SYSTEM FOR ACTIVE NOISE CONTROL WITH AUDIO SIGNAL COMPENSATION

• US 20100124336A1
• Filed: 11/20/2008
• Published: 05/20/2010
• Est. Priority Date: 11/20/2008
• 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 8,135,140 B2
• Time in Patent Office: Days
• US Class Current: 381/71.400
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• CPC Class Codes: G10K 11/17825 Error signals
• CPC Class Codes: G10K 11/17827 Desired external signals, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17879 using both a reference signal and an error signal
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/128 Vehicles

Abstract

An active noise control system generates an anti-noise signal to drive a speaker to produce sound waves to destructively interfere with an undesired sound in a targeted space. The speaker is also driven to produce sound waves representative of a desired audio signal. Sound waves are detected in the target space and a representative signal is generated. The representative signal is combined with an audio compensation signal to remove a signal component representative of the sound waves based on the desired audio signal and generate an error signal. The active noise control adjusts the anti-noise signal based on the error signal. The active noise control system converts the sample rates of an input signal representative of the undesired sound, the desired audio signal, and the error signal. The active noise control system converts the sample rate of the anti-noise signal.

Claims

13. A method of reducing volume of an undesired sound present in a space comprising:

generating an input signal representative of the undesired sound present in the space;

removing a portion of the input signal representative of an audio signal; and

generating an anti-noise signal based on the input signal with the portion removed to drive a loudspeaker to produce an audible signal to destructively interfere with the undesired sound.

14. The method of claim 13, where removing the portion from the input signal comprises:

generating an audio compensation signal; and

combining the audio compensation signal with the input signal.

15. The method of claim 13, where generating an audio compensation signal further comprises filtering the audio the audio signal with an estimated audio path filter.

16. The method of claim 13 further comprising converting the anti-noise signal from a first sample rate to a second sample rate, where the second sample rate is higher than the first sample rate.

17. The method of claim 14, further comprising converting the audio compensation signal from a first sample rate to a second sample rate, where the first sample rate is higher than the second sample rate.

18. The method of claim 13, further comprising converting the input signal from a first sample rate to a second sample rate, where the first sample rate is higher than the second sample rate.

19. A plurality of instructions stored on a memory device that, when executed by a processor, cause the processor to:

sample a first input signal at a first predetermined sample rate, where the first input signal is representative of sound in a target space;

sample an audio signal at the first predetermined sample rate to generate a first audio signal;

sample the audio signal at 192 kHz to generate a second audio signal;

combine the first audio signal with the input signal to generate an error signal;

convert the sample rate of the error signal from 192 kHz to the first predetermined sample rate;

generate an anti-noise signal based on the error signal; and

combine a second audio signal and the anti-noise signal to generate an audio output signal.

1. A sound reduction system comprising:

a processor; and

an active noise control system executable by the processor, the active noise control system configured to;

receive an input signal representative of sound present in a target space, remove a first signal component from the input signal to generate an error signal, and generate an anti-noise signal based on the error signal, where the anti-noise signal is configured to drive a loudspeaker to produce an audible sound to destructively interfere with an undesired sound present in the target space.

2. The system of claim 1, where the first signal component is representative of an audio signal generated by an audio system.

3. The system of claim 1, where the active noise control system is further configured to combine an audio compensation signal with the first input signal to remove the first signal component.

4. The system of claim 3, where the audio compensation signal is based on the audio signal.

5. The system of claim 3, where the active noise control system is configured to filter the audio signal with an estimated audio path filter to produce the audio compensation signal.

6. The system of claim 3, where the active noise control system is further configured to convert the audio signal from a first sample rate to a second sample rate.

7. The system of claim 6, where the active noise control system is further configured to convert the input signal from a third sample rate to a fourth sample rate.

8. The system of claim 7, where the fourth sample rate is the second sample rate.

9. The system of claim 8, where the second sample rate is approximately 4 kHz.

10. The system of claim 6 where the first sample rate is about 48 kHz.

11. The system of claim 7, where the third sample rate is about 192 kHz.

12. The system of claim 1, where the anti-noise signal is converted from a first sample rate to a second sample rate higher than the first sample rate.

20. The plurality of instructions of claim 19, when executed by the processor, further cause the processor to filter the first audio signal with an estimated audio path filter.

21. The plurality of instructions of claim 19, when executed by the processor, further cause the processor to sample the anti-noise at the first predetermined sample rate.

22. The plurality of instructions of claim 21, when executed by the processor, further cause the processor to convert a sample rate of the anti-noise signal from the first predetermined sample rate to 192 kHz, where the first predetermined sample rate is less than 192 kHz.

21-1. The plurality of instructions of claim 19, when executed by the processor, further cause the processor to:

sample the first input signal at 192 kHz; and

convert a sample rate of the input signal from 192 kHz to the first predetermined sample rate.

24. A method of generating a plurality of estimated path filters of an active noise control system comprising:

selecting a first physical path present in the active noise control system;

selecting a second physical path present in the active noise control system;

inputting a first signal through the first physical path to generate a first output signal;

inputting the first signal through the second physical path to generate a second output signal;

comparing the first signal to the first output signal to generate a first transfer function based on the first physical path;

comparing the first signal to the second output signal to generate a second transfer function based on the second physical path; and

generating a first estimated path filter based on the first transfer function and a second estimated path filter based on the second transfer function.

25. The method of claim 24, where the first physical path includes a path traversed by an audio signal within the active noise control system.

26. The method of claim 25, where the first physical path further includes a path traversed by an audible signal representative of an audio signal.

27. The method of claim 24, where the second physical path includes a path traversed by an anti-noise signal within the active noise control system.

28. The method of claim 27, where the second physical path includes a path traversed by an audible signal representative of the anti-noise signal.