Method and apparatus for accurate endpointing of speech in the presence of noise

A method of detecting endpoints of an utterance in frames of a received signal, comprising the steps of:

• comparing an utterance with a first threshold value to determine a first starting point and a first ending point of the utterance;
• comparing with a second threshold value a part of the utterance that predates the first starting point to determine a second starting point of the utterance;
• and
• comparing with the second threshold value a part of the utterance that postdates the first ending point to determine a second ending point of the utterance, wherein the first and second threshold values are calculated once per frame from a signal-to-noise ratio for the utterance.

A device for detecting endpoints of an utterance in frames of a received signal, comprising:

• means for comparing an utterance with a first threshold value to determine a first starting point and a first ending point of the utterance;
• means for comparing with a second threshold value a part of the utterance that predates the first starting point to determine a second starting point of the utterance;
• and
• means for comparing with the second threshold value a part of the utterance that postdates the first ending point to determine a second ending point of the utterance, wherein the first and second threshold values are calculated once per frame from a signal-to-noise ratio for the utterance.

A voice recognition system, comprising:

• an acoustic processor configured to determine parameters of an utterance contained in received frames of a speech signal, the acoustic processor including an endpoint detector configured to compare the utterance with a first threshold value to determine a first starting point and a first ending point of the utterance, compare with a second threshold value a part of the utterance that predates the first starting point to determine a second starting point of the utterance, and compare with the second threshold value a part of the utterance that postdates the first ending point to determine a second ending point of the utterance, wherein the first and second threshold values are calculated once per frame from a signal-to-noise ratio for the utterance;
• pattern comparison logic coupled to the acoustic processor and configured to compare stored word templates with parameters associated with the utterance;
• and
• a database coupled to the pattern comparison logic and configured to store the word templates.