Methods and apparatus for characterizing media are described. In one example, a method of characterizing media includes capturing a block of audio; converting at least a portion of the block of audio into a frequency domain representation; dividing the frequency domain representation into a plurality of bands; determining a characteristic difference of a first band of the plurality of bands based on a comparison of a characteristic of the first band and a characteristic of a second band different from the first band, wherein the characteristic of the first band occurs at a time that is different than a time at which the characteristic of the second band takes place; and determining a signature bit based on a characteristic difference. Other examples are shown and described.