Hemisphere dominance in cochlear implanted children

Cochlear implant is the most technologically sophisticated hearing aid that provides optimal development of hearing and speech. If the peripheral input is enabled the hearing is not achieved yet, because the central mechanisms have been inactive and have to “ earn” how to transmit the acoustic information, how to clean and structure the signal. In most humans, the left cerebral hemisphere is dominant for language processing. The goal of this paper was to investigate if there is a difference in hearing and speech in children with cochlear implants depending on the side of implantation, and the influence of early implantation on hemispheric dominance (the influence of peripheral function on the central one). Twenty prelingually deaf children with cochlear implants, aged between 3 and 11 years, were tested. The children have been rehabilitated according to Guberina’ s verbotonal method in SUVAG Polyclinic, Zagreb. Pure tone audiometry, auditory brainstem responses, middle latency responses, speech audiometry, verbotonal audiometry and psychological evaluation were performed. The results were compared according to lateralisation of function, speech and hearing evaluation. After one year of cochlear implantation and rehabilitation the subjects show significant improvement in hearing level, speech perception and production. Children with cochlear implant in the dominant ear have better hearing than the control group. The first results indicate the significant role of hemisphere dominance on hearing achievement in cochlear-implanted children. The peripheral hearing function influences the central listening abilities and lateralisation in auditory processing.