The effects of hearing threshold asymmetry on spatial release from masking

Hearing loss is a leading contributor to speech-in-noise (SIN) difficulties, often exacerbated by declines in binaural processing. Asymmetry in hearing thresholds may further reduce benefit from spatial separation. However, it remains unclear which audiometric measure, and what degree of asymmetry, impacts binaural performance. QuickSIN, a monaural SIN task, may reveal functional differences and offer a more sensitive measure of asymmetry. This study investigated how asymmetries in pure-tone thresholds, pure-tone average (PTA), and QuickSIN signal-to-noise ratio (SNR) relate to spatial release from masking (SRM) under headphones. It was hypothesized that QuickSIN SNR asymmetry would best predict SRM performance. Participants (n = 43; 25 female; age range: 21–78 years) had normal to moderate sensorineural hearing loss with varying asymmetries. SRM was measured using the Coordinate Response Measure (CRM), with the target fixed at 0°, and same-sex speech maskers at 0°, ±5°, and ±45°. Individuals with greater QuickSIN asymmetry showed significantly poorer CRM performance at 0° (p = 0.005) and 45° (p = 0.018). No interaction was found between hearing asymmetry and masker angle, suggesting that SRM is relatively robust to SIN asymmetry. These findings support using speech-based measures to assess functional asymmetry and counsel patients on advantages of utilizing spatial cues.