Evaluation of individuals with known or suspected noise damage to hearing

Abstract

The diagnosis of hearing impairment due to noise damage is based on the assessment of the type and level of exposure to noise, the patient's medical history, and a clinical and audiometric evaluation. The risk for developing hearing loss increases substantially when the equivalent sound pressure levels of noise exceed 80dB(A). Very high exposures (above 100dB(A)), usually to impulse noise (e.g. fireworks), can result in acoustic trauma. In this case, sensorineural hearing loss develops immediately after exposure and is frequently accompanied by tinnitus. It can be unilateral or asymmetrical, and temporary (temporary threshold shift – TTS) or permanent (permanent threshold shift – PTS). Noise-induced hearing loss (NIHL) that develops after prolonged occupational exposures to relatively moderate levels of noise (85–100dB(A)) is a bilateral, symmetrical, or almost symmetrical, and permanent sensorineural hearing loss progressing slowly over the years of employment. The most dynamic rise in PTS can be seen du...