Sound localization with an army helmet worn in combination with an in-ear advanced communications system


  1. Abel, S.M.
  2. Boyne, S.
  3. Roesler-Mulroney, H.
Corporate Authors
Defence R&D Canada - Toronto, Toronto ONT (CAN)
The effect on horizontal plane sound source identification of a Kevlar army helmet worn alone or in combination with a Nacre QUIETPRO® in-ear communications system was investigated. Ten normal-hearing male subjects participated in eight experimental conditions defined by four variations of the helmet (head bare, and helmet worn with the pinnae uncovered, partially covered and fully covered) and two levels of ear occlusion (unoccluded and occluded). Accuracy in judging direction was assessed using a horizontal array of eight loudspeakers surrounding the subject at a distance of 1 m. The stimulus was a 75-dB SPL, 300-ms broadband white noise. Outcome was significantly determined by both degree of pinnae coverage and ear occlusion. With the ears unoccluded, overall percent correct ranged from 93.6% (bareheaded) to 79.7% (full pinnae coverage), compared with 83.4%-77.5% with ear occlusion. Both variables affected the confusion of mirror image positions 30 degrees apart in front and back of the interaural axis. With ear occlusion, front when given back errors were more likely than back when given front, increasing with degree of pinnae coverage to 49% and 25.4%, respectively, averaged across right and left sides. With the ears unoccluded, the likelihood of the two types of error was similar except for full pinnae coverage where front when given back errors were less likely, 29% vs 41.7%. The outcomes suggest that, except for these positions, neither the helmet nor the communicati

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directional hearing, sound source identification, front/back confusions
Report Number
DRDC-TORONTO-SL-2008-192 — Scientific Literature
Date of publication
31 Dec 2009
Number of Pages
Electronic Document(PDF)

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