Spatial release from masking and localization among pediatric cochlear implant users

This study aimed to assess spatial hearing abilities in children using bimodal hearing devices. (1) comparing spatial release from masking (SRM) in monaural and bimodal conditions; (2) comparing horizontal localization error across conditions; and (3) examining the correlation between SRM and localization error.

A cross-sectional, repeated-measures design was used with 43 Kannada-speaking children (aged 4-10 years) with bilateral severe-to-profound hearing loss, fitted with a cochlear implant (CI) in one ear and a hearing aid (HA) in the other. Spatial hearing was assessed using phonemically balanced word lists in noise (SRM task) and white noise bursts from eight loudspeakers (localization task). SRM was calculated as the difference in speech identification scores (SIS) between collocated and spatially separated speech-noise conditions. Localization was measured using root mean square (RMS) error.

SRM was significantly higher in the bimodal condition (M = 3.09) than monaural (M = 1.23), t (42) = 3.15, p < 0.001, d = 0.49. Localization accuracy also improved with bimodal hearing (M = 82.27° vs. 105.88°), F (1,42) = 100.79, p < 0.001, η_p² = 0.706. A significant negative correlation (r = -0.518, p < 0.001) was found between SRM and localization error.

Bimodal hearing significantly enhances spatial hearing in children, improving both speech-in-noise perception and localization. The correlation between SRM and localization suggests shared spatial processing mechanisms. These findings support the clinical importance of bimodal device use, especially in settings where bilateral implantation is not feasible, and highlight the need for individualized auditory management.