Design of broad-band circular ring microphone array for speech acquisition in 3-D

In this paper we address the problem of speech acquisition using a concentric circular ring array with omnidirectional microphones. The goal of our design is to achieve a specified sidelobe level in the beam pattern. A previous work by Stearns et al. (1965) proposed a method to achieve low sidelobe level for a continuous concentric ring antenna. The method assumes a narrowband signal and uses continuous ring and therefore is not suitable for speech application. This paper generalizes Stearns´ method to broadband signal acquisition in 3D using a discrete ring array. A compound ring structure is employed to reduce the number of rings involved. An example is given to demonstrate our design method. The proposed design method can be used to produce a nonadaptive beamformer with a certain desirable beam pattern, or to generate the weight constraint corresponding to the white-noise beam pattern in an adaptive beamformer.