Papers
R Barham and M Goldsmith (2008). Performance of a new MEMS measurement microphone and its potential application. Proceedings of the Institute of Acoustics Spring Conference 2008. Vol. 30. Pt. 2
R Barham, M Goldsmith, M Chan, et al. (2009). Development and performance of a multi-point distributed environmental noise measurement system using MEMS microphones. Proceedings of EURONOISE 2009. Edinburgh, Scotland.
The first round of noise mapping exercises, required by the European Noise Directive, are now completed, and have shown a preference towards prediction with modelling software. A possible criticism of this approach expressed by some researchers across Europe, is the lack of measurement validation in the process, which often neglected because of its intrinsic costs. This leads potentially to a reduced confidence in the final data, which is crucial for the success of the resulting action plans. DREAMSys is a measurement system that has been developed to address this problem in the future. This paper describes the development and testing of this MEMS microphone-based measurement system, under both laboratory conditions and outdoors. Results of the laboratory evaluations include key microphone parameters such as free-field frequency response and dynamic range, as well as sensitivity to environmental conditions such as temperature, atmospheric pressure and vibration. Outdoor evaluation then extends these to consider the effect of wind, rain, extreme cold and sunlight. For the first time the potential for MEMS microphones to be used in general measurement applications and for outdoor noise monitoring has been thoroughly evaluated.
R Barham, M Chan and M Cand (2010). Practical experience in noise mapping with a MEMS microphone based distributed noise measurement system. Proceedings of Internoise 2010. Lisbon, Portugal.
The first round of noise mapping exercises, required by the European Noise Directive, are now complete. A criticism of the mandated software modelling approach expressed by some researchers across Europe, is the absence of a role for measurement in the process, which is often neglected because of its high intrinsic costs. DREAMSys is a MEMS microphone based measurement system that has been developed by an industrial consortium led by NPL, to address this problem. The paper briefly describes the rationale for developing the system, and then focuses on experiences gained in deploying it at a number of test sites where long-term outdoor measurement trials are in progress. Until now, distributed measurement systems employing large numbers of sensors (5-100 or more), have been restricted to specialised applications having large financial resources available to them. DREAMSys has been designed to make wide-scale distributed measurement readily accessible to the general noise measurement practitioner. Initial results are discussed that show (a) the added value of including experimental measurements in the noise mapping process, and (b) the potential of MEMS microphones in measurement applications.