A cross-linguistic examination of cortical auditory evoked potentials for a categorical voicing contrast

Abstract

Behavioral perceptions and cortical auditory evoked potentials (CAEPs) from native English ( N = 10) and Spanish speakers ( N = 10) were recorded for speech stimuli that constitute phonetically relevant categories of voicing. The stimuli were synthesized bilabial stop consonant-vowel syllables in a continuum ranging from/ba/to/pa/that varied in voice onset time (VOT) from 0 to 60 ms. Different behavioral perceptions were evidenced by significantly different categorical phonetic boundaries between the two groups ( p < .0001). In contrast, there were no significant differences in CAEP component P1, N1, and P2 mean latencies or P1–N1 and N1–P2 amplitudes between groups ( p > .05). Peak P1, N1, and P2 response latencies and P1–N1 and N1–P2 amplitudes increased significantly with increasing VOTs ( p < .0001 and p < .001, respectively). There were no systematic changes in CAEP morphology that corresponded to listeners’ perceptual categorical boundaries. These findings are consistent with the notion that changes in morphology of the P1–N1–P2 response are related to acoustical changes in speech sounds and are independent of phonetic categorization of voicing cues across language groups.