Analysis of audiometric notch as a noise-induced hearing loss phenotype in US youth: data from the National Health And Nutrition Examination Survey, 2005-2010.

OBJECTIVE Bilateral audiometric notch (BN) at 4000-6000 Hz was identified as a noise-induced hearing loss (NIHL) phenotype for genetic association analysis in college-aged musicians. This study analysed BN in a sample of US youth. DESIGN Prevalence of the BN within the study sample was determined and logistic-regression analyses were performed to identify audiologic and other demographic factors associated with BN. Computer-simulated "flat" audiograms were used to estimate potential influence of false-positive rates in estimating the prevalence of the BN. STUDY SAMPLE 2348 participants (12-19 years) following the inclusion criteria were selected from the National Health and Nutrition Examination Survey data (2005-2010). RESULTS The prevalence of BN was 16.6%. Almost 55.6% of the participants showed notch in at least one ear. Noise exposure, gender, ethnicity and age showed significant relationship with the BN. Computer simulation revealed that 5.5% of simulated participants with "flat" audiograms showed BN. CONCLUSION Association of noise exposure with BN suggests that it is a useful NIHL phenotype for genetic association analyses. However, further research is necessary to reduce false-positive rates in notch identification.