Two-microphone subband noise reduction scheme with a new noise subtraction parameter for speech quality enhancement

An improved subband noise reduction technique is proposed for two-microphone voice communication systems. The technique aims to enhance the speech quality by utilising a subband structure with different noise reduction schemes for different frequency bands. In the low-frequency band where dominant cues of speech spectral components are usually located and the noise signals from the two channels are mainly correlated, the spectral subtraction method, together with a new variable noise subtraction parameter, is employed so that the noise attenuation performance and speech distortion are controllable. In the high-frequency band where less-dominant frequency information of speech spectrum is located, the modified cross-spectral subtraction technique is utilised to remove the high-frequency decorrelated noise spectral components. Extensive comparisons among various noise reduction techniques based on computer simulations demonstrate that the proposed two-microphone subband noise reduction scheme achieves excellent noise attenuation performance while preserving the speech quality.