| 摘要 |
PROBLEM TO BE SOLVED: To improve a noise elimination amount and to reduce a distortion (residual error) by deciding a step size of an adaptive filter based on both values of a signal/noise power ratio and its mean value. SOLUTION: An SNR mean circuit 21 for calculating a time mean of the signal/noise power ratio is provided. A subtraction circuit 16 subtracts output voice signal power of a power mean circuit 14 with output noise signal power of the power mean circuit 15 to output the estimated value SNR1 of the signal/ noise power ratio as the result. The SNR mean circuit 21 receives the estimated SNR value SNR1 outputted from the subtraction circuit 16 to calculate its mean value SNR4. A step size output circuit 20 receives the SNR mean value SNR4 outputted from the SNR mean circuit 21 and an extended signal/noise power ratio SNR4 outputted from a comparison circuit 18 to output the step size of the adaptive filter 4. In such a manner, the step size is decided using the value of the SNR4 being the mean SNR value not only the value of the SNR3. |
