Microphone array beamforming based on maximization of the front-to-back ratio

Abstract

Microphone arrays are typically used in room acoustic environments to acquire high fidelity audio and speech signals while suppressing noise, interference, and reverberation. In many application scenarios, interference and reverberation may mainly come from a certain region, and it is therefore necessary to develop beamformers that can preserve signals of interest while minimizing the power of signals coming from the region where interference and reverberation dominate. For this purpose, this paper first reexamines the so-called front-to-back ratio and the classical supercardioid beamformer. To deal with the white noise amplification problem and the limited directivity factor associated with the supercardioid beamformer, a set of reduced-rank beamformers are deduced by using the well-known joint diagonalization technique, which can make compromises between the frontto-back ratio and the amount of white noise amplification or the directivity factor. Then, the definition of the front-to-back ratio is extended to a generalized version, from which another set of reduced-rank beamformers and their regularized versions are developed. Simulations are conducted to illustrate the properties and advantages of the proposed beamformers.

Design of Planar Differential Microphone Array Beampatterns with Controllable Mainlobe Beamwidth and Sidelobe Level

“…Again, the order of the Chebyshev polynomial is set to be , and (dB) is taken, i.e., the desired beampattern that we want to approximate is Figure 2 d. So, microphones are needed. The radius of the UCA is set to be m. The beampatterns of the null-constrained beamformer with different frequencies ( and 4000 Hz) are shown in Figure 4 , including the beampattern of the maximum front-to-back ratio [ 63 ] (purple dot line) beamformer at Hz. We can see from Figure 4 that, at relatively low frequencies, the beampattern of the null-constrained beamformer is very close to the desired one.…”