Broadband Noise Acoustic Stapedial Reflex Thresholds as a Marker of Cochlear and Neural Integrity in Individuals with Normal Audiograms

Abstract

Background/Objectives: Some individuals present with difficulty understanding speech in noise, tinnitus, or both, despite normal conventional audiometric hearing thresholds. This study evaluated whether acoustic stapedial reflex thresholds (ASRTs) could serve as a clinically useful indicator of auditory complaints not captured by conventional audiometry. Methods: ASRTs for pure tones and broadband noise (BBN) were measured in 146 ears (73 participants) from controls, music students, and symptomatic participants. Bayesian random-intercept linear regression models were used to compare ASRTs among groups, adjusting for age and sex. ASRT difference scores were also used for ROC analysis and to estimate the difference between pure-tone and BBN thresholds (“BBN advantage”). Results: Symptomatic ears showed higher ASRTs than control ears with BBN stimuli, after adjustment for age and sex. Symptomatic ears had a lower AvgDiff posterior mean (reduced BBN advantage) than control ears. ASRTs for music students were directionally consistent with an intermediate pattern, but with wider credible intervals and greater uncertainty. Exploratory ROC analysis showed moderate separation between symptomatic and non-symptomatic ears with AvgDiff; however, symptom status was not independently validated against any diagnostic reference standard. Conclusions: The study suggests that a reduced BBN advantage may be associated with auditory complaints in individuals with normal hearing at conventional audiometric frequencies. However, these findings should be interpreted with caution and not used for specific diagnostic purposes, as the symptomatic group was substantially older and symptom status was not independently validated against any diagnostic reference standard.