NPL has developed a coupled-microphone simulator for testing the electrical measurements involved in realising the primary standard for sound pressure. (Jarvis D R, 1991. A coupled-microphone simulator for verifying apparatus used for the reciprocity calibration of microphones. Metrologia 28 425-427)
This project would involve someone from NPL takig the device to another laboratory and observing them make measurements on the device as if it were a pair of microphones undergoing a reciprocity calibration (IEC 1094 part 2). The results of the investigations may explain the descrepancies found in earlier BCR and Euromet intercomparisons.