Measuring impulse insertion loss of hearing protection devices using high-level impulse noise

The American National Standard, ANSI S12.42-2010 (R2020), specifies how to measure the impulse peak insertion loss (IPIL) for a hearing protection device (HPD) using an acoustic test fixture (ATF) with levels of LPeak = 132, 150, and 168 dB sound pressure level (dB pSPL). fixtures described in S12.42 have ear simulators that are limited below 172 pSPL. Two GRAS 45CB ATFs (with 40BP 40BH 1/4” microphones) were used impulses. Impulses generated .223 caliber Colt AR-15 rifle (160 pSPL) .300 Browning A-Bolt Medallion (167 Each was at same location relative firearm muzzles. IPIL values Hocks Noise Braker earplug measured between 28.8 33.8 dB. standard yielded single just impulses measurement. In proposed revision S12.42, complex transfer function is estimated can be applied arbitrary This paper compares spectral IPILs measurements from two ATFs.