Karim Helwani has presented a paper at the Asilomar Conference on Signals, Systems, and Computers on beamforming algorithms for microphone arrays with acoustically rigid surfaces. Principles from Wave Field Synthesis and time-reversal acoustics are used to derive computationally efficient and robust delay-and-sum algorithms.
K. Helwani, S. Spors, and H. Buchner. How to implement a delay and sum beamforming
for rigid rotational symmetric arrays? In Asilomar Conference on Signals,
Systems, and Computers, Pacific Grove, USA, November 2012.
Resulting beampatterns for a 25 elements rigid cylindrical microphone array
Abstract — In this paper we present two novel techniques with low computational complexity and high robustness for beamforming using rigid microphone arrays. For the first one we show which approximations have to be made in terms of applying techniques that are equivalent to delay-and-sum beamforming on rigid microphone arrays. In the second approach we exploit the technique of focused sinks for creating virtual linear microphone arrays with flexible dimensions and spacing. As a result, simple techniques for beamforming using linear arrays can be applied. We derive our approaches analytically, state their theoretical limits and provide simulation results and discuss the results.