Example disclosed media source detection methods include determining first trending coefficients for a first audio signal obtained from a first media source in communication with a media device, wherein the first trending coefficients correspond to a set of frequency bands. Example disclosed media source detection methods also include determining second trending coefficients for a second audio signal obtained from monitoring media presented by the media device, wherein the second trending coefficients correspond to the set of frequency bands. Example disclosed media source detection methods further include selecting a subset of the frequency bands for which the first trending coefficients and the second trending coefficients have matching directions, and processing respective frequency band values of the first audio signal and respective frequency band values of the second audio signal for the subset of the frequency bands to determine whether the first media source provided the media presented by the media device.