Enhanced speaker activity detection for distributed microphones by exploitation of signal power ratio patterns

In cars with integrated distributed microphone systems usually each speaker has a dedicated microphone. An often required broadband speaker activity detection can be performed by simply evaluating the power ratios among the microphones but transient interferers like indicator noise, outside crossing cars or speech from interfering speakers may be wrongly assigned to one speaker´s activity. In this contribution a new method is presented that exploits patterns based on the characteristics of signal power inverted subbands at which compared to the closest microphone higher energy occurs in a distant one. By determination of a distance measure the currently observed pattern of these power inverted subbands is compared to online learned speaker position dependent reference patterns. During noise only periods as well as during transient interfering signals the patterns do not match the reference and false speaker activity detections can be reduced.