A speech system recognizes words from a spoken phrase that conform to checksum constraints. Grammar rules (30) are applied to hypothesize words (24) according to the checksum constraints. The checksum associated with the phrase is thus inherent in the grammar. Sentences which do not meet a predetermined checksum constraint are not valid under the grammar rules and are therefore inherently rejected (34). The checksum constraints result in increased recognition accuracy. <IMAGE>
Grammar-based checksum constraints for high performance speech recognition circuit