According to a study published inApplied Physics Lettersand which the magazine echoesNew ScientistIn order to completely block the sounds that pass through the walls of our homes, in theory, walls several meters thick would be needed. Zhiyu Yang has developed an alternative consisting of panels made up ofa latex membrane stretched over a rigid plastic panel3 millimeters thick, arranged in one-centimeter square meshes. In the center of each box is a small, heavy plastic button. When sound waves hit the frame, the membrane and buttons resonate at different frequencies. The inner part of each membrane vibrates in opposition to the outer zone, which makessome sound waves cancel out others, silencing any sound.
In this innovative structure, each membrane can be configured to block a certain frequency of sound. And combining five (a total thickness equivalent to the ceramic tiles on the wall of our bathrooms) you couldblock noise in the 70 to 550 hertz frequency range, as Yang has shown. Enough considering that male voices have a frequency between 70 and 200 hertz, while female voices oscillate between 150 and 400 hertz.