A computerized machine (a) determines temporal and spatial confidence intervals for each one of plural sonic events, (b) classifies pairings among the sonic events as either comparable or non-comparable, and (c) estimates a minimum number of sonic sources, some of which are in motion, that could have produced or generated the sonic events. Sonic event times and positions are characterized by corresponding temporal and spatial confidence intervals. A pairing of sonic events is classified as comparable only when that pairing meets one or more preselected constraints, some of which depend on the temporal and spatial confidence intervals. The estimated minimum number of sonic sources is equal to the total number of sonic events minus the cardinality of a maximum matching of a bipartite graph derived from the classifications of the pairings and a chronological ordering of the set of sonic events.