Closed-Form Solution to the Multichannel Wiener Filter With Interaural Level Difference Preservation

This article presents a multichannel Wiener filter (MWF) based noise reduction method with preservation of the interaural level difference (ILD). It minimizes the MWF cost function subject to two constraints for ILD preservation. Under this approach, the weighting coefficient that establishes the trade-off between noise reduction and binaural cue preservation takes a physical interpretation, facilitating its design. The proposed approach results in a convex optimization problem that admits a computationally efficient semi-analytical closed-form solution. Simulation experiments in hearing aid applications were performed considering practical acoustic scenarios. Considering an appropriate set of control parameters, the average performance of the proposed method preserves the ILD of a single interfering source in the same way as the conventional MWF-ILD, keeping the same level of noise reduction as the classic MWF, with approximately the same amount of speech ILD distortion. The proposed method is particularly interesting for implementing real-time noise reduction methods in binaural hearing aids.