Single-chip speech recognition system based on 8051 microcontroller core

This paper describes a single-chip speech recognition system. It contains the speech functions of prompt, playback, speaker-dependent speech recognition, suitable for the voice activated systems in toys, games, consumer electronics, office devices, etc. The chip is designed based on the SOC (system on chip) philosophy and an 8-bit MCU, RAM, ROM, ADC/DAC, PWM, I/O ports and other peripheral circuits are all embedded in it. Software modules including control/communication, speech coding and speech recognition algorithms are implemented in an 8051 compatible microcontroller core, resulting in the extremely low cost of the chip. The speech recognition adopts the template matching technique. It recognizes up to 20 phrases with an average length of 1 second and the recognition accuracy reaches more than 95% with the background SNR above 10 dB. Speech coding uses continuous variable slope delta modulation (CVSD) algorithm. The bit rate is 16 kbits/s.