Direct-field acoustic testing
Direct-field acoustic testing, (DFAT), is a technique used for acoustic testing of aerospace structures by subjecting them to sound waves created by an array of acoustic drivers. The method uses electro-dynamic acoustic loudspeakers, arranged around the test article to provide a uniform, well-controlled, direct sound field at the surface of the unit under test.
Source: Wikipedia — Direct-field acoustic testing (CC BY-SA 4.0)