Mixed nearfield/farfield beamforming: a new technique for speech acquisition in a reverberant environment

In designing a microphone array for speech acquisition in a reverberant room, one is often faced with a mixed nearfield/farfield design problem, i.e., design a beamformer which can focus on a nearfield source, but which simultaneously can cancel room reverberation (which is typically modeled as isotropic farfield interference). This paper presents a new technique to solve such a problem. Using the spherical solution to the wave equation, a beamforming technique is presented to simultaneously approximate a desired nearfield beampattern and a desired farfield beampattern.