SYSTEM FOR ACTIVE NOISE CONTROL WITH PARALLEL ADAPTIVE FILTER CONFIGURATION

• US 20100177905A1
• Filed: 01/12/2009
• Published: 07/15/2010
• Est. Priority Date: 01/12/2009
• Status: Active Grant

• Current Assignee: Harman International Industries Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Harman International Industries Incorporated (Samsung Electronics Co. Ltd.)
• Inventors: Shridhar, Vasant, Wertz, Duane
• Granted Patent: US 8,718,289 B2
• Time in Patent Office: Days
• US Class Current: 381/71.110
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17855 for improving speed or power requirements
• CPC Class Codes: G10K 11/17879 using both a reference signal and an error signal
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone

Abstract

An active noise control system includes a plurality of adaptive filters. The plurality of adaptive filters each receives an input signal representative of an undesired sound. The adaptive filters may each generate an output signal based on the input signal. The output signals are used to generate an anti-noise signal configured to drive a speaker to produce sound waves to destructively interfere with the undesired sound.

Claims

1. An active noise control system comprising:

a plurality of adaptive filters each configured to receive a same input signal representative of an undesired sound and to receive a respective update signal, where the adaptive filters are configured to generate respective output signals based on the same input signal, where each of the respective output signals is independently adjusted based on the respective update signal, and where at least one of the respective output signals is an anti-noise signal configured to drive a speaker to produce sound waves to destructively interfere with the undesired sound.

2. The active noise control system of claim 1, where the plurality of adaptive filters includes a first adaptive filter corresponding to a first predetermined frequency range and a second adaptive filter corresponding to a second predetermined frequency range, where the first adaptive filter is configured to converge at a faster rate than the second adaptive filter when the same input signal includes a dominant signal component within the first predetermined frequency range.

3. The active noise control system of claim 2, where the output signal of the first adaptive filter and the output signal of the second adaptive filter summed together to produce the anti-noise signal, where the output signal of the first adaptive filter is a more significant portion of the anti-noise signal than the output signal of the second adaptive filter when the dominant component of the same input signal is within the first predetermined frequency range.

4. The active noise control system of claim 2, where the output signal of the first adaptive filter and the output signal of the second adaptive filter are summed together to produce the anti-noise signal, where the output signal of the first adaptive filter is a less significant portion of the anti-noise signal than the output signal of the second adaptive filter when the dominant component of the same input signal is within the first predetermined frequency range.

5. The active noise control system of claim 2, where the second adaptive filter is configured to converge at a faster rate than the first adaptive filter when the same input signal includes a dominant component within the second predetermined frequency range.

6. The active noise control system of claim 2, where the first predetermined frequency range overlaps the second predetermined frequency range.

7. The active noise control system of claim 1, where each of the output signals is at least a portion of the anti-noise signal.

8. A sound reduction system comprising:

a processor; and

an active noise control system stored in memory and executable on the processor, where the active noise control system includes a plurality of adaptive filters, and where each of the plurality of adaptive filters are configured to;

receive an input signal representative of an undesired sound; and

generate a respective output signal based on the input signal, where the respective output signal of each of the plurality of adaptive filters is independently adjusted based on a respective control signal, and where at least one respective output signal is an anti-noise signal configured to drive a speaker to produce sound waves to destructively interfere with the undesired sound.

9. The sound reduction system of claim 8, where the at least one respective output signal is generated by at least one of the plurality of adaptive filters that is first to converge.

10. The active noise control system of claim 8, where a filter length of each of the plurality of adaptive filters is different.

11. The active noise control system of claim 10, where the filter length of each of the adaptive filters corresponds to a respective predetermined frequency range.

12. The active noise control system of claim 8, where the plurality of adaptive filters includes a first adaptive filter having a first filter length and a second adaptive filter having a second filter length that is different from the first filter length.

13. The active noise control system of claim 12, where the first filter length corresponds to a first predetermined frequency range and the second filter length corresponds to a second predetermined frequency range, and where the first frequency range and the second frequency range overlap.

