Angkana Lertpoompunya ^1* Erol J. Ozmeral ² Nathan C. Higgins ^2* David A. Eddins ³

• ¹ Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
• ² University of South Florida, Tampa, United States
• ³ University of Central Florida, Orlando, Florida, United States

Head movement plays a vital role in auditory processing by contributing to spatial awareness and the ability to identify and locate sound sources. Here we investigate head-orienting behaviors using a dualtask experimental paradigm to measure: a) localization of a speech source; and b) detection of meaningful speech (numbers), within a complex acoustic background. Ten younger adults with normal hearing and twenty older adults with mild-to-severe sensorineural hearing loss were evaluated in the free field on two head-movement conditions: (1) head fixed to the front and (2) head moving to a source location; and two context conditions: (1) with audio only or (2) with audio plus visual cues. Headtracking analyses quantified the target location relative to head location, as well as the peak velocity during head movements. Evaluation of head-orienting behaviors revealed that both groups tended to undershoot the auditory target for targets beyond 60° in azimuth. Listeners with hearing loss had higher head-turn errors than the normal-hearing listeners, even when a visual location cue was provided. Digit detection accuracy was better for the normal-hearing than hearing-loss groups, with a main effect of signal-to-noise ratio (SNR). When performing the dual-task paradigm in the most difficult listening environments, participants consistently demonstrated a wait-and-listen head-movement strategy, characterized by a short pause during which they maintained their head orientation and gathered information before orienting to the target location.