Robust broadband regularized superdirective beamforming in the spherical harmonic domain

A robust broadband regularized superdirective beamformer which combines the superdirective beamformer and the delay-and-sum beamformer in the spherical harmonic domain is proposed.First,the analytic closed-form expression of the regularized superdirective beamformer is derived by controlling the white noise gain and the directivity factor.Then a new beamformer with the desired DF is designed so as to obtain an adequate WNG with realtive high DF for low frequencies.Simulation results with a 32-channel spherical array show that compared to the superdirective beamformer and the delay-and-sum beamformer,the proposed beamfomer can improve the highest PESQ score by 0.5 and0.4 and reduce the average WER by 9.5% and 8.1% respectively.In the directional noise and diffuse noise environments,the proposed beamfomer also shows better performnace in subjective listeing tests.The experimental results confirm the validity of the proposed method in real acoustic environments.