Correction of quasiphoneme strings by the dynamically expanding context

An attempt is described to improve the overall accuracy of a phoneme-based speech recognizer using a grammar that corrects error in the so-called quasiphoneme strings. These strings result when speech frames are independently labeled to phonemic classes every hundredth of a second. A syntactic symbol string-correction method, the dynamically expanding context, is then applied. The method involves a large set of context-sensitive rules that describe the errors and coarticulation effects in the quasiphoneme strings and are constructed automatically from examples. This rule set is then able to cancel errors that have similar morphology. The overall accuracy of phonemic speech recognition can be increased by 1.5% to 8% over that achievable by other means