Sound source localization from tactile aids for unilateral cochlear implant users

Abstract

The present research asks whether two tactile aids with directional microphones, by providing additional inter-channel level information and etc., could help unilateral cochlear implant (CI) localize sound sources. For normal hearing subjects, sound source localization based on tactile vibration cues alone can be as accurate as auditory localization in the frontal horizontal plane (Gescheider, 1970). CI users may as well benefit from additional tactile aids just as normal hearing people do. The current study uses two bone-anchored hearing aids (BAHA) as sources of tactile vibration. The two BAHAs, bonded together by a special gadget to maintain a particular distance and angle, both have directional microphones, and are programed so that one point to the front-left side and the other to the front-right side. Unilateral CI users voluntarily participated in the experimental study. Wide band noise stimuli were presented at 65 dB SPL. The subjects hold one BAHA in each hand and do localization tasks with (1) CI only and (2) with CI and tactile sensation combined. Preliminary data shows CI users can get some benefit from the additional information provided by tactile aids in 360 degree localization (45 degree spacing) on the horizontal plane.