Speech-ABR Representations and Non-lateralization Effect for the Stimulation Intensity / 听力学及言语疾病杂志

ABSTRACT

Objective To investigate the effects of stimulation intensity on subcortical auditory processing of speech and assess the subcortical asymmetry of speech elements at the brainstem level using speech evoked auditory brainstem response (s-ABR) ,so as to provide more clues for the mechanism of speech cognitive behaviors .Meth‐ods Speech syllables /da/with three intensities(40 dB HL ,60 dB HL and 80 dB HL) were presented monaurally to 29 normal hearing adults ,and corresponding s-ABRs were recorded .The stimulus and response parameters ,inclu‐ding latency and amplitude in time domain ,fundamental frequency and formants in frequency domain were analyzed statistically .Results With the increase of stimulation intensity ,significant shorter latency and larger amplitude were observed for the feature peaks of s-ABR (P<0 .05) .The latency changes corresponding to the same intensity increment were at variance with the periodic components and the transient components .The fundamental frequency and formants of the stimulus syllables that extracted preferably from s - ABRs were encoded less vigorously in ascending order which was the same as that for the intensity .The responses to the right and left monaural stimula‐tion resembled without significant lateralized difference .Conclusion The s -ABR is able to encode faithfully the speech sound in terms of timing and spectrum components with high correspondence with the stimulus intensity .The different latency characteristics of periodic components and transient responses may imply more underlying coding information of speech sound .However ,lateral asymmetry speech processing is not considerable at the brainstem level .