Invisibilité acoustique

Kind of "invisibility cloak". The acoustic cloak developed by these researchers contains 120 aluminium cylinders 15 mm in diameter, surrounding a 22.5 cm cylinder. The position of each cylinder in the cloak has been obtained by using optimization techniques based on genetic algorithms (numerical algorithms which mimic Darwinian evolution).
http://www.uv.es/uvweb/college/en/news-release/first-experimental-tridimensional-device-acoustic-invisibility-has-been-designed-1285846070123/Noticia.html?id=1285875404982