Abstract:

A new method of designing a beamformer having a desired near-field beampattern is presented. Although a plethora of techniques have been proposed for far-field beamformer design (where the received wavefronts are planar), these methods generally result in severe beampattern degradation when used in a near-field environment (when the source is sufficiently close to the array that the spherical nature of the wavefronts must be taken into account). In this paper a computationally simple design procedure is presented in which established far-field design techniques can be employed to achieve near-field beampatterns with high accuracy. The theoretical underpinnings of this procedure are based on the spherical solution to the wave equation. The method can be applied to the problem of designing a microphone array for speech acquisition from a near-field talker.