| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve sound quality in reducing noise by the spectral subtraction (SS) method.SOLUTION: A Fourier transform unit (202) subjects audio signals containing noise to Fourier transform. A noise profile memory (203) stores noise profiles indicating frequency amplitude contents of the noise. A divider (204) divides the output of the Fourier transform means by a noise profile for each frequency component. A variation-over-time control unit (205) smoothens the output of the divider (204), and a subtraction coefficient calculating unit (206) calculates subtraction coefficients that become smaller as the output of the variation-over-time control unit (205) becomes larger. A multiplier (207) multiplies each noise profile by a subtraction coefficient. A noise reducer (208) subtracts the output of the multiplier (207) from the output of the Fourier transform unit (202). An inverse Fourier transform unit (209) subjects the output of the noise reducer (208) to inverse Fourier transform.</p> |
