Needs and Procedures for Field Testing of Hearing Protectors.
Noise-Con 81, Proceedings of the 1981 National Conference on Noise Control Engineering, Raleigh, North Carolina, 8-10 June, 1981 1981:141-146
Research was performed to develop a practical procedure for field testing of hearing protectors on each individual who wears them. Two short variations of a method for measuring the threshold of hearing with and without an earplug inserted were investigated: a third octave band method centered at 1000 hertz (Hz), and a midline lateralization (ML) method in which the subject adjusts the sound in the tested ear to balance sound at a standard intensity in the other ear. These methods were compared with the threshold shift (TS) procedure of Michael, which uses nine different third octave bands of noise. For the 1000Hz method, in the range between 10 and 30 decibels (dB), the results agreed with TS within 2.0dB for earplug 1 and 2.1dB for earplug 2. For the ML method, slopes of the regression lines for TS results on ML results were 0.69 for earplug 1 and 1.03 for earplug 2. In the range 10 to 30dB, all points but one were within 3dB of an ideal line having a slope of unity and an intercept of zero. An estimate of each person's attenuation (personal attenuation factor, PAF) was defined as the one sided lower 95 percent confidence limit of the mean of the test values for an individual. For the standard deviation of values found in the experiments (6dB), the optimal number of tests needed was five, which would require about 30 minutes for measurements on both ears of a single individual. Equipment costs were estimated to be 2500 dollars for the ML procedure and 5000 dollars for the 1000Hz procedure. Possible differences in scheduled versus candid testing were discussed, although no such differences were found in these field tests. The author concludes that, whatever the expenses would be, the benefits derived from knowing how a hearing protector is performing on a person might more than balance the costs of individual testing.
Noise-control; Ear-protection; Acoustical-measurements; Ear-protectors; Noise-induced-hearing-loss; Sound-attenuation; Hearing-acuity; Noise-protection; Screening-methods; Workplace-studies;
Royster-LH; Hart-FD; Stewart-ND;
Hearing Loss; Disease and Injury; Noise-induced-hearing-loss;
Noise-Con 81, Proceedings of the 1981 National Conference on Noise Control Engineering, Raleigh, North Carolina, 8-10 June, 1981