Fingerprint data derived from audio or other content is used as an identifier. The fingerprint data can be derived from the content. In one embodiment, fingerprint data supplied from two or more sources is aggregated. The aggregated fingerprint data is used to define a set of audio signals. An audio signal from the set of audio signals is selected based on its probability of matching the fingerprint data. Digital watermarks can also be similarly used to define a set of audio signals.