Researchers led by the Acoustic Engineering Department of the Campus de Gandia of the Universitat Politecnica de Valencia in Spain have designed an innovative structure that completely absorbs sound at a wide range of frequencies.
The breakthrough, which has been put through its paces under laboratory test conditions, may allow for new solutions to reduce noise pollution, particularly that caused by roads, railways and airplanes
Developed in collaboration with the Technical University of Denmark, France's LUNAM Universite of Le Mans and the Institute of Photonic Sciences, the new structure is made from conventional porous materials used in the construction industry.
What is rather surprising is that the new technique achieves improved sound absorption while using a smaller amount of the absorbent material.
The key to understanding this logic-defying concept is the innovative configuration of the material in periodically distributed panels. Such a distribution allows the sound waves to better penetrate the material and increases the interaction between the wave and the structure, thereby increasing the absorption level.
In this set up, a totally reflective surface becomes perfectly absorbent despite the fact that, for the most part, there is no material that absorbs sound.
"Our study tackles one of the most important problems of society today from a new point of view: the design of materials and surfaces able to significantly reduce noise," said Victor Sanchez-Morcillo, researcher and director of the Master's Degree in Acoustic Engineering which is taught at the campus.
"In view of the results, we believe we have taken an important step toward the perfect absorber. And that has been done just by reconfiguring a known material."
Sanchez said the study's conclusions open up fresh paths for the design of noise reduction solutions, such as the development of new baffles which can be situated alongside busy highways.
The full research paper has been published in the journal Scientific Reports.