Holes can help attenuate sound

2008/11/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Fisika

To silence the noisy pieces of a machinery, the ideal would be to drill these pieces. These holes reduce the sound transmitted in several wavelengths. This has been deducted by researchers from the Polytechnic University of Valencia and the Optics Institute of Madrid.

For this purpose, the team of researchers placed several plates in the water of a millimetre thick, emitting ultrasounds on a part of the plate through a transducer and measuring the transmitted sound with the help of another transducer. When drilling these plates it was observed that less sounds were transmitted. This transmission depends on the thickness of the plates, the diameter of the holes, the separation between holes and the arrangement of the holes. The attenuation of the sound is greater when the separation between holes is equal to the wavelength of the sound.

Although research has been conducted on water, experts believe that this would also occur in the air. Furthermore, it is possible that these perforated plates will be used in the future for the manufacture of acoustic metamaterials.