Estimates for the number of people in the UK suffering from work-related noise-induced hearing loss can vary from around 75,000 to over 500,000. As a result of health & safety compliance legislation, awareness education, and injury compensation claims, improvements have been slowly made over the years, although widespread workplace noise levels still exist.

Whereas historically, industrial deafness was most prevalent in heavy manufacturing, textiles factories, mines, dockyards and railways, awareness has been raised with potentially problem noise levels to be found in many other types of today’s light industrial working environments.

A recent scientific development, reported in the New Journal of Physics, may produce a breakthrough in the enduring problems of reducing the scale of potential occupational hearing damage.

Intriguingly called the “Cloak of Silence”, the Spanish scientists who have been working on the project, have harnessed the technology of “sonic crystals”, a form of meta-material made of artificial composites, which can render an object effectively invisible to sound waves.

Although the mathematics behind the principles of cloaking have been known for a number of years, the type of materials from which a cloak can be made, have not been available. The cloaking process may be likened to placing an object in a river to divert the passage of water, so although a sound might exist, anyone within the confines of the meta-material layered Cloak of Silence will not be exposed.

Simulations showed that 200 layers of metamaterial could effectively shield an object from noise, whilst thinner stacks would shield an object from certain frequencies, the thickness depending on the wavelength required to be screened.

An obvious first application would be to help soundproof all noisy workplaces as well as improve acoustics in music theatres, help conceal submarines from sonar detection, etc.

Although practical working models of the technology are still in the research and development stage, it is anticipated that it may be more immediately utilised in the form of helmets or ear defenders for industries as varied as mining, construction, fabrications and the music industry.