Occupational hearing loss. The significance of asymmetrical hearing thresholds.
In 1873 consecutive patients referred for compensation assessment for presumed industrial hearing loss, 281 (15%) had an average difference in hearing threshold between the ears of 15 dB at 1/2, 1, 2 and 4 kHz. An unrelated cause was found in 115 (6%). It was due to trauma in 37 (2%), unexplained in 32 (1.7%) and attributed to noise exposure in 97 (5.2%). The possible mechanisms for noise as a cause are discussed and include shielding of one ear from noise, unequal recovery after severe noise exposure, and unequal sensitivity of the ears. After extensive investigation, including X-rays, vestibular tests and some myelograms, no treatable disorder was discovered.
D001299:Audiometry; D006314:Hearing Loss, Conductive / Q000175:diagnosis / Q000209:etiology; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis* / Q000209:etiology; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000209:etiology; D006320:Hearing Tests; D006801:Humans; D009784:Occupational Diseases / Q000175:diagnosis* / Q000209:etiology