In spontaneous speech, utterances are often ungrammatical and/or poorly modeled by conventional grammars, keyword spotting for detection of relevant words sequences could be ineffective and the recognition task cannot be improved. Therefore, a key-subword spotting strategy is proposed to catch in-word semantics on basis of a first stage recognition of an unknown word and thus both the speech recognition and the understanding tasks are facilitated by a second stage recognition of the same unknown word on basis of a vocabulary reduced according to the spotted key-subword.
Key-subword spotting for speech recognition and understanding