[An implant for stimulation of the acoustic nerve with 12 channels].
A portable hearing aid for direct stimulation of the eighth cranial nerve was developed and translated into reality. The system (Fig. 1) consists of two components, the portable transmitter and the receiver to be implanted in the mastoid. The speech signal, received in a microphone, is divided into 12 frequency bands in the transmitter (Fig. 2). The outputs are transferred via a vocoder system with pulse amplitude modulation and using a small transmitting device for signals and for energy to the receiver. The implantable receiver (Figs. 3 and 8) transfers the signals in the 12 channels into the electrical stimuli of the electrodes which are pushed into the nerve in a form of a bunch (Fig. 9). In this manner--similar to normal hearing, although much coarse--tonotopic frequency-place transformation can be achieved.