Effects of Manipulating the Amplitude of Consonant Noise Portion on Subcortical Representation of Voice Onset Time and Voicing Perception in Stop Consonants

Purpose The purpose of this study was to investigate whether speech perception would reflect small latency changes in subcortical speech representation. Method Twelve native Japanese listeners participated in the experiment. Those listeners participated in speech identification task and auditory brainstem response (ABR) measurement using /d/–/t/ continuum stimuli varying in voice onset time (VOT) with manipulation of the amplitude of initial noise (consonant) portion, the duration of which corresponded to VOT. Results Increasing the noise portion amplitude lengthened subcortical representation of VOT, which is the latency difference between ABRs synchronizing to the onsets of initial noise and following periodic (vowel) portions (VOTABR) and made listeners likely to perceive the stimuli with ambiguous VOT as a voiceless stop /t/. In addition, the amount of VOTABR lengthening was close to that of the VOT boundary shortening. Conclusion A few milliseconds of difference in subcortical speech representation a...