Patent ID: 6633842
Filing Date: 2003-10-14
Classification: G10L

Abstract:
A method of speech recognition operating under noisy conditions comprising:producing an estimated clean feature vector from a noisy feature vector comprising the steps for each frame of: (a) calculating estimate of noise power spectrum {tilde over (&mgr;)}P as an average over a set of frames, (b) calculating noisy space &mgr;i&PSgr;,P of the noisy mixture density, (c) for every frame (1) sampling input speech to produce frames; (2) generating a noisy feature vector for each frame; (3) calculating log PY(y|&agr;i) where PY (y|ai) is the likelihood of observing y in given mixture component of ai for all mixture components, and (4) calculate clean vector estimate according to: x^=&Sum;i&Element;[1,N],log&it;â€ƒ&it;pY&it;â€ƒ&it;(y|ai)>Î¸â€ƒ&it;â€ƒ&it;Î¼iÏ‡&it;â€ƒ&it;exp&af;[Î±&it;â€ƒ&it;(log&it;â€ƒ&it;pY&it;â€ƒ&it;(y|ai)+log&it;â€ƒ&it;Pr&it;â€ƒ&it;(ai))]&Sum;i&Element;[1,N],log&it;â€ƒ&it;pY&it;â€ƒ&it;(y|ai)>Î¸â€ƒ&it;â€ƒ&it;exp&af;[Î±&it;â€ƒ&it;(log&it;â€ƒ&it;pY&it;â€ƒ&it;(y|ai)+log&it;â€ƒ&it;Pr&it;â€ƒ&it;(ai))];andapplying said clean vector estimate to a speech recognizer for providing recognized speech.