Active noise equalization
View Patent ↗An active noise equalization (ANE) system may be run on the existing audio/infotainment system as a software library. The ANE system may share components (e.g., microphones and sensors) with other audio applications. Some ANEs include a complex-domain formulation of a multiple-frequency multiple-channel ANE that requires less memory and processing requirements. The complex-domain system replaces the multiplication of multiple real gains with multiple real signals with a single complex multiplication operation.
1. A method for active noise equalization comprising:
obtaining a sync signal from a noise source reproduced into an acoustic space;
generating a noise model, representing one or more complex tones, responsive to the sync signal;
receiving an audio signal representing a sound field in the acoustic space;
applying an estimate of a secondary path transfer function to the noise model in a frequency domain; and
applying a transformation function to the noise model where the transform function is responsive to reducing a sum of the output of the transformation function and the received audio signal;
where applying the estimate of the secondary path transfer function comprises an online calculation; and where an output of the secondary path transfer function is limited to a range of frequencies that lies within an aural range.
2. The method for active noise equalization of claim 1 , where applying the estimate of the secondary path transfer function to the noise model comprises calculating a plurality of frequency components in a region of interest.
3. The method for active noise equalization of claim 2 , where the estimate of the secondary path transfer function for the plurality frequency components in the region of interest is stored in a non-transitory media.
4. The method for active noise equalization of claim 1 , where the transformation function comprises an adaptive filtering algorithm.
5. The method for active noise equalization of claim 4 , where the adaptive filtering algorithm comprises one of a least-mean-square, a normalized least-mean-square, an affine projection or a recursive least-square.
6. The method for active noise equalization of claim 1 , where the received audio signal is generated by an automobile, an aircraft, a heating and ventilation system or received within a manufacturing environment.
7. A system for active noise equalization comprising:
one or more processors; and
memory storing instructions accessible by the one or more processors, the instructions, when executed by the one or more processors, configuring the system to:
obtain a sync signal associated with a noise source reproduced in an acoustic space;
generate a noise model representing one or more complex tones responsive to the sync signal;
receive an audio signal representing a sound field in the acoustic space;
apply an estimate of a secondary path transfer function to the noise model in a frequency domain; and
apply a transformation function to the noise model where the transform function is based on the noise model and is responsive to reducing a sum of the output of the transformation function and the received audio signal
where the one or more processors apply the estimate of the secondary path transfer function through an online calculation; and where an output of the secondary path transfer function is limited to a range of frequencies that lies within an aural range.
8. The system for active noise equalization of claim 7 , where a controller applies the estimate of the secondary path transfer function to the noise model through a plurality of frequency components in a region of interest.
9. The system for active noise equalization of claim 8 , where the estimate of the secondary path transfer function for the plurality of frequency components in the region of interest is stored in a local non-transitory media.
10. The system for active noise equalization of claim 7 , where the transformation function comprises an adaptive filtering algorithm.
11. The system for active noise equalization of claim 10 , where the adaptive filtering algorithm comprises one of a least-mean-square, a normalized least-mean-square, an affine projection or a recursive least-square.
12. The system for active noise equalization of claim 7 , where the received audio signal is generated by an automobile, an aircraft, a heating and ventilation system or a manufacturing environment.
13. A computer readable medium comprising instructions, stored on a non-transitory medium executable by a processor, for:
obtaining a sync signal from a noise source reproduced in an acoustic space;
generating a noise model representing one or more complex tones responsive to the sync signal;
receiving an audio signal representing a sound field in the acoustic space;
applying an estimate of a secondary path transfer function to the noise model in a frequency domain; and
applying a transformation function to the noise model where the transform function is responsive to reducing a sum of the output of the transformation function and the received audio signal
where applying the estimate of the secondary path transfer function comprises an online calculation; and where an output of the secondary path transfer function is limited to a range of frequencies that lies within an aural range.
14. The computer readable medium of claim 13 where the instructions stored on the non-transitory media are further executable by the processor for discarding an output of the secondary path transfer function when the output of the secondary path transfer function lies outside a defined frequency range.
15. The computer readable medium of claim 13 where the instructions stored on the non-transitory media are further executable by the processor for deriving the secondary path transfer function through an interpolation.
16. The system for active noise equalization of claim 7 , where the instructions, when executed by the one or more processors, further configures the system to discard an output of the secondary path transfer function when the output of the secondary path transfer function lies outside a defined frequency range.
17. The system for active noise equalization of claim 7 , where the instructions, when executed by the one or more processors, further configure the system to derive the secondary path transfer function through an interpolation.
18. The method for active noise equalization of claim 1 , further comprising discarding an output of the secondary path transfer function when the secondary path transfer function lies outside of a defined frequency range.
19. The method for active noise equalization of claim 1 , further comprising deriving the secondary path transfer function through an interpolation.