A study into the design of steerable microphone arrays

The book covers the design formulations for broadband beamformer targeting nearfield and farfield sources. The book content includes background information on the acoustic environment, including propagation medium, the array geometries, signal models and basic beamformer designs. Subsequently it introduces design formulation for nearfield, farfield and mixed nearfield-farfield beamformers and extends the design formulation into electronically steerable beamformers. In addition, a robust formulation is introduced for all the designs mentioned

Performance Limit of Broadband Beamformer Designs in Space and Frequency

The design problem of broadband beamformers is to choose the coefficients of the filters such that the difference between the actual spatial directivity pattern and a desired spatial directivity pattern is minimized. There are many factors which can influence the performance of the design. The prominent factors include the filter length and the number of microphones. In the literature, the condition in fitting a desired spatial directivity pattern totally has not been studied properly. We show here that itis essential to use both the filter length and the number of sensors in reducing the cost function to zero, subject to some conditions on the desired response. These conditions are investigated and developed. Numerical examples are used to verify the derived conditions and at the same time to present some optimal beamformer designs