Recent research has shown a new approach of developing an effective and cheap soundproof system in the shape of novel tiles made from latex and few plastic buttons.
Low-frequency sounds, especially, seem to seep through most domestic walls. That's because of their long wavelength. Bass sounds at 100 hertz have a wavelength of over 3 metres in air, and several times longer in solids.
To block out all sound, buildings would need walls several metres thick. Now Zhiyu Yang and his team have developed soundproof panels made of latex and plastic buttons that will do the job.
These noise-cancelling panels consist of a latex rubber membrane stretched over a 3-millimetre-thick rigid plastic grid of 1-centimetre-wide squares. In the middle of each square is a small, weighted, plastic button.
When sound waves hit the panel, the membrane and weighted buttons resonate at difference frequencies. "The inner part of the membrane vibrates in opposite phase to the outer region," says Yang. That means the sound waves cancel each other out and no sound gets through.
Each weighted membrane only cancels out sound waves within a small band of frequencies. “But changing the weight of the buttons alters the operational frequency,” says Yang. By stacking five membranes together, each tuned to a specific band, you can create a soundproof panel that works in the range from 70 to 550 hertz.
CellPhone Vibrations aid mind-control movement as the researchers placed 12 phone vibrators, positioned like the numbers on a clock, on a belt worn around the wheelchair user's waist. These vibrate sequentially for 3 seconds each. If they wearer wants to go, say, in a 4 o'clock direction, they wait until the appropriate "tactor" vibrates and then think "that one". "That generates a P300 and selects the movement direction you want," says Brouwer.
