The UK's National Physical Laboratory (NPL) has developed a new measurement-based approach to environmental noise monitoring and mapping using unique sensors. NPL in conjunction with Castle Group, QinetiQ and Hoare Lea Acoustics, and with support from the Technology Strategy Board have developed DREAMSys (a Distributed Remote Environmental Array & Monitoring System).
This new system uses a wireless array of low-cost MEMS (Micro Electro Mechanical Systems) microphones to provide a means of collecting noise data over a widespread area, for the purpose of augmenting the production and validation of noise maps.
MEMS microphones are already used widely in mobile phone and computing applications, but have yet to be exploited for precision noise measurements. This is partly because commercially available devices were not designed for such purposes and hence their performance characteristics were largely unknown in relation to measurement applications. So a key question before attempting to use MEMS microphones for measurement was how their performance compared with conventional instrumentation grade condenser microphones.
The DREAMSys project has addressed this and has successfully deployed MEMS microphones as part of a novel noise monitoring system, demonstrating for the first time their suitability for quantitative measurement and the benefits (in terms of size and cost) that they offer. The system is designed for prolonged outdoor use, so is resistant to adverse weather conditions, and powered by rechargeable battery packs in order to run unattended continuously.
EU Directive (2002/49/EC) mandates that noise maps be produced for all roads, railways and civil airports, to inform strategic planning for noise control. However, measurement based approaches using conventional sound level meters, are not practical, mainly for economic reasons. The Directive therefore requires maps to be produced from noise predictions, with all their
|Contact: David Lewis|
National Physical Laboratory