AN ACOUSTIC TEST FIXTURE FOR USE WITH HEARING PROTECTIVE DEVICES

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Authors
  1. Kunov, H.
  2. Abel, S.M.
  3. Giguere, C.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN);Toronto Univ, Toronto ONT (CAN) Inst of Biomedical Engineering
Abstract
As an alternative to psychoacoustical methods, an acousto-mechanical model of the hearing system was constructed to evaluate the acoustic attenuation provided by hearing protectors. The design is based on the KEMAR manikin and approximates the physical dimensions and the acoustical eardrum impedance of the median human adult. The model is composed of a torso unit, a head unit, two neck modules and three ear modules. The influence of the artificial skin, of the neck compliance and of the pinna on the attenuation of five earmuffs and five earplugs was investigated in a diffuse sound field. The effects are relatively small except for the mechanical properties of the intraaural skin which are found to affect greatly the attenuation of earplugs over a wide range of frequencies. The attenuation measurements were also compared to the subjective REAT method (ASA STD 1-1975). The agreement between the two methods is very satisfactory, especially when considering the relatively large standard deviations of the REAT method. In view of hearing protector assessment under impulse noise, a preliminary study was also undertaken in a free progressive sound field in order to evaluate hearing protectors in terms of both their amplitude and phase attenuation characteristics.
Date of publication
01 Oct 1986
Number of Pages
160
DSTKIM No
97-00622
CANDIS No
500889
Format(s):
Hardcopy;Document Image stored on Optical Disk

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