Efferent inhibition of SSOAEs and TEOAEs in individuals with ANSD Using conventional and Time-Frequency Analysis

Abstract

Auditory Neuropathy Spectrum Disorder (ANSD) involves difficulties in speech comprehension, abnormal auditory brainstem responses, and intact pure-tone detection thresholds. This dissertation investigates cochlear and efferent functioning in ANSD using time-frequency analyses of otoacoustic emissions (OAEs). It compares conventional and advanced time-frequency measures, such as wavelet transform and root mean square (RMS) analyses, to evaluate their diagnostic utility. The study examines spontaneous and transient evoked otoacoustic emissions (SSOAEs and TEOAEs) under quiet and noisy conditions, comparing peak amplitude, frequency, wavelet amplitude, and latency measures between individuals with and without ANSD. The findings revealed significant differences in both conventional and time-frequency measures of OAEs between ANSD and control groups. Enhanced amplitude and altered latency in TEOAEs, along with reduced suppression of SSOAEs under contralateral noise, indicate compromised efferent auditory function in ANSD. However, limited change in frequency and latency changes with contralateral noise suggest that neural firing timing might not be affected in ANSD. These results highlight the potential of time-frequency analysis for early detection and characterization of auditory deficits in ANSD. This dissertation provides a comprehensive analysis of OAEs using advanced signal processing techniques, emphasizing the importance of temporal and phase analyses in understanding ANSD's pathophysiology, and paving the way for improved diagnostic and management strategies.