Noise Exposure History and Age-Related Changes to Hearing

Importance: Noise exposure is a major modifiable risk factor for hearing loss, yet it is not known whether it affects the rate of hearing decline in aging. Objective: To determine the association of noise exposure history with the rate of pure-tone threshold change per year. Design, Setting, and Participants: This longitudinal cohort study was conducted in the ongoing community-based Medical University of South Carolina Longitudinal Cohort Study of Age-Related Hearing Loss (1988 to present with the sample based in Charleston, South Carolina, and surrounding area). Following a comprehensive baseline examination, participants attended annual examinations, during which audiometric data were collected. Participants with audiometric data from at least 2 examinations and noise exposure history data were included in the study. Data were analyzed between September 2023 and July 2024. Exposure: Noise exposure history, determined by a self-reported questionnaire and history of military service, was categorized as no/little, some, or high exposure. Main Outcomes and Measures: Outcome measures were individual audiometric thresholds (0.25 kHz to 8.0 kHz) and pure-tone average (PTA) of thresholds at frequencies 0.5 kHz, 1.0 kHz, 2.0 kHz, and 4.0 kHz, averaged bilaterally. Linear mixed regression models were used to estimate the association of age (per every 1 additional year) with the rate of threshold change at each frequency and PTA, for each noise exposure category. The association of noise exposure with the rate of annual threshold change was determined by an interaction term of age (longitudinal time variable) and noise exposure in regression models. Results: Of 1347 participants, the mean (SD) baseline age was 63 (14) years, and 772 (57%) were female. The mean (SD) follow-up time was 5.1 (5.7) years. Compared to the no/little noise exposure group, groups with some and high noise exposure had significantly higher baseline thresholds from 2.0 kHz to 8.0 kHz and PTA, and 1.0 kHz to 8.0 kHz and PTA, respectively. Those with high noise exposure (vs no/little) showed higher rates of threshold change per year at 1.0 kHz and 2.0 kHz. Participants with some and high noise exposure showed lower rates of change per year at 3.0 kHz to 8.0 kHz and 4.0 kHz to 8.0 kHz, respectively, where hearing loss had already occurred. The rate of PTA change per year did not differ across noise exposure groups. Conclusions and Relevance: In this cohort study, noise exposure was associated with poorer baseline hearing and higher rates of annual decline at some midfrequencies. Noise exposure can have immediate and potentially long-term negative impacts on hearing.