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Military aviation noise:noise-induced hearing impairment and noise protectionKuronen, P. (Pentti) 03 September 2004 (has links)
Abstract
This research on military aviation noise was conducted because the
personnel working with military aircraft were concerned about noise
induced hearing damage. In addition, comprehensive data on hearing
impairments and occupational exposure of military pilots in the Finnish
Air Force was not available. Moreover, data on the effects of overflight
noise of military jets was necessary for the evaluation of noise induced
hearing deteriorations of members of the public who might be exposured
accidentally for the low-level jets' overflights.
The averaged noise exposure levels of pilots varied during a
flight from 97 dB(A) to 106 dB(A) in the cockpit and from 83 dB(A) to
100 dB(A) at the entrance of the ear canal. Radio noise was 4–10
dB higher than background noise inside the helmet. The attenuation
provided by air crew helmets varied from10 to 21 dB(A) in the
laboratory, and was at the same level during real flights. The
attenuation measured in the laboratory and in working conditions was
about 30 dB(A) for earmuffs. An active noise cancellation (ANC) device
decreased averaged noise exposure (LAeq8min)
4–8
dB over the noise attenuation of the same helmets when the ANC system
was off.
The noise of overflights by military jets were measured and the
noise levels were lower than those known to cause the permanent
threshold shifts. However, noise induced hearing damages might be
possible in certain conditions.
In order to assess the hearing loss risk of pilots, hearing
thresholds were measured before and after one flight using both
conventional and extended high frequency (EHF) audiometry. Minor
temporary threshold shifts (TTS) were revealed. The risk of
noise-induced damage at the studied exposure levels is, in all
probability, rather small.
A novel NoiseScan data management system proved to be an
interesting tool in assessment of the risk of developing hearing
impairment on the basis of known risk factors. Due to the small number
of risk factors, the hearing of pilots was shown to be at considerably
less risk than that of industrial workers in Finland.
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