Alarming reports have been published about hearing loss in adolescents, and increasing leisure time noise exposure has been blamed. If the exposure limits from the Noise at Work Regulations are applied, discotheque music as well as music from portable music players are associated with the risk of hearing loss. The empirical evidence for this association, however, is not sufficient. Not even an increase in the prevalence of noise-induced hearing loss among adolescents can be documented. OHRKAN is a prospective cohort study aimed to produce information on the prevalence of hearing loss as well as its risk factors in adolescents. Currently, a total of 2,240 pupils in grade 9 at schools in the city of Regensburg, Germany, have been recruited. Data on noise exposure were collected using standardized questionnaires. In addition, hearing status was assessed by medical examination including tympanometry, audiometry, and distortion-product otoacoustic emissions. Developments in noise exposure as well as hearing status will be assessed in follow-up data collections. Independent of this empirical assessment preventive measures are already needed now to reduce the risk of hearing loss in adolescents and young adults.