Consideration on the efficient calibration method for low-cost microphones

Current microphone calibration methods in the international standards are basically targeting laboratory and working standard microphones specified in the IEC 61094-2 and IEC 61094-4, respectively. These methods are promising to ensure the reliability however there are many difficulties in applying it to low-cost acoustic sensors such as MEMS microphones, which are rapidly becoming widespread, with aspects of time and cost. Moreover, since the installation conditions for these low-cost microphones are different from those of standardized measurement microphones, calibration methods that take these usage conditions into consideration are required. As potential methods to overcome the problems, the feasibility of the active coupler method applicable to surface mounted condition and the bulk calibration method in the reverberation room are investigated. Both proposed methods can be applied under actual installation conditions and enable rapid and cost-efficient calibration. In this study, methods and procedures for securing traceability are proposed, and uncertainty evaluation is conducted.