Patent 9148742 was granted and assigned to Google on September, 2015 by the United States Patent and Trademark Office.
Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for detecting ambient audio, generating audio data based on the ambient audio, generating a first audio fingerprint based on the audio data, providing the first audio fingerprint to a fingerprint comparison engine, the fingerprint comparison engine providing a comparison between the first audio fingerprint and a second audio fingerprint, and receiving a proximity signal based on the comparison.