Abstract: A speech recognition method and apparatus for detecting and recognizing one or more keywords in a continuous audio signal are disclosed. Each keyword is represented by a keyword template which corresponds to a sequence of plural target patterns, and each target pattern comprises statistics representing each of a plurality of spectra selected from plural short-term spectra generated according to a predetermined system for processing the incoming audio. The target patterns also have associated therewith minimum and maximum dwell times. The dwell time is the time interval during which a given target pattern can be said to match incoming frame patterns. The spectra are processed to enhance the separation between the spectral pattern classes during later analysis. The processed audio spectra are grouped into multi-frame spectral patterns and each multi-frame spectral pattern is compared by means of likelihood statistics with the target patterns of keyword templates.

Abstract: A speech recognition method and apparatus for recognizing word strings in a continuous audio signal are disclosed. The word strings are made up of a plurality of elements, and each element, generally a word, is represented by an element template defined by a plurality of target patterns. Each target pattern is represented by a plurality of statistics describing the expected behavior of a group of spectra selected from plural short-term spectra generated by processing of the incoming audio. Each target pattern has associated therewith at least one required dwell time position and at least one optional dwell time position. The number of required dwell time positions and the sum of the required and optional dwell time positions define, in effect, the limits of a time interval during which a given target pattern can be said to match an incoming sequence of frame patterns. The incoming audio spectra are processed to enhance the separation between the spectral pattern classes during later analysis.

Abstract: An improved speech recognition method and apparatus for recognizing keywords in a continuous audio signal are disclosed. The keywords, generally either a word or a string of words, are each represented by an element template defined by a plurality of target patterns. Each target pattern is represented by a plurality of statistics describing the expected behavior of a group of spectra selected from plural short-term spectra generated by processing of the incoming audio. The incoming audio spectra are processed to enhance the separation between the spectral pattern classes during later analysis. The processed audio spectra are grouped into multi-frame spectral patterns and are compared, using likelihood statistics, with the target patterns of the element templates. Each multi-frame pattern is forced to contribute to each of a plurality of pattern scores as represented by the element templates.