Patent ID: 6285768
Filing Date: 2001-09-04
Classification: H03H

Abstract:
A noise canceling method for receiving a reference noise signal from a reference input terminal for input into a first adaptive filter and generating a pseudo noise signal through filtering according to filter coefficients, for subtracting, through a subtracter, the pseudo noise signal from a received-signal to generate an error signal, said received-signal being composed of a speech signal and a background signal entered from a speech input terminal, and for serially modifying the filter coefficients of said first adaptive filter in response to the error signal to output from said subtracter said received-signal from which noises are removed, said noise canceling method comprising the steps of:receiving said reference signal and said received-signal;detecting an error signal power and a pseudo noise signal power from the pseudo noise signal generated by a second adaptive filter with a configuration similar to the configuration of said first adaptive filter;estimating a signal-to-noise power ratio of said received-signal from the error signal power and pseudo noise signal power;adaptively changing the filter coefficients of said second adaptive filter with a value corresponding to an average signal-to-noise power ratio calculated by averaging the signal-to-noise power ratios as a filter coefficient modification amount;comparing the estimated value of said signal-to-noise power ratio with the delayed estimated value produced by delaying the estimated value of said signal-to-noise power ratio for a predetermined time and outputting the larger as the estimated value of an extended signal-to-noise power ratio; andadaptively changing the filter coefficients with the value corresponding to the estimated value of the extended signal-to-noise power ratio as the modification amount of the filter coefficients of said first adaptive filter.