Soon the acoustics will achieve what the optics has achieved: a material that diverts the waves as expected. To divert electromagnetic waves, such as light, metamaterials are used. There is no metamaterial for diverting sound waves, but it may be soon. Some American mathematicians have shown that theoretically it is possible to produce such special materials. If they did, the objects of this material would divert around the sound waves and, for example, a sonar could not detect them.