Assessment of mean auditory hazard incurred by occupational exposure to impulse noise

OBJECTIVES: To assess the collective hearing hazard entailed by occupational noise exposure. METHODS: The Late Audio-Sonometric Index (LASI) is a global score recommended for following up hearing loss in groups of workers exposed to traumatic noise, combining: daily noise exposure level (L(EX,8h) in dB(A)); individual hearing threshold level at 3kHz (HTL (3kHz) in dB); HTL(0)(3)(kHz) targeted at retirement; and 5 (or 10) years age bracket between 50 and 59 years of age. LASI=HTL(0)(3kHz) - HTL (3kHz)+10 log (age - 20) - 10 log (0.23×L(EX,8h) - 17.36). RESULTS: When L(EX,8h) exceeds 80dB(A) and HTL(0)(3kHz) is at 25dB, occasional audiometric surveillance may be recommended for workers exposed to hazardous impulse noise: e.g., should the median and the mean LASI values fall below 20 for men or 23 for women (indicative threshold values). CONCLUSION: This exponential model thus integrates the fact that daily exposure to impulse noise may be more harmful for hearing than eight hours exposure to continuous noise of equivalent energy. Language: en