Artificial flesh material selection for hearing protection evaluation system

Abstract

Developing an advanced hearing protection evaluation system (HPES) in the form of an acoustic test fixture (ATF) allows for characterizing either circumaural or insert-type hearing protection devices (HPDs) in both impulse and continuous noise environments across the dynamic range of human hearing. This is a challenging task since the acoustical transfer paths through flesh contribute to the dynamic response of the system. Current ATFs do not account for the transfer paths through flesh to ear canal. In this study, we investigated several visco-elastic flesh materials numerically using coupled vibro-acoustic simulations, and experimentally using vibration and acoustic excitation methods. Geometrically representative prototypes are being developed using volume computed tomography (VCT) that include detailed features of the skull and flesh structure, so that flesh conducted sound transmission paths can be physically modeled. The HPD on ATF dynamic behavior is compared with the HPD on subject behavior using finite element simulation models developed using the VCT images. The material selection is validated using noise reduction and vibration experiments on the subjects.