vowel predict enhanced accuracy when judging prototypical-vowel “sameness” and increased word reading speed. N250 and MMN did not differentiate between vowels and tones and showed no correlations to behavioural measures.

Research Highlights
► Enhanced auditory P1 amplitude distinguishes vowels from complex tones in healthy 9 year old children.
► P1 amplitudes elicited by a prototypical-vowel correlate with prototype discrimination (r = −0.70) and word reading fluency (r = −0.63): smaller P1 amplitudes are related to enhanced accuracy when judging prototypical-vowel “sameness” and increased word reading speed.
► N250 and MMN did not differentiate between vowels and tones and showed no correlations to behavioural measures.