There is precedent for echolocation in the natural world: bats can navigate based on the echo of their chirrups; and blind humans, at least anecdotally, sometimes develop remarkable sound-based spatial skills. But using sound to accurately map a space in three dimensions? That’s new.
This week, scientists at the École Polytechnique Fédérale, in Lausanne, in Switzerland, published a study showing how a newly developed algorithm uses sound to measure the dimensions of a space. Their system only requires four standard microphones -- placed anywhere in any space -- and a sound as small as a finger snap to generate a model. It’s a bit like the spatial triangulation used by 3D scanners -- except this system uses sound, rather than light. A PhD student at EPFL named Ivan Dokmanić explains:
“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 not only the distance between the microphones, but also the distance from each microphone to the walls and the sound source.”
The group began by testing the system in a six-sided room, but went on to accurately map part of the ornate Lausanne Cathedral, the 900-year-old church in the heart of city. The study -- which appeared in The Proceedings of the National Academy of Sciences -- only presents the team’s initial research, which they plan to continue with over the next few years.
But that hasn’t stopped the team from speculating about how the technology could be applied. According to Dokmanić, architects could eventually use the algorithm to get accurate measurements of a particular building or site. Likewise, acoustical engineers could use it to create amphitheatres whose shapes are based on an ideal sound. There are also plenty of more world-changing uses: 000 operators could determine what type of room a caller is in. At the same time, as with all powerful technology, it's possible to imagine this kind of system being used for more sinister purposes. Either way, it’s a fascinating piece of research -- check out the report here.