Method and apparatus for locating a talker

Abstract

An apparatus for locating a talker, comprising a microphone array for receiving multiple audio signals, wherein the microphone array is characterized by a predetermined beampattern, a spectral conditioner for filtering the audio signals to optimize the beampattern for talker localization, a localization estimator for calculating a localization estimate based on the filtered audio signals, an activity detector for detecting periods of speech activity, and decision logic for verifying the localization estimate during the periods of speech activity.

1 . A method of locating a talker, comprising the steps of: 
 receiving multiple audio signals from a microphone array characterized by a predetermined beampattern;    filtering said audio signals to optimize said predetermined beampattern for talker location;    detecting periods of speech activity;    calculating a localization estimate based on the filtered audio signals;    discarding said localization estimate if calculated during a period where there is no speech activity; and    verifying said localization estimate during said periods of speech activity.    
     
     
         2 . The method of  claim 1 , wherein said step of filtering comprises subjecting said audio signals to bandpass filtering at a center frequency of 1150 Hz and a bandwidth of 300 Hz.  
     
     
         3 . The method of  claim 1 , wherein said step of verifying further includes storing a succession of localization estimates, counting occurrences of said localization estimates during said periods of speech activity and within a predetermined sample window and selecting any one of said occurrences which is repeated more than a predetermined threshold number of times within said window.  
     
     
         4 . The method of  claim 3 , wherein said predetermined threshold number is 12 and said predetermined sample window is 32 estimates.  
     
     
         5 . An apparatus for locating a talker, comprising; 
 a microphone array for receiving multiple audio signals, said a microphone array being characterized by a predetermined beampattern;    a spectral conditioner for filtering said audio signals to optimize said predetermined beampattern for talker localization;    a localization estimator for calculating a localization estimate based on the filtered audio signals;    an activity detector for detecting periods of speech activity; and    decision logic for discarding each localization estimate if calculated during periods where there is no speech activity and for verifying said localization estimate during said periods of speech activity.    
     
     
         6 . The apparatus of  claim 5 , wherein said spectral conditioner comprises a bandpass filter for filtering said audio signals at a center frequency of 1150 Hz and a bandwidth of 300 Hz.  
     
     
         7 . The apparatus of  claim 5 , wherein said decision logic further includes a memory stack for storing up to a predetermined number of localization estimates, a counter for counting occurrences of said localization estimates during said periods of speech activity and selecting any one of said occurrences which is repeated more than a predetermined threshold number of times within said memory stack.  
     
     
         8 . The apparatus of  claim 7 , wherein said predetermined threshold number is 12 and said predetermined number of localization estimates within said stack is 32.  
     
     
         9 . A bandpass filter when used in a system for locating a talker, the system comprising a talker localization estimator which receives multiple audio signals from a microphone array characterized by a predetermined beam pattern and in response generates a location estimate of a talker relative to said array from localization estimates calculated during periods of speech activity, wherein estimates generated during periods where there is no speech activity are discarded, said bandpass filter filtering said audio signals to optimize said predetermined beam pattern for talker localization.  
     
     
         10 . The bandpass filter of  claim 9 , characterized by a center frequency of 1150 Hz and a bandwidth of 300 Hz.  
     
     
         11 . A method of generating talker location estimates comprising the steps of: 
 bandpass filtering audio signals to enhance the beam pattern thereof for talker localization prior to conveying the audio signals to a location estimator; and    generating a first order position estimates in response to the filtered audio signals;    detecting periods of speech activity; and    discarding estimates generated during periods where there is no speech activity.