Introduction of a Novel Analysis Method to Predict the Performance of Secondary Systems

Nowadays active noise control (ANC) systems are used in many different fields of applications. Earth moving machineries, cars, trains or airplanes are among of these applications, just to name a few. Thereby one is often confronted with the problem, that an already installed playback or sound system has to be used as secondary system to fight the undesired noise.Taking the car as an example, there it is the case that the sound system, incorporating the already installed speakers, has to be used to create zones-of-silence at one or several positions within the interior of the automobile.Knowing about the theoretically achievable performance of this secondary system would be beneficial in assessing the operational spectral range of the ANC-system.In this presentation a method will be disclosed allowing making realistic predictions of the limitations of the secondary system, to which one is bounded. Thereby, the only presumption is that a perfect primary system is expected, i.e. reference sensors delivering signals showing a perfect coherence to the signals picked-up by the utilized error microphones.The prediction is based on secondary path measurements done within the desired zones-of-silence, which ideally should be located, close to the foreseen error microphone positions.