Reference-free audio matching for rendezvous

We consider the problem of efficiently determining whether two microphones are listening to the same acoustic signal. This “reference free” acoustic match problem is useful, for example, for allowing networked computers or phones to automatically rendezvous and collaborate whenever they are within earshot. We describe how this problem differs from the well-studied music identification problem. We cast the problem as a hypothesis test, and argue that an effective test statistic may be found using frequency-domain inner products. We validate our approach using a set of 75 speech samples together with inexpensive microphones built in to notebook computers.