An Automated System for Sound Localization Testing in Hearing-Impaired Listeners

Sound localization is a fundamental component of auditory perception, yet its clinical assessment remains technically demanding. Although free-field localization tests using semicircular loudspeaker arrays are considered the gold standard, many existing protocols rely on examiner-driven procedures and provide limited guidance for the functional interpretation of localization errors. An automated sound localization protocol that combines standardized stimulus delivery and response acquisition with a function-oriented interpretive framework is presented. Stimuli are presented from predefined azimuthal positions under controlled conditions, participant responses are collected via a graphical interface, and localization performance metrics are computed automatically upon test completion. Importantly, quantitative localization errors are subsequently translated into clinically meaningful categories using the International Classification of Functioning, Disability and Health (ICF)-based classification framework. The protocol was applied to 34 adults, including 20 with normal-hearing and 14 with single-sided deafness (SSD). Participants were tested under standardized conditions, and their performance was quantified using the root mean square error (RMSE) and mean absolute error (MAE). Outcomes were functionally classified according to the ICF framework. Normal-hearing listeners consistently demonstrated low localization errors corresponding to no or mild impairment, whereas the SSD group demonstrated larger angular errors and higher ICF-defined impairment levels. By integrating an automated localization protocol with an ICF-based interpretive scale, this approach facilitates reproducible assessment of horizontal sound localization while enabling clinically relevant interpretation of spatial hearing deficits. The proposed framework supports examiner-independent testing and may be applied in clinical and research settings to characterize localization performance across listener groups and interventions.