Patent US 4,882,757

Speech recognition is improved using prestored words and prestored sentences which provide grammar or context rules. Multiple word hypotheses and plural sentence hypotheses are used. A speech recognition system uses a word hypothesizer to generate hypothesized words for a sentence recognizer. The sentence recognizer receives information containing the hypothesized word and its beginning and end points. The sentence recognizer compares each incoming hypothesis with words allowed by a grammar, and generates a partial or complete sentence hypothesis for each state in which the hypothesis is allowed by the grammar. A dynamic programming technique using backpointer is used to retain all currently valid partial and complete sentence hypotheses. When a complete sentence satisfies suitable criteria, it is output as a recognized sentence. Gaps and overlaps between hypothesized words are used in calculation of a sentence error for each partial and complete sentence hypothesis.