Visual localization of sounds

Circumscribed hemispheric lesions in the right hemisphere have been shown to impair auditory spatial functions. Due to a strong crossmodal links that exist between vision and audition, in the present study, we have hypothesized that multisensory integration can play a specific role in recovery from spatial representational deficits. To this aim, a patient with severe auditory localization defect was asked to indicate verbally the spatial position where the sound was presented. The auditory targets were presented at different spatial locations, at 8◦, 24◦, 40◦, 56◦ to either sides of the central fixation point. The task was performed either in a unimodal condition (i.e., only sounds were presented) or in crossmodal conditions (i.e., a visual stimulus was presented simultaneously to the auditory target). In the crossmodal conditions, the visual cue was presented either at the same spatial position as the sound or at 16◦ or 32◦, nasal or temporal, of spatial disparity from the auditory target. The results showed that a visual stimulus strongly improves the patient’s ability to localize the sounds, but only when it was presented in the same spatial position of the auditory target.