Abstract:
The purpose of this study is to determine how well normal-hearing humans can localize sound sources while wearing protective headgear with and without hearing protection. Six subjects will participate in a source identification task to be conducted in an anechoic chamber. On each trial the stimulus (a 100-ms broadband source) will be presented from one of 20 loudspeakers arrayed in a semicircular arc, and the subject must state which loudspeaker emitted the sound. The arc spans 160(degrees) in the horizontal plane at ear level and is about 1.8 m distant from the subject. Each subject will be tested in eight conditions, involving various combinations of wearing protective headgear and three types of earplugs: the EAR plug and the Etymotic ER15 and ER25 ``musician's'' earplugs. In addition, testing will be conducted at each of two orientations: frontal (center of the array at subject's midline) and lateral (center of the array at 90(degrees) azimuth). Results are expected (a) to reveal whether the Etymotic earplugs (which are designed to attenuate equally across a broad frequency range) preserve localization accuracy, and (b) to quantify the interactive effects on localization performance of protective headgear and earplugs. [Work supported by NIDCD and NOHR.]