Researchers in Switzerland have developed an algorithm to measure the dimensions and shapes of a room using just four microphones and a sound. The software can build a 3-D map of a simple, convex room with a precision of a few millimeters. The microphones don’t need to be carefully placed. Each microphone picks up the direct sound from the source, as well as the echoes arriving from various walls. The algorithm then compares the signal from each microphone. The infinitesimal lags that appear in the signals are used to calculate the distance between the microphones and the distance from each microphone to the walls and the sound source. The ability to separate various echoes picked up by the microphones is 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.
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