Evaluation of an earphone-support device for measuring earplug attenuation

A new procedure for determining the attenuation of earplugs with a standard audiometric headset was evaluated. The procedure utilized a device that supports a conventional supraaural earphone cushion (MX-41/AR) such that it does not contact the pinna or the earplug during threshold measurement. The attenuation provided by a foam earplug was estimated on a group of normal-hearing subjects using this method. The resulting attenuation values were compared to data obtained using sound field (ANSI S12.6-1984) methods, and to values obtained by simply placing the earphone on the pinna. Results suggest that the test re-test reliabilities of both the earphone-support method and the earphone-only method were comparable to that of the sound field procedure. Also, of the four test frequencies employed (1, 2, 3 and 4 kHz), the closet correspondence between attenuation estimates obtained using the ANSI procedures and estimates obtained with the support device occurred at 1 and 2 kHz.