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Development of a Laboratory Procedure for Estimation of the Field Performance of Hearing Protectors.

NIOSH 1992 Apr:41-45
A laboratory procedure developed for the estimation of the field performance of hearing protection devices (HPD) was described. The HPD attenuation testing method most commonly used and standardized was the real ear attenuation at threshold (REAT). The HPD/user interface was critical to the attenuation provided, and was especially true of earplugs. A promising approach to reduce divergence between laboratory and field data was to use large groups of untrained subjects for testing, in order to optimize the real world situation. A working group of the American National Standards Institute, S12/WG11 developed a modified laboratory based REAT standard for predictive and labeling purposes, and a field method to actually measure REAT for earplugs under real world conditions. A "subject fit" protocol (SF) was selected as the procedure most likely to provide a useful estimate of real world performance. In order to model the best possible fitting conditions, an alternative procedure, the "informed user fit" (IUF) was also included and considered an optimum fit. A pilot study was conducted in four laboratories with ten subjects each, using the protocol. Results with two types of earplugs tested showed that SF data provided the best estimate of real world attenuation. Precision was also better with the SF procedure than with IUF in terms of repeatability. The possibility of using experienced listeners was tested using 24 novice subjects and 20 experienced subjects, for four HPDs (Mediprint V-51R, Wilson EP-100, E-A-R foam earplug, and Bilsom UF-1 earmuff). SF values exceeded mean real world attenuation values for all four devices, so that the use of more experienced subjects was counterproductive. The manufacturers labeled values exceeded even the IUF condition. The effects of subject selection, training, supervision, and fitting method were less pronounced for the earmuff.
Audiometry; Ear-protectors; Hearing-disorders; Industrial-exposures; Industrial-noise; Measurement-equipment; Noise-induced-hearing-loss; Occupational-exposure; Protective-equipment;
Publication Date
Document Type
Conference/Symposia Proceedings;
Fiscal Year
NTIS Accession No.
NTIS Price
Priority Area
Hearing Loss; Disease and Injury; Noise-induced-hearing-loss;
Source Name
Proceedings, 1992 Hearing Conservation Conference, April 1-4, 1992, Lexington, Kentucky, Office of Engineering Services, University of Kentucky and NIOSH