Field study hearing protector evaluation procedure.
NIOSH 2001 Dec; :1-69
The Bone Conduction Loudness Balance (BCLB) method of measuring hearing protector attenuation was re-worked from earlier test versions and evaluated in a variety of situations, both laboratory and field. The procedure was implemented for running on any personal computer using the Windows operating system, and the protocol was simplified to emulate the standard hearing threshold test method. Laboratory testing using 26 previously inexperienced subjects showed that the revised procedure was easily implemented and more than twice as quickly done than the previous procedure, but was somewhat less consistent with the standard real ear attenuation at threshold (REAT) testing. Field hearing protection device (HPD) testing was evaluated with a total of 68 previously inexperienced subjects at four industrial sites. The mean time required for the BCLB test was about 6 minutes, and nearly all subjects were able to perform the test without difficulty, except for 2 of 68 who had too much hearing loss to hear the bone conduction reference sound at 200 Hz and one subject who was unwilling to learn the procedure. The primary difficulty was the tendency of some subjects to respond as in a threshold test, with re-instruction required for 17%. When used in a "candid" or unannounced test mode to evaluate HPD effectiveness as actually worn on the job, the procedure found attenuation values less than in a test setting, as was expected. The procedure was no more difficult to implement for candid testing than for other settings. The BCLB procedure was also used as part of an evaluation of the practicality and effect of using a HPD designed for better speech comprehension in noise (EAR UltraTech) with 21 hearing-impaired industrial subjects. Use of this HPD produced modest gains (mean improvement = 29%, p<0.01) in speech comprehension as measured by correct word identification on a 50-word test when compared with their normal HPD. However, 40% failed to wear the new HPD for extended testing due to discomfort and only 25% of those who did continue to wear it preferred it to their previous HPD.
Hearing-protection; Laboratory-testing; Hearing-tests; Hearing-loss; Ears; Ear-disorders
Final Grant Report
National Institute for Occupational Safety and Health
University of Arkansas, Department of Toxicology and Pharmacology, Little Rock, Arkansas