Kingan M., Pearse J.

The suitability of making aeroacoustic noise measurements in a wind tunnel using a microphone immersed in the airflow was assessed. When a microphone is immersed in airflow, turbulence within the airflow interacts with the microphone diaphragm causing it to vibrate. This vibration produces a signal from the microphone due to the turbulence/diaphragm interaction and is not due to an acoustic wave. This turbulence-induced 'pseudo noise’ is equivalent to a background noise source and is typically of a relatively high level in comparison to the level produced by aeroacoustic sources. In this paper a number of different microphones and microphone treatments were investigated for their suitability for minimizing the pseudo noise.