Individual fit-testing of earplugs: A review of uses

Abstract

Individual fit-testing of earplugs is an exciting new trend in hearing conservation. This article reviews how this technology is being used to protect noise-exposed workers. Earplug fit-testing systems are becoming more commercially available and more feasible for field use. Individual fit-testing is no longer used only for research investigations but is being incorporated in Hearing Conservation Programs (HCP) to improve training, document protection and evaluate the effectiveness of the hearing protector element of an effective HCP.

Suitability of commercial systems for earplug individual fit testing

“…The VeriPRO results do not compare well with the benchmarks, reflecting the finding reported in [10] in which, for 16 subjects, the SNR of 10 different earplugs was compared with the PAR provided by VeriPRO. According to the latter study, VeriPRO underestimates attenuation and differences vary with the earplug used.…”

“…The ''pseudo SNR'' was calculated in the same way as a normal SNR (defined in [1]), using the subject individual octave band attenuations obtained with REAT as inputs, but ignoring the standard deviation (null standard deviation). The PAR calculation is different for each system: the calculation methods applied to the EARfit and VeriPRO systems can be found in [10] -Appendix A. The VeriPRO PAR calculation is similar to the Noise Reduction Rating (NRR) except that calculations are performed for a narrower bandwidth and no corrections for between subject variability and À3 dB de-rating are applied.…”

“…Howard Leight implements this method in its VeriPRO fit testing. An independent test using this system, reported in [10], was performed by E. Kotarbinska on 10 different earplugs. Although expressed in average values (SNR, NRR and NRRsf), comparisons reveal that the REAT is grossly underestimated.…”

Preventing Noise-Induced Hearing Loss

“…A sealed earplug will also offer some resistance to being removed. For these and other fitting tips, see Berger [21] and Schulz [22].…”

Measurements of earplug attenuation under supra-aural and circumaural headphones

“…Fit-testing can also provide documentation of HPD adequacy in cases of possible noise-induced threshold shift, for defense against workers ' compensation claims, for compliance with federal or state regulations, and for assessment of overall HPD effectiveness in a hearing conservation program. Methods of HPD fi ttesting include microphone-in-real-ear (MIRE) procedures, loudness balancing procedures, and real-ear-attenuation-at-threshold (REAT) procedures (Berger et al, 2008;Hager, 2011;Schulz, 2011). MIRE and loudness-balancing procedures are described elsewhere in the literature and are not discussed in this paper.…”