Four protectors in search of a rating system

Abstract

The EAR Classic, V-51R, Howard Leight Max-1 and EAR Express Pod insert earplug hearing protection devices (HPDs) were tested at the NIOSH Hearing Protector Laboratory using real-ear attenuation at threshold (REAT) according to ANSI S12.6-1997 Method B subject-fit (SF) and ANSI S3.19-1974 experimenter-fit (EF) methods. Several subject panels were created from the NIOSH subject pool which permitted comparisons to the manufacturer’s REAT data published on the device’s label. For the Classic, NIOSH data agreed with the manufacturer’s data. However, for the other devices, the manufacturer’s data typically produced higher noise reduction ratings (NRRs) than the NIOSH data. The subject-fit NRR, NRR(SF), results were 17, 1, 12, and 10 dB for the Classic, V-51R, Max and Express, respectively. The REAT variances for the Bilsom V-51R data and the Howard Leight Max were significantly smaller than the NIOSH variances. The NIOSH recommendation that SF data, measured according to ANSI S12.6-1997, be used to rate the performance of a hearing protector, is supported by these results. Application of the NIOSH and OSHA derating schemes to EF NRR either overestimated or underestimated the NRR(SF). [Portions of work supported by the U.S. EPA IA 75090527.]