Identification of failure markers in noise measurement low cost devices

One of the purposes of the DYNAMAP project is the development of low cost sensors, which allow a widespread and continuous noise monitoring.Consumer microphones have been disruptively introduced in the audio market since 70's as prepolarized electrect condenser. At beginning of 2000 a second revolution started in microphone's industry with the introduction of mems devices. Both those kind of microphone are available in low cost versions and they could be used for the production of Class I instruments. Nevertheless they are not commonly implemented in outdoor noise monitoring systems because of their lack of stability over long time periods when exposed to environmental agents. In this study an evaluation of low cost microphones performances over time is presented, in order to find markers that point out when the measurement chain specifications are falling out of standards requirements of IEC 61672. More in detail, the testing phase is carried out by measuring electrical floor noise distribution and frequency response variations when the sensors are exposed to simulated stress conditions.