Psychophysical Measurements of a Neoprene Wetsuit Hoods Sound Attenuation as a Function of Dive Depth and Frequency: Hyperbaric Chamber Trials
Technical Report,01 Oct 1999,30 Sep 2001
NAVAL SUBMARINE MEDICAL RESEARCH LAB GROTON CT GROTON United States
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Underwater hearing thresholds were collected from 13 U.S. Navy trained divers while bare headed and while wearing a 7 mm neoprene wetsuit hood. Testing frequencies and depths ranged from 100 Hz to 12,000 Hz and from near surface to 132 feet of sea water fsw, respectively. All dives were conducted in a small immersion tank in NSMRLs hyperbaric chamber. Wetsuit hood attenuation was calculated from the difference between hooded and unhooded hearing thresholds. The attenuation of underwater sound provided by a 7 mm neoprene wetsuit hood at the threshold of hearing was measured as being from 0 dB to approximately 34 dB. The amount of attenuation is dependent on at least two factors, frequency of the sound and ambient pressure simulating depth. In general, the lower frequency sounds are attenuated less and the higher frequency sounds are attenuated more when a neoprene wetsuit hood is worn. The greatest attenuation 20-34 dB was above 4000 Hz and almost no attenuation was measured at 100 and 250 Hz. From 500 to 1000 Hz the amount of sound attenuation decreased as the ambient pressure increased.
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