Chapter 27 New hardware for analog and combined analog and pulsatile sound-encoding strategies

Abstract

Development for cochlear implants of primarily analog design focuses in two directions. The first direction is miniaturization. A behind-the-ear (BTE) speech processor has been developed which can replace the body-worn processor for approximately 90% of the users of a MED-EL cochlear implant and works with two 1.4 V hearing aid batteries for between seven and twelve days. Consonant, vowel and sentence testing and patient questioning revealed that the BTE speech processor demonstrates a significant improvement in speech understanding compared to the body-worn processor, and that the patients' device acceptance is superior for the BTE processor. The result of the second direction for our cochlear implant development is the multichannel cochlear implant, CAP, with combined analog and pulsatile stimulation. It aims at complementing the information from the broad-band analog signal by adding spectral information, that is, tonotopic information. This device is capable of simultaneously stimulating one electrode channel with a broad-band analog signal and one of eight electrode channels with a pulsatile signal. The system can also be used for purely analog or for purely pulsatile stimulation. Preliminary results with the first recipient of a CAP cochlear implant system demonstrate that the device works as expected.