Optimizing the layout of multiple mobile robots for cooperative sound source separation

This paper presents a novel active audition method that enables multiple mobile robots to move to optimal positions for improving the performance of sound source separation. A main advantage of our distributed system is that each robot has its own microphone array and all mobile robots can collaborate on source separation by regarding a set of movable microphone arrays as a big reconfigurable array. To incrementally optimize the positions of the robots (the layout of the big microphone array) in an active-audition manner, it is necessary to predict the source separation performance from a possible layout of the next time step although true source signals are unknown. To solve this problem, our method simulates delay-and-sum beamforming from a possible layout for theoretically calculating the gain for each frequency component of a source signal in the corresponding separated signal. The robots are moved into a layout with the highest average gain over all sources and the whole frequency range. The experimental results showed that the harmonic mean of signal-to-distortion ratios (SDRs) was improved by 6.0 dB in simulations and by 5.7 dB in a real environment.