Cochlear Implant Work at UW

Editor: Here's a brief introduction to what's going on in the CI world at the Virginia Merrill Bloedel Hearing Research Center at the University of Washington. This article first appeared in their online newsletter at
http://depts.washington.edu/hearing/pdf/bloedelsound.pdf

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The cochlear implant is a device allowing the deaf to hear. The cochlear implant was developed initially in the 1960's and 1970's. The FDA approved the device and it became widely available in the mid 1980's. Today, more than 100,000 people world-wide use a cochlear implant. Early devices delivered electrical charge to the auditory nerve via electrodes implanted in the inner ear. Research and development has lead to numerous advances in the device, such as the use of more electrodes and "interleaved", non-simultaneous electrical pulses, have improved the ability of users to resolve the acoustic spectrum of high vs. low frequencies. These advances have enabled the implant to become one of the most remarkable biomedical devices available. The risks of use are minimal and benefits are enormous. Implant users who have lost their hearing in adulthood, or children who received an implant at an early age, have been highly successful users. These patients, who formerly received no benefit from a hearing aid, can usually understand speech well and often can converse on the telephone. While the cochlear implant has been a huge success, the device has some shortcomings. Namely, patients often complain they have great difficulty understanding speech in noisy environments, and they complain that music sounds terrible. Implant users, for example, have great difficulty hearing melodies or picking out individual instruments or voices in a musical group.

At the Virginia Merrill Bloedel Hearing Research Center (VMBHRC), we are engaged in research to improve the cochlear implant. Dr. Jay T. Rubinstein, Director of the Center, has invented an approach for improving hearing with a cochlear implant. The approach, referred to as "conditioning", conditions the nerves with low-level electrical pulses, making the auditory nerves more ready to respond. Spontaneous nerve activity is present in normal-hearing people, but not in the deaf. The nerves lie mostly dormant. Conditioning introduces low-level electrical pulses to stimulate spontaneous activity and make the auditory nerves more alive. The approach helps the implant create nerve impulses that are more like normal nerve impulses than the nerve impulses created by previous technology.

Dr. Rubinstein's conditioning technology and has only been implemented at three laboratories around the world, under his direction. Two implants also can increase the chances that the user will understand speech, because they are two implants provides more information. For example if some frequency range does not respond on one side, it might respond on the other or both. Having more information can only help their hearing. The combination of conditioning and two implants has, to date, proven hugely beneficial in the one user who has received this treatment at Bloedel. Her speech understanding has improved about 30 percentage points since she had one implant without the conditioning. Work in this area continues as more patients receive conditioning, a second implant or both.