An automatic content recognition system that includes a user device for the purpose of capturing audio and generating an audio signature. The user device may be a smartphone or tablet. The system is also capable of determining whether a user device is in motion and refraining from audio monitoring and/or generating audio signatures when the user device is in motion. Motion may also be used to reduce the frequency of audio monitoring and/or signature generation. The system may have a database within the user device or the user device may communicate with a server having a database that contains reference audio signatures.