14. The active noise control system of claim 12, where the first filter length corresponds to a first predetermined frequency range and the second filter length corresponds to a second predetermined frequency range, and where the first adaptive filter is configured to converge faster than the second adaptive filter when the input signal includes a dominant signal component in the first predetermined frequency range.

15. The active noise control system of claim 8, where the input signal has a frequency range and the plurality of adaptive filters are each configured to receive the input signal over the entire frequency range.

16. The active noise control system of claim 8, where at least one of the adaptive filters is operable in a frequency range that is closest to the undesired sound is first to converge and to produce anti-noise configured to drive a speaker to produce sound waves to destructively interfere with the undesired sound.

17. The active noise control system of claim 8, where each adaptive filter is operable in a predetermined frequency range to converge to an anti-noise signal corresponding to an undesired sound in a predetermined frequency range.

18. The active noise control system of claim 8, where the input signal is a single input signal of a predetermined frequency range.

19. A method of generating an anti-noise signal comprising:

receiving an input signal indicative of an undesired noise;

transmitting the input signal to an input of each of a plurality of adaptive filters;

generating output signals from each of the plurality of adaptive filters; and

generating the anti-noise signal based on at least one of the output signals.

20. The method of claim 19, where generating the anti-noise signal comprises generating the anti-noise signal based on at least one of the output signals from at least one of the plurality of adaptive filters that is first to converge.

21. The method of claim 19, where transmitting the input signal to an input of each of a plurality of adaptive filters comprises transmitting the input signal to a first input of a first adaptive filter and a second input of a second adaptive filter, where the first adaptive filter has a first filter length and the second adaptive filter has a second filter length that is different from the first filter length.

22. The method of claim 19, where the first filter length corresponds to a first predetermined frequency range and the second filter length corresponds to a second predetermined frequency range, where the first predetermined frequency range and the second predetermined frequency range overlap.

23. The method of claim 19, where transmitting the input signal to an input of each of a plurality of adaptive filters comprises transmitting the input signal to a first input of a first adaptive filter corresponding to a first predetermined frequency range and a second input of a second adaptive filter corresponding to a second predetermined frequency range, where the first adaptive filter converges faster than the second adaptive filter when the input signal includes a dominant signal component in the first frequency range.

25. The computer-readable memory of claim 23 further comprising instructions executable to generate an anti-noise signal based on a first one of the plurality of output signals corresponding to a first one of the plurality of adaptive filters that converges.

24. A computer-readable medium encoded with computer executable instructions, the computer executable instructions executable with a processor, the computer-readable medium comprising:

instructions executable to receive an input signal representative of an undesired sound;

instructions executable to generate a plurality of adaptive filters;

instructions executable to transmit the input signal to the plurality of adaptive filters;

instructions executable to generate a plurality of output signals, where each of the plurality of output signals corresponds to a respective output of one of the plurality of adaptive filters; and

instructions executable to generate an anti-noise signal based on at least one of the plurality of output signals, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with the undesired sound.

26. The computer-readable medium of claim 24 further comprising:

instructions executable to generate a first adaptive filter having a first filter length and the second adaptive filter has a second filter length that is different from the first filter length; and

instructions executable to transmit the input signal to an input of each a first input of the first adaptive filter and a second input of the second adaptive filter.

27. The computer readable medium of claim 26, where the first filter length corresponds to a first predetermined frequency range and the second filter length corresponds to a second predetermined frequency range, where the first predetermined frequency range and the second predetermined frequency range overlap.

28. The computer readable medium of claim 24 further comprising:

instruction executable to generate a first input of a first adaptive filter corresponding to a first predetermined frequency range and a second input of a second adaptive filter corresponding to a second predetermined frequency range; and

instructions executable to transmit the input signal to a first input of the first adaptive filter and to a second input of the second adaptive filter, where the first adaptive filter converges faster than the second adaptive filter when the input signal includes a dominant signal component in the first frequency range.