Cost-effective speech processing

Recent developments have made it possible to implement high performance speech recognition with much less computation than traditional techniques, thereby enabling real-time computation on standard microprocessors. Concepts such as time-domain acoustic-phonetic speech signal- processing as well as efficient adaptations of hidden Markov models can provide this type of capability. The Mark II system provides both speaker dependent and multiple speaker recognition of up to a 32 isolated word active vocabulary in real-time on a 2 MHz 6502, with no custom hardware, except an inexpensive microphone, pre-amp, and 8-bit A/D converter. On an initial test of 5120 test utterances (Texas Instruments isolated word data base, Spectrum, Sept., 1981), the Mark II achieved an error rate of only 0.67% (34 errors).