TREATMENTS FOR PARTIAL DEAFNESS USING COMBINED ELECTRIC AND ACOUSTIC STIMULATION OF THE AUDITORY SYSTEM

Abstract

This paper provides a summary of the experience to date with (1) combined electric and acoustic stimulation of the auditory system (combined EAS) for persons with some residual hearing at low frequencies, and (2) a procedure called “partial deafness cochlear implantation” (PDCI) for persons with higher levels of residual hearing at low frequencies, including persons with normal or nearly normal hearing at 500 Hz and lower frequencies. The paper also presents new results on the dependence of outcomes according to the levels of the residual hearing. In broad terms, both combined EAS and PDCI are highly beneficial treatments, especially for speech reception in noise. In some cases synergistic effects are found, in which the speech reception score for combined EAS or PDCI is greater than the sum of the scores for electric or acoustic stimulation only. In addition, the new results demonstrate that patients with high levels of residual hearing (PDCI levels) receive benefits from cochlear implantation that are at least as great as the benefits received by patients with lower levels of residual hearing. This finding strongly supports the concept of providing cochlear implants for persons with substantial residual hearing at low frequencies; indeed, a “point of diminishing returns” has yet to be identified.