Effects of training on hearing protector attenuation.

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.

Results of the National Institute for Occupational Safety and Health-U.S. Environmental Protection Agency interlaboratory comparison of American National Standards Institute S12.6-1997 Methods A and B.

The National Institute for Occupational Safety and Health and the Environmental Protection Agency sponsored the completion of an interlaboratory study to compare two fitting protocols specified by ANSI S12.6-1997 (R2002) [(2002). American National Standard Methods for the Measuring Real-Ear Attenuation of Hearing Protectors, American National Standards Institute, New York]. Six hearing protection devices (two earmuffs, foam, premolded, custom-molded earplugs, and canal-caps) were tested in six laboratories using the experimenter-supervised, Method A, and (naive) subject-fit, Method B, protocols with 24 subjects per laboratory. Within-subject, between-subject, and between-laboratory standard deviations were determined for individual frequencies and A-weighted attenuations. The differences for the within-subject standard deviations were not statistically significant between Methods A and B. Using between-subject standard deviations from Method A, 3-12 subjects would be required to identify 6-dB differences between attenuation distributions. Whereas using between-subject standard deviations from Method B, 5-19 subjects would be required to identify 6-dB differences in attenuation distributions of a product tested within the same laboratory. However, the between-laboratory standard deviations for Method B were -0.1 to 3.0 dB less than the Method A results. These differences resulted in considerably more subjects being required to identify statistically significant differences between laboratories for Method A (12-132 subjects) than for Method B (9-28 subjects).

Fit testing of hearing protectors.

OSHA's mandate to offer a variety of suitable hearing protectors to noise-exposed workers in no way guarantees a good fit or adequate protection.

Putting the personal back into PPE: hearing protector effectiveness.

The lessons learned from this field study of hearing protector attenuation can be distilled for the safety manager into two recommendations: 1) One-on-one training is the best predictor of whether workers will achieve a good fit with their ear plug. While the sheer volume of individual training may appear overwhelming in some facilities, the results were significant and measurable in terms of protecting hearing. 2) If a worker obtains a poor fit with a particular style of ear plug, trying a different pair of ear plugs typically achieves an acceptable attenuation. But even if the different ear plugs do not provide proper fit, the employer still has the option of fitting ear muffs to that worker. Field testing of hearing protectors bridges the gap between the laboratory estimates of attenuation and the real-world attenuation achieved by workers as they normally wear the protectors. But most importantly, it restores the personal back into Personal Protective Equipment. And when it comes to hearing protection, achieving good protection is all personal.