1. A method to determine whether a presentation device is ON or OFF, the method comprising: determining an audio signature based on an audio signal corresponding to an output of the presentation device; comparing the audio signature to a set of reference signatures corresponding to a set of known media content; and determining a result indicating whether the presentation device is ON or OFF based on whether the audio signature matches any of the set of reference signatures, wherein the result is a first result, and the method further comprises: determining a second result indicating whether the presentation device is ON or OFF based on whether an audio gain level used to adjust the audio signal prior to determining the audio signature exceeds a threshold, wherein the second result indicates that the presentation device is ON when the audio gain level does not exceed the threshold, and the second result indicates that the presentation device is OFF when the audio gain level exceeds the threshold; and combining the first result and the second result to determine an overall result indicating whether the presentation device is ON or OFF.