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Science Capsule: Cochlear Implants

The development of the multi-channel cochlear implant has made it possible to restore the perception of sound to people who are profoundly deaf or severely hard of hearing (HoH). In contrast to hearing aids, which amplify sound, cochlear implants directly stimulate the auditory nerve.

Over the past two decades, NIDCD-supported research led to major advances in multi-electrode signal processing, as well as in understanding the benefits of early implantation in children and the possible benefits of implantation in both ears. Because of this research, we now know that children with hearing loss who receive a cochlear implant within the first two years of life will typically experience a smaller gap in language skills and will be more likely to succeed in mainstream classrooms.

According to the U.S. Food and Drug Administration (FDA), in December 2010, approximately 219,000 people worldwide have received cochlear implants, including approximately 42,600 adults and 28,400 children in the United States. Roughly 40 percent of children who are born profoundly deaf now receive a cochlear implant, which is a 25 percent increase from five years ago. The rise in cochlear implant use among eligible people between 2000 and 2010 exceeded the target set in the U.S. Department of Health and Human Services’ (HHS) Healthy People 2010 (a set of science-based 10-year national health objectives), and a new target is being developed for Healthy People 2020.

NIDCD-supported scientists continue to improve cochlear implant technology through the development of noise-reduction signal processing and innovative electrode designs. For example, insertion of traditional cochlear implant electrodes can damage hair cells throughout the cochlea, so researchers are investigating methods to preserve residual hearing in eligible individuals by implanting a shorter electrode array. In addition, animal studies are underway to assess the risks and benefits of a new electrode design that is positioned inside the auditory nerve, with the hope this will provide an improved sense of hearing in crowds and other social situations in which more than one person is speaking. NIDCD researchers continue studies with children who received cochlear implants at a young age to determine what factors contribute to successful language learning and subsequent academic performance. Continued research to assess how current users benefit from a cochlear implant in one ear, along with a cochlear implant or a hearing aid in the other ear, will help inform the design of the next generation of implants.