Report: Single-board general-purpose speech recognition system

This paper describes a single-board implementation of an isolated word recognizer based on the principles of linear predictive coding (LPC) and dynamic time warping (DTW). The recognizer requires only a serial (RS-232) terminal, power supply, and microphone for operation, and may be used to add speech input capability to any serial terminal connected to a host computer. Key elements of the recognizer include a custom integrated circuit for DTW-based pattern matching, a single-chip implementation of real-time LPC feature measurement, and a 16-bit microprocessor for control, communication, and decision functions. As a result of the custom integrated circuit and multiple processor architecture, pattern matching speed is increased by a factor of 50 over an earlier design with no custom integrated circuits and without pipeline processing capabilities, and proceeds on one word while LPC measurement on the next is in progress, increasing speech throughput. Comprehensive control/evaluation software for the recognizer has been developed for the AT&T PC6300 personal computer.