Annals of Occupational and Environmental Medicine

Original Article

Hearing Thresholds in Electronics Sound Inspectors Exposed to Continuous and Impulsive Type Noises: Seong Ah Kim, Kyoo Sang Kim; Korean Journal of Occupational and Environmental Medicine 2004;16(3):227-235. Published online September 30, 2004; DOI: https://doi.org/10.35371/kjoem.2004.16.3.227

Abstract PDF: OBJECTIVES
To investigate the relation between different types of exposure to noise and a classic sign of noise-induced hearing loss (NIHL); the audiometric notch.
METHODS
A cross-sectional epidemiological survey was carried out in electronics sound inspectors exposed to continuous and impulsive type noises. The noise levels in the working environments, and the audiometric hearing threshold levels were measured.
RESULTS
Electronics sound inspectors were exposed to impulsive noise ranging from 74.1 to 88.9 dBA. The hearing loss induced by impulsive noise was greater and was characterized by maximum loss at 6 kHz audiometric frequency, as opposed to the notch at 4 kHz that is typical of continuous noise.
CONCLUSIONS
The results suggest that the probable effect of impulsive noise on hearing should be considered even when the exposure is within the 85 dB equivalent A-weighted level. To diagnose NIHL it is important to elicit a detailed and accurate history of exposure to noise. Although the notch at 4 kHz is a well established clinical sign and may be valuable in confirming the diagnosis, the 6 kHz notch is variable and of limited importance.

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