University of Salford Manchester

Salford research provides sound foundation for advanced ear protectors

Wednesday 27 February 2013

Researchers at the University of Salford have designed highly advanced artificial materials that can be used to shield low frequency noise in military or industrial environments.

Low frequency noise is traditionally difficult to cut out without the use of heavy walls and barriers but, by using the emerging science of metamaterials, the researchers at Salford have created a design which could be incorporated into a wearable set of earmuffs.

Metamaterials are entirely artificial materials that cannot be found in nature.  At Salford, physicists have already been part of research to design materials that make objects invisible and have now turned their attentions to the uses of this revolutionary technology to affect sound.

Using a combination of measurement and modelling metamaterials comprised of several thin membranes which have been created and tested in the University’s acoustics labs, the team now believe that it is possible for a working prototype to be created which can be tested in environments such as armoured vehicles or airports, where extreme levels of low frequency noise have serious health implications for people.

For electromagnetic waves, metamaterials can take many forms, such as a series of coils and wires that have the ability to bend waves around them in a predefined way.  There are numerous and enormously promising applications for this technology.  As well as invisibility and sound reduction, the ability to bend light will lead to significantly increased computing processing speeds in the future.

Thanks to the unique properties of the metamaterials it is also possible to configure the earmuffs so that other frequencies can be heard – for example human voices – whilst the more damaging frequencies are cut out.

Professor Allan Boardman from the School of Computing, Science & Engineering led the Salford team which worked on the designs.  “Metamaterials have a great deal of potential for a wide range of crucial uses and at Salford we’re proud to be leading in their development,” he said.

“We now believe it is quite possible to build these earmuffs which will prove extremely useful in environments where low frequency noise is a real hazard to health.”

If you would like further information on this project please email Dr Olga Umnova or Professor Allan Boardman.

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