Impaired speech-in-noise perception in individuals with a history of hearing symptoms after noise exposure

Prior work shows that individuals who frequently experience symptoms following noise exposure have greater hearing complaints and worse tone-in-noise detection abilities even with "normal" audiometric thresholds. This study extends previous work by quantifying the impact of post-exposure hearing symptoms on speech-in-noise (SIN) detection. Intelligibility and response times were examined in two large samples of U.S. service members (SMs) who completed tablet-based questionnaires, pure-tone audiometry, and SIN tests based on the Modified Rhyme Test (MRT). In Experiment 1, 1551 SMs completed a version of the MRT based on the clinical MRT80. In Experiment 2, 4768 SMs completed an abbreviated MRT without carrier phrases. Participants were categorized based on hearing acuity and questionnaire responses. Mixed-effects models predicted MRT outcomes using better-ear four-frequency pure-tone average (PTA4), post-exposure hearing symptom history, and noise exposure as predictors. Both experiments showed effects of post-exposure symptom history and PTA4 on accuracy and response time. Overall, SMs with a history of post-exposure hearing symptoms exhibited deficits in SIN performance, even with normal audiometric thresholds. These findings suggest that symptoms consistent with temporary threshold shifts (TTS) may indicate underlying auditory damage, underscoring the importance of considering TTS in hearing conservation, clinical assessment, and research.