Microcontroller based receiver stimulator for auditory prosthesis

Abstract

The Auditory Prosthesis (AP) is an electronic device that is designed to provide hearing sensations to people who are profoundly deaf. The AP mimics the normal hearing operation by stimulating the auditory nerve with an electric current allowing the hearing impaired persons to understand the speech. The AP system consists of two functional units namely Body Worn Speech Processor (BWSP) and Receiver Stimulator. The laboratory model BWSP is available. The prototype model Receiver Stimulator for Auditory Prosthesis(RSAP) consists of High-speed Microcontroller DS89C420 based Speech Decoder, DAC, ADC, constant current stimulator, encoder, combinational circuit for channel selection, switch matrix and simulated resistance array. The laboratory model speech processor is used to implement the Continuous Interleaved Sampling (CIS) speech processing algorithm which generates the information required for stimulation based on the audio information. Speech Decoder receives the encoded speech data via RF transcutaneous from speech processor. The speech data format and generation of biphasic stimulation pulses based on the CIS stimulation strategy are covered. Multi-channel auditory Prosthesis with eight electrodes that are simulated as resistance array can be driven by the prototype auditory Prosthesis for testing its performance. The implementation aspects of CIS algorithm are validated using the test data of speech samples generated by the laboratory model Body worn speech processor. The results are presented using prototype model of auditory Prosthesis and simulated electrode resistance array with a high-speed data acquisition system and found satisfactory results.