Active Noise Control System

• US 20090010447A1
• Filed: 08/12/2008
• Published: 01/08/2009
• Est. Priority Date: 08/15/2007
• Status: Active Grant

• Current Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Original Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Inventors: Waite, Thomas C., Kelkar, Atul G.
• Granted Patent: US 9,558,732 B2
• Time in Patent Office: Days
• US Class Current: 381/71.600
• 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 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets

Abstract

An active noise control system includes a first microphone, a controller operably coupled to the first microphone, and a speaker operably coupled to the controller. The first microphone senses a sound input in an audible spectrum, wherein the sound input includes a disturbance noise portion. The controller includes a selection unit and an output unit. The selection unit determines the disturbance noise portion of the sound input based on a highest frequency level of the sound input. The output unit removes the disturbance noise portion from the sound input to generate a filtered sound input. The speaker generates a speaker output based on the filtered sound input.

Claims

1. An active noise control system, comprising:

a first microphone configured to sense a sound input in an audible spectrum, wherein the sound input comprises a disturbance noise portion;

a controller operably coupled to the first microphone, the controller comprising a selection unit and an output unit operably coupled to the selection unit, wherein the selection unit is configured to determine the disturbance noise portion of the sound input based on a highest frequency level of the sound input, and wherein the output unit is configured to remove the disturbance noise portion from the sound input to generate a filtered sound input; and

a speaker operably coupled to the controller, the speaker configured to generate a speaker output based on the filtered sound input.

2. The active noise control system of claim 1, wherein the controller is an adaptive feedback controller to generate the filtered sound input.

3. The active noise control system of claim 1, wherein the controller is a resonant mode controller that implements adaptive feedback control to generate the filtered sound input.

4. The active noise control system of claim 3, wherein the selection unit determines the disturbance noise portion based on a Fourier transform, and wherein the output unit changes one or more coefficients to adapt to a change in the disturbance noise portion.

5. The active noise control system of claim 1, wherein the controller comprises a plurality of controllers operating in parallel to remove a plurality of disturbance noise portions from the sound input.

6. The active noise control system of claim 1, further comprising a second microphone operably coupled to the controller and located upstream to the first microphone, wherein the second microphone is configured to sense an unfiltered sound input, and wherein the controller is configured to determine the disturbance noise portion of the sound input based on both the highest frequency level of the sound input and the unfiltered sound input.

7. The active noise control system of claim 1, wherein the first microphone is located in close proximity to a user'"'"'s ear.

8. An earpiece, comprising:

a first microphone configured to sense a sound input in an audible spectrum, wherein the sound input comprises a disturbance noise portion;

a second microphone operably coupled to the controller and located upstream to the first microphone, the second microphone configured to sense an unfiltered sound input;

a controller operably coupled to the first microphone and the second microphone, the controller comprising a selection unit and an output unit operably coupled to the selection unit, wherein the selection unit is configured to determine the disturbance noise portion of the sound input based on a highest frequency level of the sound input and the unfiltered sound input, and wherein the output unit is configured to remove the disturbance noise portion to generate a filtered sound input; and

a speaker operably coupled to the first microphone and configured to generate a speaker output based on the filtered sound input.

9. The earpiece of claim 8, wherein the controller is a resonant mode controller that implements adaptive feedback control.

10. The earpiece of claim 9, wherein the selection unit determines the disturbance noise portion based on a Fourier transform, and wherein the output unit adapts to a change in the disturbance noise portion by changing one or more coefficients.

11. The earpiece of claim 8, wherein the controller comprises a plurality of controllers operating in parallel to remove a plurality of disturbance noise portions of the sound input.

12. The earpiece of claim 8, further comprising a second microphone operably coupled to the controller and located upstream to the first microphone, the second microphone configured to sense an unfiltered sound input.

13. The earpiece of claim 8, wherein the first microphone is located in close proximity to a user'"'"'s ear.

14. A method of reducing noise in a predetermined frequency band, the method comprising the steps of:

sensing a sound input in an audible spectrum, wherein the sound input comprises a disturbance noise portion;

determining the disturbance noise portion of the sound input based on a highest frequency level of the sound input;

removing the disturbance noise portion from the speaker output to generate a filtered sound input; and

generating a speaker output based on the filtered sound input.

15. The method of claim 14, wherein the step of removing the disturbance noise portion comprises the step of implementing an adaptive feedback control.

16. The method of claim 14, wherein the step of determining the disturbance noise portion comprises the step of determining the disturbance noise portion based on a Fourier transform.

17. The method of claim 14, wherein the step of removing the disturbance noise portion comprises the step of adapting to a change in the disturbance noise portion.

18. The method of claim 17, wherein the step of adapting to the change in the disturbance noise portion comprises the step of updating one or more coefficients.

19. The method of claim 14, further comprising the step of operating a plurality of controllers in parallel to remove a plurality of disturbance noise portions of the sound input.

20. The method of claim 14, further comprising the steps of:

sensing an unfiltered sound input at a second microphone; and

determining the disturbance noise portion of the sound input based on the highest frequency level of both the sound input and the unfiltered sound input.