Noise reduction method for wideband speech coding

We present a new low complexity noise reduction (NR) method based on spectral subtraction and overlap-add analysis/synthesis. A voicing dependent cut-off frequency is introduced, dividing the speech spectrum into two parts. In lower end, the NR gain function varies with frequency bins to minimize distortion at pitch harmonic frequencies while maximizing the suppression between them. In higher end, the gain function is estimated per critical band reducing energy variations. The gain function is further smoothed over time with a smoothing factor adaptive with the actual NR gain to prevent distortion on voiced speech onsets. The NR is as a part of VMR-WB speech codec recently selected as a new 3GPP2 standard for wideband speech applications in cdma2000 3G wireless system.