Noise reduction system having a nonlinearity filter unit, method of operating the system and use of the system

A method of operating a noise reduction system for actively compensating background noise generated by a noise source in a noise reduction area in a passenger transport area of a vehicle, the noise reduction system comprising a controller comprising hardware, a reference sensor configured to detect the background noise generated by the noise source, a sound generator configured to generate anti-noise for superimposing the anti-noise with the background noise in the noise reduction area for active reduction of the background noise, and a monitor-microphone array comprising a plurality of monitor microphones, the monitor-microphone array being disposed adjacent to the noise reduction area and being configured to pick up the background noise emitted generated by the noise source and the anti-noise generated by the sound generator, wherein the controller is configured by a virtual sensing algorithm to estimate an error signal at a position of a virtual microphone, and wherein the virtual microphone is located in the noise reduction area and the error signal is indicative of a summation between the background noise and the anti-noise at the position of the virtual microphone,

• the method comprising:
• generating, by the noise reduction system, an anti-noise signal for driving the sound generator to generate the anti-noise;
• generating a corrected anti-noise signal by applying a non-linear filter function on the anti-noise signal, which is based on a model of a non-linear transfer function of the sound generator in that a non-linear response of the sound generator is at least partially corrected when driven by the corrected anti-noise signal;
• and
• outputting the corrected anti-noise signal to the sound generator,
• wherein the sound generator is an electromechanical device and the model of the non-linear transfer function is an adaptive model which adapts on a change in at least one mechanical parameter of the sound generator.

A processing apparatus for actively compensating background noise generated by a noise source in a noise reduction area in a passenger transport area of a vehicle, the processing apparatus comprising:

• a controller comprising hardware, the controller being configured by a virtual sensing algorithm to estimate an error signal at a position of a virtual microphone,
• wherein the virtual microphone is located in the noise reduction area and the error signal is indicative of a summation between background noise generated by the noise source as detected by a reference sensor and anti-noise generated by a sound generator for superimposing the anti-noise with the background noise at the position of the virtual microphone for active reduction of the background noise;
• wherein the controller is configured to:
• generate an anti-noise signal for driving the sound generator to generate the anti-noise;
• generate a corrected anti-noise signal by applying a nonlinear filter function on the anti-noise signal, which is based on a model of a non-linear transfer function of the sound generator in that a non-linear response of the sound generator is at least partially corrected when driven by the corrected anti-noise signal;
• and
• output the corrected anti-noise signal to the sound generator, and
• wherein the sound generator is an electromechanical device and the model of the non-linear transfer function is an adaptive model configured to adapt on a change in at least one mechanical parameter of the sound generator.