Occupational noise exposure, hearing loss, and notched audiograms in the HUNT Nord‐Trøndelag hearing loss study, 1996–1998

OBJECTIVES/HYPOTHESIS To study the prevalence and usefulness of audiometric notches in the diagnosis of noise-induced hearing loss (NIHL). STUDY DESIGN Audiograms and data on noise exposure from 23,297 men and 26,477 women, aged 20 to 101 years, from the Nord-Trøndelag Hearing Loss Study, 1996-1998. METHODS The prevalence of four types of audiometric notches (Coles, Hoffman, Wilson) and 4 kHz notch were computed in relation to occupational noise exposure, age, sex, and report of recurrent ear infections. RESULTS The prevalence of notches in the 3 to 6 kHz range (Wilson, Hoffman, and Coles) ranged from 50% to 60% in subjects without occupational noise exposure, and 60% to 70% in the most occupationally noise-exposed men. The differences were statistically significant only for bilateral notches. For 4 kHz notches, the prevalence varied from 25% in occupationally nonexposed to 35% in the most occupationally exposed men, and the differences were statistically significant for both bilateral and unilateral notches. For women, the prevalence of notches was lower than in men, especially for 4 kHz notches, and the differences between occupationally noise exposed and nonexposed were smaller. Recreational exposure to high music was not associated with notched audiograms. CONCLUSIONS The detection of bilateral notches and unilateral 4 kHz notches is of some value in diagnosing NIHL, especially in men. LEVEL OF EVIDENCE 4 Laryngoscope, 127:1442-1450, 2017.