The Configuration of Hearing Loss Simulation Modulates Mismatch Responses and Discrimination to Mandarin Lexical Tone Contrasts.

Purpose: Objective measures of auditory capacity in the hearing loss population are crucial for cross-checking behavioral measures. Mismatch negativity (MMN) is an auditory event-related potential component indexing automatic change detection and reflecting speech discrimination performance. MMN can potentially serve as an objective measure of speech discrimination. This study examined whether the audibility of stimuli modulates MMN to Mandarin lexical tone contrasts by analyzing hearing loss simulation (HLS) in adults with normal hearing.

Method: The configurations of HLS were the between-subjects variable, with the sloping HLS simulating high-frequency hearing loss (more severe hearing loss at frequencies > 1000 Hz) and the rising HLS simulating low-frequency hearing loss. An AX discrimination task was used to measure the lexical tone discrimination by calculating '. A multideviant oddball paradigm with large (high-level vs. low-dipping tones, T1-T3) and small (high-rising vs. low-dipping tones, T2-T3) deviant contrasts was employed to examine whether deviant size affects MMN sensitivity to stimuli's audibility.

Results: The results showed that the T1-T3 change elicited MMN in the sloping and rising HLS groups. The T2-T3 change elicited MMN in the sloping HLS group but a positive mismatch response in the rising HLS group. Furthermore, regression analysis indicates that more negative mismatch responses to T2-T3 predict better performance in discriminating T2-T3 contrasts.

Conclusions: MMN to the T2-T3 change is sensitive to reduced audibility at frequencies lower than 1000 Hz. This suggests that MMN has the potential to serve as an objective assessment for evaluating lexical tone discrimination in people with hearing loss.