In a method for determining a response function of a noise cancellation enabled audio device, the audio device is placed onto a measurement fixture, wherein a loudspeaker of the audio device faces an ear canal representation of the measurement fixture. A first and a second response function between an ambient sound source and a test microphone located within the ear canal representation are measured while parameters of a noise processor of the audio device are set to a proportional transfer function with respective first and second gain factors being different from each other. A model response function is determined based on the first and the second response function and on the first and the second gain factor.