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Syed M. Ahmed

and Tar-Ching Aw


July 30, 2015: This chapter has been re-evaluated and remains up-to-date. No changes have been necessary.

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date: 19 September 2021

For clinical purposes, noise is measured in decibels weighted according to the sensitivity of the human ear (dB(A)). Regardless of source, the effects of overexposure to noise are similar. Initially there is a temporary threshold shift, where reversibility of hearing loss is possible with removal away from further noise. Permanent threshold shift occurs following prolonged and/or intense exposure, with poor prospects for improvement of hearing. The classical audiogram for noise-induced hearing loss shows a 4 kHz dip. Prevention is by reducing exposure to noise at source, and in the United Kingdom a limit for exposure has been set at 87 dB(A) averaged over an 8-h day or 140 dB(A) for any instantaneous impulse noise....

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