Impact of Acute Versus Chronic Unilateral Hearing Loss on Head Movement in a Novel Binaural Task

Individuals with single-sided deafness (SSD) may develop adaptive listening strategies with head movement patterns to optimize monaural localization and speech-in-noise understanding. Granular understanding of adaptive behaviors may better inform rehabilitation for SSD. We aimed to characterize head movements during a combined localization and speech-in-noise task to understand how adaptive behaviors emerge.

Prospective study from a tertiary referral center with 16 subjects with normal hearing (NH) and 15 SSD subjects. Sentences were played in a semi-anechoic chamber from one of 24 speakers in a 360° azimuthal configuration with a variable signal-to-noise ratio. Head position was captured via an electromagnetic tracking system. NH subjects completed the task twice, once with a deeply-seated earplug and supra-aural earmuff to simulate acute unilateral hearing loss and once unoccluded. Outcome measures included localization accuracy (mean absolute error, slope across targets), head movement (onset delay, total response time, total head displacement), and speech-in-noise performance.

Unoccluded NH subjects displayed accurate localization, minimal movement delay, rapid response time, low total head displacement, and high speech-in-noise percent correct compared to the occluded condition and SSD subjects. Localization accuracy and SIN performance were comparable between NH occluded and SSD; however, the groups had distinct head movement patterns.

Acute unilateral hearing loss leads to sharp declines in localization accuracy and speech-in-noise performance. In SSD, difficult listening conditions may prompt the development of distinct head movement patterns over time. This work provides key initial insight into adaptive listening strategies that individuals with SSD may acquire and utilize in complex listening environments.