Parallel beamformer design under response equalization constraints

In some applications, it may be desirable to design a certain number of fixed beamformers that have different look directions but the same response to a certain predetermined signal, referred to as the equalization signal. In this article we present a method to accomplish this task, and show that it is optimal for a natural directivity criterion. We then demonstrate the effectiveness of this method with an application to an audio conference telephone where the equalization signal is the direct-path loudspeaker coupling signal.