Some investigations relating to the calibration of probe microphones

It has been the practice in the Post Office Research Station to use the technique of a Rayleigh disk in a resonant tube for obtaining pressure calibrations of microphones, particularly probe microphones. The accuracy of such calibrations has long been known from fundamental considerations to be suspect above about 4 kc/s, for the tube of diameter 4.5 cm which has been found convenient for general use so far. This paper describes and gives the results of an attempt to check the accuracy of this limit.