NIOSHTIC-2 Publications Search

A controlled investigation of in-field attenuation performance of selected insert, earmuff, and canal cap hearing protectors.

Park Y; Casali JG
Hum Factors 1991 Dec; 33(6):693-714
A study of the effect of fit training on the attenuation of hearing protectors was conducted. The study group consisted of 40 male industrial workers, mean age 37.9 years. They underwent audiometric testing on two occasions while wearing one of four types of hearing protectors, an E-A-R foam earplug, an Ultrafit earplug, a Bilsom earmuff, and a Willson ear canal cap, in their workplace for 3 weeks. The workplaces were characterized by time weighted average noise exposures of 86.5 to 106.4 decibels-A. In the first round of tests, the subjects fit the protectors themselves after reading the manufacturers' package instructions (subject fit). In the second round of tests the subjects were instructed on the proper method of fitting by one of the experimenters (trained fit). In both rounds of tests, the subjects were taken from their workplace to the testing site without prior knowledge of when they were to be tested. They were not permitted to readjust the fit of the protectors before testing. The audiometric test consisted of determining hearing thresholds over the frequency range of 125 to 8000 hertz. The data for the earplugs and earmuff were compared with data obtained in a previous laboratory simulation study. Noise attenuation obtained with the two earplugs was significantly improved after the subjects were instructed on how to fit the plugs compared to when they fit themselves. Attenuation values obtained with the earmuff and ear canal cap did not differ significantly between the subject fit and trained fit condition. Attentuation values obtained with the two earplugs were significantly lower than those measured in the laboratory for both fit conditions. Attenuation obtained with the earmuff did not differ significantly from that obtained in the laboratory. The authors conclude that noise attenuation obtained with earplugs is significantly improved when workers are trained in their use. Training does not appear to affect the ability of earmuffs and ear canal caps to attenuate noise. Laboratory testing of earplugs does not yield reliable estimates of protection under actual field conditions.
NIOSH-Publication; NIOSH-Grant; Noise-induced-hearing-loss; Hearing-protection; Psychophysiology; Ear-protectors; Laboratory-testing; Noise-exposure; Occupational-exposure; Audiometry; Safety-education
Indus Engr and Operations Res Virginia Polytechnic Institute Blacksburg, VA Blacksburg, VA 24061
Publication Date
Document Type
Journal Article
Funding Amount
Funding Type
Fiscal Year
Identifying No.
Issue of Publication
Priority Area
Source Name
Human Factors
Performing Organization
Virginia Polytechnic Inst and St Univ, Blacksburg, Virginia
Page last reviewed: September 22, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division