Digital music exposure reliably induces temporary threshold shift in normal-hearing human subjects.

OBJECTIVES: One of the challenges for evaluating new otoprotective agents for potential benefit in human populations is the availability of an established clinical paradigm with real-world relevance. These studies were explicitly designed to develop a real-world digital music exposure that reliably induces temporary threshold shift (TTS) in normal-hearing human subjects. DESIGN: Thirty-three subjects participated in studies that measured effects of digital music player use on hearing. Subjects selected either rock or pop music, which was then presented at 93 to 95 (n = 10), 98 to 100 (n = 11), or 100 to 102 (n = 12) dBA in-ear exposure level for a period of 4 hr. Audiograms and distortion product otoacoustic emissions (DPOAEs) were measured before and after music exposure. Postmusic tests were initiated 15 min, 1 hr 15 min, 2 hr 15 min, and 3 hr 15 min after the exposure ended. Additional tests were conducted the following day and 1 week later. RESULTS: Changes in thresholds after the lowest-level exposure were difficult to distinguish from test-retest variability; however, TTS was reliably detected after higher levels of sound exposure. Changes in audiometric thresholds had a "notch" configuration, with the largest changes observed at 4 kHz (mean = 6.3 ± 3.9 dB; range = 0-14 dB). Recovery was largely complete within the first 4 hr postexposure, and all subjects showed complete recovery of both thresholds and DPOAE measures when tested 1 week postexposure. CONCLUSIONS: These data provide insight into the variability of TTS induced by music-player use in a healthy, normal-hearing, young adult population, with music playlist, level, and duration carefully controlled. These data confirm the likelihood of temporary changes in auditory function after digital music-player use. Such data are essential for the development of a human clinical trial protocol that provides a highly powered design for evaluating novel therapeutics in human clinical trials. Care must be taken to fully inform potential subjects in future TTS studies, including protective agent evaluations, that some noise exposures have resulted in neural degeneration in animal models, even when both audiometric thresholds and DPOAE levels returned to pre-exposure values.

The effect of a hearing conservation program on adolescents' attitudes towards noise.

Crandell et al., reported that education programs such as hearing conservation programs (HCPs) represent the most common and well-recognized procedure in reducing the incidence of noise-induced hearing loss (NIHL). The purpose of this study was to assess the effectiveness of an HCP in changing knowledge and attitudes toward exposures to high intensity sounds or noise among adolescents aged 12-14 years. Local middle school students in physical education classes were recruited for participation. Sixty-four middle school students between the ages of 12 and 14 received pre- and post-test measures and participated in the HCP. The pre-test measure had 24 questions that included 5 demographic questions and 19 Likert-type questions [modified from the Youth Attitude to Noise Scale] that assess adolescents' attitudes towards noise; and a post-test measure included the identical 24 questions of the pre-test measure in addition to three subjective questions. A Wilcoxon signed rank test and a Two-Factor Analysis of Variance were completed to assess changes in knowledge and attitudes toward noise among the study population after receiving the HCP. A statistically significant reduction (P< 0.003) in pro-noise attitudes among the adolescents was present after the intervention. It was established that an HCP facilitated a change in pro-noise attitudes among adolescents. Further, the students thought this program facilitated learning of the auditory system and healthy hearing behaviors.