SPEECH RECOGNIZER FOR YOICE CONTROL OF MOBILE TELEPHONE

Infovox is mqltetlng a speaker-dependent, pattem-matching word recognition system, developed at KTII. The algorithms in the system have been-modified foi noise im-munity, and performance has been evaluated in moving cars. The mainproblems were word detection and noise compensation. After simulaoons we decided to use a close-talking microphone and a "noise additionu method, where we added the measured nois-e in tle moving car to the reference pattems recorded in a parked car. Using this method, the recognition rate was improved fron 697o to 97Vo on a ten-word voiabu-lary using the best microphone. A more extensive test was performed on the modified recognition system using two cars and twelve speakers, seven male and five female. Most of them were naive speakers. The twenty-word vocabulary contained some con-fusable words and was trained in a parted car. During 98 sessions, 1,960 words were read under different conditions with an average recognition rute of.867o. With closed windows at 90 kn/h the mean was9l%o. An open window at the same speed decreased theresult to82Vo