Effects of low-frequency thresholds on sound-source identification in the frontal horizontal plane using interaural time difference cues

Abstract

Eight listeners with symmetric sensorineural hearing loss were investigated using a sound-source identification paradigm, to study localization abilities in noise for sources in the frontal horizontal plane. Stimulae were low-pass filtered click trains making available the primary cue of interaural time differences. Compared to performance of a normally hearing reference group, the listeners with sensorineural hearing loss exhibited systematic deficits in localization ability which were strongly related to hearing level. However, parallel detection experiments also showed deficits and the localization data might be a function of simple audibility. The listeners were further tested using a number of binaural hearing aid fittings for which detectability was returned to levels displayed by the normal-hearing listeners. Aided localization ability did improve but still showed residual deficits compared to the normal-hearing references and, furthermore, still had a systematic relationship with hearing level. The gradient of this relationship was approximately half that in the unaided data. The results suggest that sensorineural hearing loss compromises the use of interaural time difference cues to achieve sound-source identification and that the deficit is in part independent of audibility considerations.