Lifetime of electret microphones by thermal degradation analysis via electroacoustic measurements

Electronic equipment frequently utilises low cost electret microphones. In this paper, a complete accelerated life-test on commercial electret microphones is presented using thermal chamber testing. The test was conducted on the microphones under study at three different temperatures. After each thermal probe, the electroacoustic characteristics of each transducer was analysed for obtaining the degradation model. In the literature such tests have been performed through charge losses on the electret materials. Life models were obtained for the degradation failures revealed from the tests and a complete temperature model was then developed, which can calculate the useful life of the microphones under any of these conditions.