THE rumbling bass from the party animals next door need no longer keep you awake at night. Cheap and effective soundproofing can be yours in the shape of novel tiles made from latex and a few plastic buttons.
Low-frequency sounds, especially, seem to seep through most domestic walls. That鈥檚 because of their long wavelength, says at the Hong Kong University of Science and Technology in Kowloon. Bass sounds at 100 hertz have a wavelength of over 3 metres in air, 鈥渁nd several times longer in solids鈥�, he says.
To block out all sound, buildings would need walls several metres thick. Now Yang and his team have developed soundproof panels made of latex and plastic buttons, that will do the job (Applied Physics Letters, ).
Advertisement
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. 鈥淭he inner part of the membrane vibrates in opposite phase to the outer region,鈥� 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.
鈥淏y stacking five membranes, each tuned to a specific band, you can create a soundproof panel鈥�
With these panels you can soundproof homes, says Yang. And the panel鈥檚 weight is equivalent to ceramic bathroom tiles, 鈥渁lthough it鈥檚 slightly thicker at 15 millimetres鈥�, he adds.
The panels could be used 鈥渋n noisy environments such as airports鈥�, says at the University of Illinois in Urbana-Champaign. 鈥淚f these metamaterials can be manufactured economically, the impact can be very significant.鈥�
