Low Latency Two Stage Beamforming with Distributed Microphone Arrays Using a Planewave Decomposition

Many rooms are equipped with conferencing systems with a large number of microphones. However, these systems are often limited to a fixed number of delay-and-sum beamformers and typical automix software will pick the beamformer output with the most energy. A more constructive combination is possible if we have access to the output of multiple beams constructed by such commercial systems. This article proposes a beamspace projection that may effectively view such a commercial conferencing system as a low-latency dimensionality reduction operation. Such a projection can be formulated as a plane wave decomposition of the received signals. Experiments conducted in simulation show that beamspace projection can rapidly approach the SINR gain achievable with access to all the microphones with lower computational complexity. Finally, we use commercial hardware and its beamformer outputs to separate numerous talkers in a real world environment.