Sound system

Work starts this week to develop a new generation of sonar technology, based on the biological systems found in bats and dolphins.


A consortium of UK university researchers has been awarded £3.4m by the EPSRC to harness these natural acoustic abilities and in a four-year programme will apply them to a range of engineering disciplines such as biomedicine and underwater sonar.



Bats and cetaceans such as dolphins and porpoises have vastly superior capabilities to existing sonar technology in resolution, object identification and material characterisation.



Past projects have made little progress in directly copying biological sonar systems. But it is now hoped that with sufficient funding and by bringing together for the first time all the relevant experts in biology and engineering, it will be possible to make a breakthrough in high-resolution acoustic imaging and physical characterisation of objects with sonar.



The technology, which would also have a range of applications in materials characterisation and non-destructive evaluation, would be especially valuable in the search for natural resources such as oil and gas beneath the seabed.



The project is led by the British Geological Survey, which is also working closely with the geology department of Leicester University. Mike Lovell, the university’s professor of petrochemistry said: ‘Some work has been done on this before, but it has not been applied in the right areas. This project is looking for a quantum leap in what you will be able to do with sonar.’



Lovell’s work will tackle the critical limitation that is inherent in all current acoustic technologies, namely the resolution and ‘energy compromise’.



Conventional sonar is only of limited use for examining the geology below the seabed. The high- frequency sonar necessary for high-resolution acoustic images is very quickly attenuated by rock and other solid bodies. Higher energy, longer wavelength sonar might penetrate more deeply, but will not produce the same resolution.


How biological sonar systems get around this problem is one of the greatest secrets yet to be revealed. ‘There are some creatures out there that use sonar to identify the difference in shape and properties of materials that are otherwise similar. We want to know how they do that,’ said Lovell.



Such an ability could also be useful in the waste disposal industry, he said. Enhanced sonar capabilities would allow scientists to better identify and characterise rock in terms of its porous quality and the fissures within. The ability to build an accurate picture of fissure networks and how they are connected would make it possible to determine the movement of fluid through the ground.



The project will draw on expertise in animal acoustics from Leeds University; mathematical and signal processing theory from Strathclyde University and acoustical transducer design from Southampton University. A team at Edinburgh University will investigate possible applications for enhanced sonar in medical imaging.



The project’s first step will be to gain an improved understanding of animal acoustics, particularly with regard to signal generation and subsequent processing. The programme will undertake experiments on well-calibrated targets to understand some of the acoustic features used by bats and cetaceans, and make use of this to develop parallel features in technology. The findings will be applied to transducer and array design.