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. The system employs high capability acoustic drivers, powerful audio amplifiers, a narrow-band multiple-input-multiple-output (MIMO) controller and precision laboratory microphones to produce an acoustic environment that can simulate a helicopter, aircraft, jet engine or launch vehicle sound pressure field. A high level system is capable of overall sound pressure levels in the 125–154 dB for more than one minute over a frequency range from 15 Hz to 31 kHz.