Microphones can always be used when the frequency range relevant to the test is covered and interference from ambient noise can either be avoided by technical measures or the ambient noise does not affect the relevant area. Microphones record airborne sound signals contactless. The detection is done spatially.
A typical application for microphones is acoustic material testing or sound testing. The typical frequency range of approx. 2 kHz up to a maximum of 50 kHz is covered and cost-effective solutions are also available for automated applications. Ambient noise can either be adequately contained by technical measures or the affected frequency range is masked out.