Engine and Powertrain testing is typically carried out inside a hemi-anechoic chamber to ensure high acoustic absorbency. A typical layout for test cells is with independent dynamometers sitting outside of the test chamber, leaving only the engine and gearbox inside the hemi-anechoic room.
Vehicle pass-by noise tests are conducted according to the international standard ISO 362, which quantifies the noise emission of a vehicle in an urban traffic environment, by testing on an outdoor track.