Due to the air flow around the measured object, using conventional acoustic measuring techniques for exterior noise measurements in wind tunnels is problematic. On the one hand, there is so-called "pseudo sound" on the microphone caused by alternating pressure flow hitting the measuring diaphragm. On the other hand, flow noises and therefore extraneous noises which interfere with the measurement are generated on microphone housings, pre-amplifiers and holders,. For exterior noise measurement, specially developed measuring techniques are therefore often used, such as using special probes, microphone arrays or acoustic mirrors.