A hybrid approach to robust word lattice generation via acoustic-based word detection

A large-vocabulary continuous speech recognition (LVCSR) system usually utilizes a language model in order to reduce the complexity of the algorithm. However, the constraint also produces side-effects including low accuracy of the out-ofgrammar sentences and the error propagation of misrecognized words. In order to compensate for the side-effects of the language model, this paper proposes a novel lattice generation method that adopts the idea from the keyword detection method. By combining the word candidates detected mainly from the acoustic aspect of the signal to the word lattice from the ordinary speech recognizer, a hybrid lattice is constructed. The hybrid lattice shows 33% improvement in terms of the lattice accuracy under the condition where the lattice density is the same. In addition, it is observed that the proposed model shows less sensitivity to the out-of-grammar sentences and to the error propagation due to misrecognized words.