Monitoring of noise-induced hearing threshold shifts among adolescents: The relevance of exposure to leisure noise in the prospective Ohrkan cohort study

Introduction: Exposure to high continuous noise during leisure activities such as attending discotheques or listening to portable listening devices at high volume levels is presumed to have harmful effects on the hearing system of young adolescents. Therefore, the follow-up study Ohrkan funded by the Bavarian State Ministry for the Environment and Health was initiated to track its members over a 10 years period. Currently, the 5-year follow-up is ongoing. Objectives: Analysis of the association of hearing threshold shifts and total leisure noise exposure over five years. Methods: A total of 2,149 students of grade 9 (mostly aged 15-16 years) in the City of Regensburg were recruited from 2009-2011. In the baseline survey and in the recent survey five years later exposure to leisure noise was assessed by self-administered questionnaire and audiometric examinations were performed at the university hospital of Regensburg. The self-reported frequency of participation in noisy activities was combined with literature-based values of usual sound pressure levels of these activities to calculate the total leisure noise exposure. Two different outcomes were defined: a noise notch with a distinct audiometric pattern as well as the maximum threshold shift of both ears at 3, 4, 6 kHz. A longitudinal analysis of these data by generalized linear models (GLM) is in progress to determine the long-term effects of total leisure noise exposure. Results: Up to now, data from over 1,000 students are available. The study methods including the statistical model as well as the latest results using 5-year follow-up data will be presented. Conclusions: Results will be discussed with respect to the burden of leisure noise exposure and the association with the hearing ability of adolescents. Potential implications for the development of early prevention programs and for regulatory measures to reduce leisure noise exposure will be suggested.