Implementation of a real-time, digital vocoder for tactile hearing prostheses

A microprocessor-based vibrotactile vocoder is described that offers important advantages over its analog counterpart. Digital implementation provides more flexibility and precision. The system simulates, in real-time, the characteristics of the one described by Searle, et al. [2] and is intended for use with a linear array of sixteen miniature vibrators. Algorithms used to implement the digital signal processing functions in fixed point arithmetic are described. Dynamic range and noise are measured and discussed. The system will be incorporated into a wearable vibrotactile unit so that the concept of using the skin as an alternate sensory input for speech communication for the hearing handicapped can be evaluated under natural conditions of acoustic signal and noise.