The microphone system will eventually be configured to in-ear hearing protection that also acts as a radio communication device.
The system uses between five and 10 1mm2 microphones, an electronic compass and a microchip to calculate where the sound of gunfire is coming from, with a margin of error of three per cent for direction and 10 per cent for distance based on trials on a firing range.
‘We’re using MEMS [micro-electromechanical systems]-based microphone technology, which is allowing us to integrate the microphones within the fabric of the clothing because they’re very small and lightweight and very low power,’ research fellow Dr Dylan Banks told The Engineer.
‘It effectively becomes burdenless for the soldier because they’re not carrying an extra box. They don’t even notice the difference in weight between wearing 10 microphones in the cover of their helmet.
The researchers, who have spun out a company called Vorpal to commercialise the technology, are also developing headphones that will protect soldiers from around 25 decibels of low-frequency noise and provide a way to alert them of the gunfire direction.
‘Currently, if you’re wearing these [hearing protectors], 30 per cent of the time you get confused as to whether the noise is coming from behind or in front. But it’s really easy for us to tell you that,’ said Banks.
The key to creating a system so small it could run on a watch battery was using analogue circuitry, which is very efficient because the size and shape of the transistors are designed so that it can only perform a single function.
‘The challenge was getting the algorithm simple enough and robust enough so that it can be implemented within an analogue circuitry system,’ said Banks.
The company, which has received a development grant from the government’s Defence Science and Technology Laboratory (Dstl), is currently determining the best way to alert soldiers of the direction of gunfire, for example, verbal or non-verbal audio signals.
It hopes to bring the helmet system to market within 12 months, followed by a second version with a fully integrated power and processing system six months later, with the hearing-protection system expected within a similar timeframe.