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March 21st, Ivan

Imagine that you are blindfolded inside an unknown room. You snap your fingers and listen to the room’s response. Can you hear the shape of the room? Some people can do it naturally, but can we design computer algorithms that hear rooms? We show how to compute the shape of a convex polyhedral room from its response to a known sound, recorded by a few microphones. Geometric relationships between the arrival times of echoes enable us to “blindfoldedly” estimate the room geometry. We achieve this by exploiting the properties of Euclidean distance matrices. Furthermore, we show that under mild conditions, first-order echoes provide a unique description of convex polyhedral rooms. Our algorithm starts from the recorded impulse responses and proceeds by learning the correct assignment of echoes to walls. The geometry of the microphone array is arbitrary, as well as the loudspeaker location: As long as the microphones can hear the echoes, we can position them as we want. In contrast to earlier methods, our proposed algorithm reconstructs the full three-dimensional geometry of the room from a single sound emission. Besides answering a basic question about the inverse problem of room acoustics, our results find applications in areas such as architectural acoustics, indoor localization, virtual reality and audio forensics.

https://blogs.epfl.ch/2013spring-lcavtam/documents/tam-spring-2013-can-one-hear-red.pdf

Posted by Runwei Zhang on Thursday 23 January 2014 at 13:10