[abstract] THE EFFECT OF DEPTH ON UNDERWATER SOUND ATTENUATION OF A NEOPRENE WETSUIT HOOD: HYPERBARIC CHAMBER TRIALS

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[abstract] THE EFFECT OF DEPTH ON UNDERWATER SOUND ATTENUATION OF A NEOPRENE WETSUIT HOOD: HYPERBARIC CHAMBER TRIALS

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Title: [abstract] THE EFFECT OF DEPTH ON UNDERWATER SOUND ATTENUATION OF A NEOPRENE WETSUIT HOOD: HYPERBARIC CHAMBER TRIALS
Author: Fothergill, DM; Cudahy, EA; Schwaller, D
Abstract: BACKGROUND: Physical measures of underwater sound attenuation due to wetsuit hoods suggest that attenuation is decreased as depth increases. The goal of this study was to establish the effect of depth on psychophysical measures of wetsuit hood sound attenuation. METHODS: Experiments were conducted in a non-parallel walled water tank located in a hyperbaric chamber with the head of the diver 18-inches below the water surface. Thirteen US Navy divers performed underwater hearing threshold tests at 10 frequencies from 100 - 12,000 Hz while bareheaded and while wearing a 7-mm neoprene wetsuit hood at depths of: 3, 132, 66, 33, and 10 fsw. Wetsuit hood sound attenuation was determined from the dB difference between the hooded and unhooded underwater hearing thresholds. RESULTS: Repeated measures ANOVA revealed significant main effects for depth (p less than 0.00001), frequency (p less than 0.00001) and a significant two-way interaction between depth and frequency (p less than 0.00001) on wetsuit hood sound attenuation. Tukey's HSD post hoc analysis showed significant decreases in wetsuit hood sound attenuation with increasing depth only for frequencies from 500 to 1500 Hz (p less than 0.05). For frequencies below 500 Hz there was virtually no sound attenuation. Above 1,500 Hz, where the mean attenuation was between 20 and 30 dB, there was no significant effect of depth on wetsuit hood sound attenuation. CONCLUSIONS: Decreases in wetsuit hood sound attenuation with increasing depth appear only to occur at frequencies between 500 and 1500 Hz. This has important implications for setting guidance for underwater sound exposures since this frequency region encompasses the most sensitive region for underwater hearing. It is recommended that open water tests be conducted to verify the current findings to determine their applicability under conditions where the characteristics of the sound field are not affected by the constraints of a small tank.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/1515
Date: 2004

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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