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Improvement of sound source localization abilities in patients bilaterally supplied with active middle ear implants
Viktor Koci1, Josef Seebacher1, Viktor Weichbold1
1a Department for Hearing, Speech and Voice Disorders , Medical University of Innsbruck , Innsbruck , Austria ;
Conclusions:
Patients, who are bilaterally supplied with active middle ear implants, perform slightly better in sound localization tasks than when unilaterally aided or unaided.
Objectives:
To investigate the impact of bilateral use of active middle ear implants on sound source localization in the horizontal plane in patients with a sloping moderate-to-severe hearing loss.
Methods:
Ten adults supplied with Med-EL Vibrant Soundbridge systems (VSB) in both ears participated in the study. Four listening conditions were tested: unaided, aided with VSB on left or right ear and on both sides. In each condition the subjects had to judge the direction of broadband noises delivered randomly across a semicircular array of 11 loudspeakers arranged in an anechoic chamber.
Results:
When unaided or bilaterally aided, the subjects localized on average 40% of the stimuli correct; when unilaterally aided (left or right), this rate dropped to 20-30% in either condition. Precision of sound localization was highest when bilaterally aided, i.e. the mean RMS angular error was 10°, and lowest when unilaterally aided, i.e. 15°. This is in line with bilateral hearing aid users, who show similar performance in sound localization tasks.

