Effects of Hearing Loss and Hearing Aid Directionality on Performance and Orienting Behavior in a Multi-Talker...

Hearing-impaired (HI) individuals experience substantial difficulties with speech perception in reverberant environments with multiple simultaneous talkers. Hearing aids equipped with directional microphones are designed to support listening in such situations, but their effectiveness can be compromised by changes in target talker location and listener head movements. The present study used a complex audiovisual search task to investigate performance and orienting behavior for listeners with and without hearing loss under unaided and aided conditions. The authors hypothesized that hearing loss would lead to poorer performance and more complex orienting behavior, and that directional microphone processing would affect performance and orienting behavior further due to altered spatial cues.

Twenty normal-hearing (NH) and 22 HI participants completed a task requiring them to locate and identify a target narrative in a moderately reverberant audiovisual environment containing multiple competing narratives. The environment was rendered using a 64-channel loudspeaker array and virtual-reality glasses, with 15 possible target azimuths. Head and eye movements were tracked using the built-in sensors of the virtual-reality glasses. Testing was conducted under unaided conditions and aided conditions with either omnidirectional or directional microphone settings. Task performance was assessed using response accuracy, localization error, and response time. Orienting behavior was quantified using misorientation rate, head-gaze ratio, scan-path efficiency, and head and gaze orientation offsets.

Compared with the NH participants, the HI participants showed significantly lower response accuracy, larger localization errors, and longer response times across all conditions. They also exhibited less direct search behavior, characterized by more frequent initial head turns away from the target and a greater reliance on eye rather than head movements. When aided, the NH participants showed reduced accuracy and increased localization errors, particularly with the directional microphone setting, and they relied slightly more on head movements. For both groups, eye-movement complexity increased under aided conditions, with the HI participants showing more complex gaze patterns. Unlike the NH participants, the HI individuals often aligned their gaze-but not their head-with the target location when responding.

The results demonstrate fundamental differences in task performance and orienting behavior between HI and NH listeners in complex multi-talker environments. Although directional microphones are designed to improve speech understanding in noise, they introduce challenges in tasks that require accurate target localization. Overall, these findings highlight both the impact of hearing loss and the limitations of hearing aid directionality in complex listening environments.