Theoretical study and experiment on frequency characteristics of a probe microphone

A probe microphone has a thin, empty and long probe tube. Therefore, frequency characteristics of a probe microphone are not good. In this paper, we analyze a probe microphone constructed by a probe, a spacer and a regular microphone. In this microphone, the sound wave is attenuated by viscosity of air. So, sound solution is given with the attenuation constant δ and the phase constant K. As a result, frequency characteristics of a probe microphone were obtained for the size of the probe tube, δ and K. In the experiment, applying a white noise or a rectangular signal to the speaker,sound from the probe microphone was compared with that of the regular microphone. Experimental results agreed well with the theoretical ones