US 11,756,524 B2
Automatic noise control
Markus Christoph, Straubing (DE); Nikos Zafeiropoulos, Straubing (DE); Juergen Zollner, Straubing (DE); and Vasudev Kandade Rajan, Straubing (DE)
Assigned to Harman Becker Automotive Systems GmbH, Karlsbad-Ittersbach (DE)
Appl. No. 17/597,292
Filed by Harman Becker Automotive Systems GmbH, Karlsbad-Ittersbach (DE)
PCT Filed Jul. 2, 2019, PCT No. PCT/EP2019/067725
§ 371(c)(1), (2) Date Dec. 30, 2021,
PCT Pub. No. WO2021/001025, PCT Pub. Date Jan. 7, 2021.
Prior Publication US 2022/0319487 A1, Oct. 6, 2022
Int. Cl. G10K 11/178 (2006.01)
CPC G10K 11/17825 (2018.01) [G10K 11/17823 (2018.01); G10K 11/17854 (2018.01); G10K 2210/128 (2013.01)] 11 Claims
OG exemplary drawing
 
1. An automatic noise control system comprising:
an acceleration sensor configured to evaluate an amplitude of an acceleration acting thereon and to generate a reference signal x[n] representative of the amplitude of the acceleration, the acceleration being representative of unwanted noise sound generated by a noise source;
a noise control filter operatively coupled with the acceleration sensor and configured to filter the reference signal x[n] with a noise control transfer function W(z) to generate an anti-noise signal y(n);
a loudspeaker operatively coupled with the noise control filter and configured to convert the anti-noise signal y(n) into anti-noise sound;
a microphone configured to receive a noise sound after being transferred via a primary path according to a primary path transfer function from the noise source to the microphone, and the anti-noise sound after being transferred via a secondary path according to a secondary path transfer function from the loudspeaker to the microphone, and further configured to convert a sum of the received noise sound and the received anti-noise sound into an error signal e(n);
a filter controller operatively coupled with the noise control filter, the microphone and the acceleration sensor, and configured to control the noise control transfer function W(z) of the noise control filter based on the error signal e(n) from the microphone and the filtered reference signal x[n] or the unfiltered reference signal x[n] from the acceleration sensor so that the anti-noise sound after being transferred via the secondary path is the inverse of the noise sound after being transferred via the primary path;
a shadow noise control filter operatively coupled with the acceleration sensor and configured to filter the reference signal x[n] with a shadow noise control transfer function WSF(z) to generate a shadow anti-noise signal ySF(n);
a shadow filter controller operatively coupled with the shadow noise control filter and the acceleration sensor, and configured to control the shadow noise control transfer function WSF(z) of the shadow noise control filter based on a shadow error signal eSF(n) from the microphone and the filtered reference signal x[n] or the unfiltered reference signal x[n] from the acceleration sensor;
a shadow error signal generator operatively coupled with the shadow noise control filter, shadow filter controller and the microphone, and configured to generate the shadow error signal eSF(n) based on the filtered shadow anti-noise signal ySF(n) or the unfiltered shadow anti-noise signal ySF(n) from the shadow noise control filter and an estimated disturbing signal d[n];
a coefficient copy controller operatively coupled with the shadow error signal generator, the shadow noise control filter and the microphone, and configured to copy current coefficients that constitute the shadow noise control transfer function WSF(z) of the shadow noise control filter into the noise control filter to substitute the current noise control transfer function W(z) if the shadow error signal eSF(n) is smaller than the error signal e(n);
an additional noise control filter operatively coupled with the acceleration sensor and configured to filter the filtered reference signal x[n] or the unfiltered reference signal x[n] from the acceleration sensor with a transfer function that is identical with the noise control transfer function W(z) of the noise control filter to generate an additional anti-noise signal; and
a subtractor operatively coupled with the additional noise control filter and the microphone, and configured to subtract the additional anti-noise signal provided by the additional noise control filter from the error signal provided by the microphone to generate the estimated disturbing signal d[n], the estimated disturbing signal d[n] being an estimation of a disturbing sound, which is the noise sound after being transferred via the primary path from the noise source to the microphone,
wherein the shadow error signal generator comprises an adder operatively coupled with the subtractor and the shadow noise control filter, and configured to generate the shadow error signal eSF(n) based on the filtered shadow anti-noise signal ySF(n) or the unfiltered shadow anti-noise signal ySF(n) from the shadow noise control filter and the estimated disturbing signal d[n].