Method and apparatus of rejecting false hypotheses in automatic speech recognizer systems

Claim 1

A method of improving the reliability of keyword identification by a speech recognition system for continuously spoken speech in a given language comprising the steps of: providing a set of keyword templates each of which represents a respective keyword for recognition by said system; providing a set of filler templates each of which is representative of an arbitrary sound or utterance that is a component of spoken speech including words in said given language; generating a set of signals indicative of said spoken speech in a given time interval; providing parallel operations of: (a) comparing said set of signals with said keyword templates and selecting the keyword template having the greatest statistical similarity to said set of signals in said given time interval; and generating a keyword match score indicative of the statistical distance of said selected keyword template from said set of signals; and (b) separately comparing said set of signals with said filler templates and selecting a concatenation of filler templates having the greatest statistical similarity to said set of signals in the same given time interval; and generating a filler concatenation match score indicative of the statistical distance of said conctenation of filler templates from said set of signals; and comparing the keyword match score to the filler concatenation match score to determine, according to a pre-established threshold, whether said keyword match score is sufficiently better than said filler concatenation match score to confirm keyword identification.

Claim 2

A method of improving the reliability of keyword identification by a speech recognition system for continuously spoken speech in a given language comprising the steps of: providing a set of keyword templates each of which represents a respective keyword for recognition by said system; providing a set of filler templates each of which is representative of an arbitrary sound or utterance that is a component of spoken speech including words in said given language; generating a set of signals indicative of said spoken speech in a given time interval; providing parallel operations of: (a) comparing said set of signals with said keyword templates and selecting the keyword template having the greatest statistical similarity to said set of signals in said given time interval; and generating a keyword match score indicative of the statistical distance of said selected keyword template from said set of signals; and (b) separately comparing said set of signals with said filler templates and selecting a concatenation of filler templates having the greatest statistical similarity to said set of signals in the same given time interval; and generating a filler concatenation match score indicative of the statistical distance of said conctenation of filler templates from said set of signals; and comparing the keyword match score to the filler concatenation match score to determine, according to a pre-established threshold, whether said keyword match score is sufficiently better than said filler concatenation match score to confirm keyword identification.

Claim 3

A method of detecting keywords in continuously spoken speech comprising: generating a series of speech samples from said spoken speech for a given time interval; comparing said samples in said given time interval to a set of keyword templates each of which represents a respective keyword and selecting one of said keyword templates as a best keyword match for said speech samples; generating a keyword match score indicative of the degree of matching of said samples in said given time interval to said selected keyword template; separately comparing said samples to a set of filler templates, each filler template corresponding to an arbitrary sound or utterance that is a component of spoken speech including words, and selecting a concatenation of said filler templates as a best filler concatenation match for said samples in the same given time interval; generating a filler concatenation match score indicative of the degree of matching of said samples in said given time interval to said filler concatenation; and comparing said keyword match score to said filler concatenation match score to confirm that said keyword match score exceeds said filler concatenation match score by a predetermined threshold to confirm keyword detection.

Claim 4

A method of detecting keywords in continuously spoken speech comprising: generating a series of speech samples from said spoken speech for a given time interval; comparing said samples in said given time interval to a set of keyword templates each of which represents a respective keyword and selecting one of said keyword templates as a best keyword match for said speech samples; generating a keyword match score indicative of the degree of matching of said samples in said given time interval to said selected keyword template; separately comparing said samples to a set of filler templates, each filler template corresponding to an arbitrary sound or utterance that is a component of spoken speech including words, and selecting a concatenation of said filler templates as a best filler concatenation match for said samples in the same given time interval; generating a filler concatenation match score indicative of the degree of matching of said samples in said given time interval to said filler concatenation; and comparing said keyword match score to said filler concatenation match score to confirm that said keyword match score exceeds said filler concatenation match score by a predetermined threshold to confirm keyword detection.