Time-frequency characteristics of contralateral suppression of transient evoked otoacoustic emissions in auditory neuropathy spectrum disorder

Background: The present study aimed to investigate the functioning of the efferent system in individuals with auditory neuropathy spectrum disorder (ANSD) using contralateral suppression of transient evoked otoacoustic emission (TEOAE). Methods: TEOAE was analyzed to understand changes in amplitude and latency using wavelet-based time-frequency analysis. TEOAEs were measured in 20 individuals with normal hearing (NH) and 20 individuals with ANSD, aged 15–45 years, under two conditions: with and without broadband noise in the contralateral ear. Results: In NH, TEOAE amplitude was significantly reduced up to 3 kHz with contralateral noise, but no suppression was observed in the ANSD group. Contralateral noise had a negligible effect on TEOAE latency in both groups. Conclusion: The absence of latency shifts but affected TEOAE suppression amplitude in ANSD suggests that while the timing of neural transmission is intact, the strength or effectiveness of efferent suppression is compromised in ANSD individuals.