  This paper proposes an efficient method based on the steered-response power
(SRP) technique for sound source localization using microphone arrays: the
volumetric SRP (V-SRP). As compared to the SRP, by deploying a sparser
volumetric grid, the V-SRP achieves a significant reduction of the
computational complexity without sacrificing the accuracy of the location
estimates. By appending a fine search step to the V-SRP, its refined version
(RV-SRP) improves on the compromise between complexity and accuracy.
Experiments conducted in both simulated- and real-data scenarios demonstrate
the benefits of the proposed approaches. Specifically, the RV-SRP is shown to
outperform the SRP in accuracy at a computational cost of about ten times
lower.
