At EPFL, a team from the Audiovisual Communications Laboratory (LCAV), under the direction of Professor Martin Vetterli developed the computer algorithm.
PhD student Ivan Dokmanic said that their software can build a 3D map of a simple, convex room with a precision of a few millimeters.
Dokmanic said that the microphones don't need to be placed carefully.
He said that each mic picks up the direct sound from the source, as well as the echoes arriving from various walls.
He asserted that the algorithm then compares the signal from each mic and the infinitesimal lags that appear in the signals are used to calculate not only the distance between the microphones, but also the distance from each microphone to the walls and the sound source.
This ability to "sort out" the various echoes picked up by the microphones is in itself a first.
By analyzing each echo's signal using "Euclidean distance matrices," the system can tell whether the echo is rebounding for the first or second time, and determine the unique "signature" of each of the walls.
It may also be possible to implement this algorithm in mobile devices and use them to deduce location information inside buildings - a place where GPS signals do not penetrate well.
The experiment will soon be published in the Proceedings of the National Academy of Sciences.
--ANI (Posted on 19-06-2013)