Cochlear implants in the Third Millennium.

Before outlining some important directions for cochlear implant research in the Third Millennium, it is worth reviewing a few of the achievements of the Second Millennium. As recently as the 1960s and 1970s, many scientists and clinicians claimed that successful cochlear implants were not possible in the foreseeable future. However, over the last 30 years, many of their objections have been overcome. We have learned how to partially reproduce the coding of sound with electrical stimulation; to im­ plant the cochlea without significant damage; and to process speech so that it can be understood. Furthermore, improvements in speech perception have occurred over the last 20 years, principally because of the selection of more frequency information and its presentation on a place-coding basis. . After establishing the benefits of the cochlear Implant in adults, three children were implanted in 1985 and 1986 in Melbourne. This was the start of an international trial by Cochlear Limited to determine whether the multiple­ electrode cochlear implant would also benefit chIldren who became deaf early in life or were born deaf. The trial showed that 60% of children born deaf were able to un­ derstand some open-set speech using electrical stimula­ tion alone, and the majority had significant help in lip­ reading. The U.S. Food & Drug Administration approved the device as safe and effective for children aged 2 years and older in 1990. Subsequently, in a study of children in Melbourne, BKB sentence scores were compared against age at implanta­ tion and considerable variability in results was found (see Fig.' 1). However, a curve fitting of the data empha~ized that the results were better in younger children, and, If ex­ trapolated back, could have been even better if the child was implanted before 2 years of age (Fig. I).