DSP and Microcontroller based Speech Processor for Auditory Prosthesis

Auditory Prostheses is necessary for the hearing impaired personnel. Auditory Prostheses is an artificial replacement of damaged inner ear using external body worn speech processor and internal receiver-stimulator for stimulating auditory nerve via electrode array that enables understanding the speech by brain. Speech processor receives an external sound or speech and generates encoded speech data bits for transmission to receiver-stimulator. Development of the Speech Processor of Auditory Prostheses (SPAP) is based on the Analog Devices Digital Signal Processor ADSP-2181 is described. The Dalls DS89C420 micro controller is used as data encoder to send speech information from speech processor to receiver-stimulator via RF transcutaneous link. The system comprises a speech processor, micro-controller based data encoder, radio frequency transmitter, receiver-stimulator, and an electrode array of six electrodes. A six channel Continuous Interleaved Sampling (CIS) algorithm is implemented for the speech processor. A multi-channel cochlear implant of 6 electrodes or simulated resistance array can be driven by the receiver-stimulator for testing its performance. The implementation aspects of CIS algorithm are validated using the test data of speech samples. The results are presented using laboratory model of receiver-stimulator and simulated electrode resistance array with a high-speed data acquisition system.