  A microphone array can provide a mobile robot with the capability of
localizing, tracking and separating distant sound sources in 2D, i.e.,
estimating their relative elevation and azimuth. To combine acoustic data with
visual information in real world settings, spatial correlation must be
established. The approach explored in this paper consists of having two robots,
each equipped with a microphone array, localizing themselves in a shared
reference map using SLAM. Based on their locations, data from the microphone
arrays are used to triangulate in 3D the location of a sound source in relation
to the same map. This strategy results in a novel cooperative sound mapping
approach using mobile microphone arrays. Trials are conducted using two mobile
robots localizing a static or a moving sound source to examine in which
conditions this is possible. Results suggest that errors under 0.3 m are
observed when the relative angle between the two robots are above 30 degrees
for a static sound source, while errors under 0.3 m for angles between 40
degrees and 140 degrees are observed with a moving sound source.
