A directivity based reference for the multichannel Wiener filter
* Presenting author
The multichannel Wiener filter (MWF) is a well-established multichannel noise reduction technique which takes the spatial sound field into account. The decomposition of the MWF shows, that the overall transfer function from the mouth reference point of a speech source to the output of the algorithm equals an acoustic transfer function which depends on the selection of a dedicated microphone reference channel. It was shown in more recent publications, that the reference can be designed by combining the individual channels in an appropriate manner. For spatially distributed microphones, suitable reference selections were already presented which show an improvement in the signal-to-noise ratio (SNR) as well as the log spectral distance (LSD). In our work, a class of directivity based references for the MWF is introduced which is suitable for closely spaced microphone arrangements. The proposed references are based on differential microphone processing approaches to form spatial filtering in terms of dipole, cardioid and hyper cardioid beam patterns. Simulations are performed for hearing aids with closely spaced microphones in a cylindrical isotropic noise field and a cafeteria environment. The results show a superior performance regarding the SNR improvement as well as a reduced LSD compared with other MWF references.