title: Neoprene wet-suit hood affects low-frequency underwater hearing thresholds.
abstract: BACKGROUND
  Psychophysical measures of wet-suit hood sound attenuation are needed to provide the diving community with guidance on protection from underwater sound.
  
  
  METHODS
  Underwater hearing thresholds were obtained from 15 male and 5 female recreational divers with and without a 3-mm thick wet-suit hood. Dives were conducted at a depth of 1 m in a large quiet anechoic pool. Thresholds were determined using a two-interval forced-choice procedure with a 0.71 probability of positive response at convergence. A 1-s pure tone was presented with a 20-ms rise and fall time at 100, 200, 250, 300, 400, and 500 Hz.
  
  
  RESULTS
  Without a wet-suit hood, mean thresholds decreased from 99 dB re 1 microPa at 100 Hz to 85 dB at 500 Hz. Thresholds were statistically similar at 100 to 300 Hz with and without the wet-suit hood, but were significantly increased at 400 and 500 Hz with the hood (p < 0.001).
  
  
  CONCLUSIONS
  In conclusion, at shallow depths, a 3-mm neoprene wet-suit hood attenuates underwater sound by approximately 10 dB for frequencies between 400 Hz and 500 Hz. At frequencies below 400 Hz, a 3-mm neoprene wet-suit hood offers no sound protection.
authors.affiliation: Naval Submarine Medical Research Laboratory, Box 900, Groton, CT 06349-5900, USA. fothergill@nsmrl.navy.mil
authors.forename: David M
authors.initials: DM
authors.lastname: Fothergill
authors.forename: John R
authors.initials: JR
authors.lastname: Sims
authors.forename: Michael D
authors.initials: MD
authors.lastname: Curley
mesh_terms: D000328:Adult; D001309:Auditory Threshold; D004242:Diving; D005260:Female; D006260:Head Protective Devices; D006320:Hearing Tests; D006801:Humans; D008297:Male; D008891:Military Science; D009387:Neoprene
chemical_list: D009387:Neoprene