Universities work on acoustic metamaterial to make subs ‘invisible’

Silent motorways and submarines that are undetectable to sonar.

These are dreams that the Technical University of Denmark (DTU) says could come true thanks to a new material that absorbs sound rather than reflecting it.

The university is responsible for the theoretical modelling of the sound-suppressing material that is also known as ‘acoustic metamaterial’.

DTU said it was working with a number of universities around the world in an area of research, which—for once—should ideally not make (sound) waves.

Acoustic metamaterial is a material with the capacity to change the way sound waves are reflected, such that the sound directed at the material does not create an echo and therefore ‘disappears’, so to speak. This means that it is possible to absorb the sound rather than reflecting it, thus making objects ‘invisible’ to sound, the university explained.

Development of the acoustic metamaterial is taking place in partnership with a range of educational institutions including UC Berkeley, the Karlsruhe Institute of Technology and the Hong Kong University of Science and Technology (HKUST). DTU Fotonik is responsible for the theoretical modelling, while the other parties are running practical tests in various parts of the world.

“The military is usually the first sector to show an interest in research of this kind,” Johan Christensen, PhD student at the University said and went on to explain that a metamaterial coating could, for example, make submarines exceptionally hard to detect because most detection systems use sonar and other acoustic methods to ‘see’ under water.