A speech recognition apparatus is adapted to previously prepare a noise pattern in response to environmental noise prior to inputting a speech signal, evaluate a speech feature vector B.sub.i yielded by subtracting the noise pattern from a feature vector A.sub.i of the input speech upon inputting the...http://www.google.com.au/patents/US4918735?utm_source=gb-gplus-sharePatent US4918735 - Speech recognition apparatus for recognizing the category of an input speech pattern
