Analysis of localization cue preservation by multichannel wiener filtering based binaural noise reduction in hearing aids

In this paper the localization cue preservation of a noise reduction algorithm for binaural hearing aids is analyzed. In a binaural noise reduction procedure based on Multi-channel Wiener Filtering (MWF), the basic cost function is extended with terms related to the Interaural Transfer Functions (ITF) of a speech and noise source. To make the algorithm computationally feasible, these cost terms are simplified to quadratic terms. First it is shown that this approach cannot preserve the ITF of the speech and noise component simultaneously. However, the obtained output ITF is related to the output SNR. This will lead to a perceptually advantageous effect: a noisy output signal (low SNR) will be perceived in the direction of the noise source, while a clean output signal (high SNR) will be perceived in the direction of the speech source.