Secondary pressure calibration of measurement microphones

Recent developments are presented in the practical realization of IEC 61094-5 on the pressure calibration of working standard microphones. Particular emphasis is placed on the simultaneous comparison calibration approach, implemented in an open sound field. Limiting factors as well as those having a significant influence on the determination of the pressure sensitivity are discussed. These include the separation between the microphones, the influence of the test environment and location of the sound source, and issues arising from geometric and electroacoustic dissimilarities between the reference microphone and the microphone under test. Finally, recommendations are given for aspects to be considered in a future revision of IEC 61094-5, including contributions to the measurement uncertainty arising from the matters discussed.