Effects of training on hearing protector attenuation

Abstract

The effect of training instruction, whether presented as the manufacturer's printed instructions, a short video training session specific to the product, or as a one-on-one training session was evaluated using four hearing protection devices with eight groups of subjects. Naïve subjects were recruited and tested using three different forms of training: written, video, and individual training. The group averages for A-weighted attenuation were not statistically significant when compared between the video or the written instruction conditions, regardless of presentation order. The experimenter-trained A-weighted attenuations were significantly greater than the written and video instruction for most of the protectors and groups. For each earplug, the noise reduction statistic for A-weighting (NRS A ) and the associated confidence intervals were calculated for the 80 th and 20 th percentiles of protection. Across subject groups for each protector, the differences between NRS A ratings were found to be not statistically significant. Several comparisons evaluating the order of testing, the type of testing, and statistical tests of the performance across the groups are presented.

Evaluation of impact and continuous noise exposure, hearing loss, heat stress, and whole body vibration at a hammer forge company.

“…However, our testing of the attenuation for these hearing protectors in the mannequin head and the range of attenuation achieved by subject fit testing show that more noise attenuation than the manufacturers' NRR may be possible with well-fitting hearing protectors. In contrast, subject fit test data also show that poorly fitting hearing protection provides attenuation much worse than the manufacturers' reported NRR [Berger et al 1996;Berger et al 1998;Franks et al 2000;Joseph et al 2007;Murphy et al 2011]. …”

“…The hearing protector attenuation used to determine the "estimated protection level" were based on previous subject fit-test studies, which estimated an average attenuation of 28-29 dB for these hearing protectors [Murphy et al 2011]. The wide black horizontal line is the average frequency-specific estimated protection level, and the progressively lighter shading extends to three standard deviations.…”

In-depth survey report: comparison of the performances of three acoustic test fixtures using impulse peak insertion loss measurements, Rudyard, Michigan.

“…Although the current study did not evaluate a formable earplug, unpublished impulse data collected by NIOSH at the US Army Aeromedical Research Laboratory at Fort Rucker indicated that the IPIL increased with the insertion depth. In general, the insertion depth is a critical factor for achieving an adequate amount of protection when exposed to continuous noise (Murphy et al, 2009;Murphy et al, 2011); therefore, insertion depth should be critical to providing protection from impulse noise.…”

In-depth survey report: comparison of two acoustic test fixtures for measurement of impulse peak insertion loss.

“…Although this study did not evaluate a foam earplug, impulse data collected by NIOSH at the US Army Aeromedical Research Laboratories at Fort Rucker indicates that the IPIL will vary with the insertion depth. In general, the insertion depth is a critical factor for achieving an adequate amount of protection when exposed to continuous noise Murphy et al 2011); therefore, it will be critical to providing protection from impulse noise.…”