1. One or more computer-readable media storing instructions that, when executed by a computing device having a processor, perform a method of separating audio sources in a multi-microphone system, the method comprising: receiving audio sample groups, with an audio sample group comprising at least two samples of audio information, the at least two samples captured by different microphones during a sample group time interval; and for a plurality of audio sample groups: estimating, for the corresponding sample group time interval, an angle between a first reference line extending from an audio source to the multi-microphone system and a second reference line extending through the multi-microphone system, the estimated angle being based on a phase difference between the at least two samples in the audio sample group; modeling the estimated angle as a combined statistical distribution, the combined statistical distribution being a mixture of a target audio signal statistical distribution and a noise component statistical distribution; and determining whether the audio sample group is part of a target audio signal or a noise component based at least in part on the combined statistical distribution.