Brainstem and early cortical auditory activities associated with language differences in acoustic cue weighting for voicing perception

The purpose of the present study was to identify neural activities reflecting language differences in acoustic cue weighting for phonetic perception. We examined whether brainstem and early cortical auditory responses to voice-onset time (VOT) and onset frequency of fundamental frequency (onset F0) were different between two groups of listeners, native Japanese speakers and Korean second-language learners of Japanese, who use a VOT and onset F0, respectively, as the primary perceptual cue for voicing. In the experiment, we measured auditory brainstem responses (ABRs) and cortical N1 response of the Japanese and Korean participants while listening to stop-consonant stimuli varying in VOT and onset F0 (10 ms and 80 Hz, 30 ms and 80 Hz, or 30 ms and 120 Hz). We found that the N1 response was much more sensitive to VOT distinction in the Japanese than Korean participants, although the distinction of onset F0 was not reflected in early cortical responses in either language groups. There was no obvious difference in the ABRs between the Japanese and Korean participants. These results suggest that early cortical auditory activity is related to the processing of acoustic cue weighting for phonetic perception, while brainstem auditory activity is stimulus-dependent.