1. A method comprising: receiving, from a first classifier, a first voice activity indicator detected in a first modality for a human subject; receiving, from a second classifier, a second voice activity indicator detected in a second modality for the human subject, wherein the first voice activity indicator and the second voice activity indicators are based on the human subject at a same time, and wherein the first modality and the second modality are different; concatenating, via a third classifier, the first voice activity indicator and the second voice activity indicator with original features of the human subject, to yield a classifier output; and determining voice activity based on the classifier output.