Patent ID: 6665411
Filing Date: 2003-12-16
Classification: G10K,H04R

Abstract:
A digital voice enhancement communication system comprising:a first acoustic zone; a second acoustic zone; a microphone at said first zone; a loudspeaker at said second zone and electrically coupled to said microphone such that the speech of a person at said first zone can be heard by a person at said second zone as transmitted by an electrical signal from said microphone to said loudspeaker, said loudspeaker being acoustically coupled to said microphone such that said microphone is subject to acoustic feedback from said loudspeaker; an instability detector detecting an unstable acoustic feedback condition from said loudspeaker to said microphone by sensing a condition of said electrical signal transmitted from said microphone to said loudspeaker; a corrective processor responsive to said instability detector to modify said electrical signal to reduce unstable acoustic feedback, wherein said sensed condition is a sinusoidal characteristic of said electrical signal wherein said sensed condition is said electrical signal becoming sinusoidal in nature, and wherein said instability detector comprises: a model modeling said electrical signal as a filter model with filter coefficients; detection logic monitoring one of said filter coefficients and outputting a feedback indicator signal to said corrective processor in response to a given condition of said filter coefficient, wherein said detection logic outputs said feedback indicator signal to said corrective processor when the variation of said filter coefficient is below a designated threshold, and wherein said detection logic outputs said feedback indicator signal to said corrective processor when the magnitude of the variation of said filter coefficient is below said designated threshold.