IN-EAR DEVICE INCORPORATING ACTIVE NOISE REDUCTION

• US 20130058493A1
• Filed: 06/01/2012
• Published: 03/07/2013
• Est. Priority Date: 06/01/2011
• Status: Active Grant

• Current Assignee: Phitek Systems Limited (Amphenol Corporation)
• Original Assignee: Phitek Systems Limited (Amphenol Corporation)
• Inventors: Darlington, Paul, Azmi, Yacine, Lefebvre, Mickael Bernard Andre, Hewitt, Oliver Michael James
• Granted Patent: US 9,654,854 B2
• Time in Patent Office: Days
• US Class Current: 381/71.6
• CPC Class Codes: H04R 1/083 Special constructions of mouthpieces
• CPC Class Codes: H04R 1/1083 Reduction of ambient noise active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06
• CPC Class Codes: H04R 1/2838 of the bandpass type
• CPC Class Codes: H04R 2460/01 Hearing devices using active noise cancellation

Abstract

An in-ear device incorporating active noise reduction has a housing adapted for location in or adjacent to an auditory canal. The housing contains a driver and an acoustic path is provided from the driver to an outlet of the device. A microphone and an acoustic impedance are provided in the acoustic path. The impedance increases the stability of the device.

Claims

1. An in-ear device comprising:

a housing adapted for location in or adjacent to an auditory canal, the housing having an acoustic outlet for location in the auditory canal;

a driver provided in the housing;

an acoustic path within the housing extending from the driver to the outlet;

a microphone provided in the acoustic path between the driver and the outlet, and a high acoustic impedance provided in the acoustic path.

2. The device of claim 1 wherein the high acoustic impedance is such that the impedance of the device from the driver input to the microphone output over a selected audio frequency range is greater than the impedance of the driver over the selected audio frequency range.

3. The device of claim 2 wherein the frequency range comprises the mid-range audio frequencies.

4. The device of claim 2 wherein the frequency range is 1 kHz to 2 kHz.

5. The device of claim 2 wherein the frequency range is 200 Hz to 2 kHz.

6. The device of claim 2 wherein the frequency range is 1 kHz to 2.5 kHz.

7. The device of claim 1 wherein the high acoustic impedance is provided by a constriction in the acoustic path.

8. The device of claim 1 wherein the acoustic impedance is provided at a periphery of the microphone.

9. The device of claim 8 wherein the impedance comprises a plurality of pathways arranged around the periphery of the microphone.

10. The device of claim 9 wherein the pathways are parallel with the axis of symmetry of the microphone.

11. The device of claim 8 wherein the multiple pathways are disposed in a regular distribution around the circumference of the microphone.

12. The device of claim 7 wherein the impedance is provided between the periphery of the microphone and a wall of the device.

13. The device of claim 1 wherein the acoustic impedance is provided between the microphone and the outlet.

14. The device of claim 13 wherein the impedance comprises an acoustic resistance.

15. The device of claim 14 wherein the acoustic resistance comprises a mesh.

16. The device of claim 2 wherein the impedance is selected to improve stability of the device when used in an active noise reduction feedback or hybrid control architecture.

17. The device of any claim 1 wherein the impedance is selected to attenuate noise from a source external to the device.

18. An in-ear device comprising:

a housing adapted for location in or adjacent to the auditory ear canal, the housing having an acoustic outlet for location in the auditory canal;

a driver provided in the housing;

an acoustic path within the housing extending from the driver to the outlet;

a microphone provided in the acoustic path between the driver and the outlet;

a feedback controller for providing a signal to the driver depending upon a signal received from the microphone in order to cancel noise sensed by the microphone, and;

an acoustic impedance provided in the acoustic path adapted to improve stability of the device.

19. The device of claim 18 wherein the feedback controller is provided within the housing.

20. The device of claim 18 wherein the acoustic impedance is such that the impedance of the device from the driver input to the microphone output over a selected audio frequency range is greater than the impedance of the driver over the selected audio frequency range.

21. The device of claim 20 wherein the frequency range comprises the mid-range audio frequencies.

22. A method of improving the stability of an in-ear device having:

a housing adapted for location in or adjacent to the auditory ear canal, the housing having an acoustic outlet for location in the auditory canal;

a driver;

an acoustic path extending from the driver to the outlet;

a microphone provided in the acoustic path between the driver and the outlet; and

a feedback controller for providing a signal to the driver depending upon a signal received from the microphone in order to cancel noise sensed by the microphone,

the method comprising providing an acoustic impedance in the acoustic path which is sufficient to improve the stability of the device.

23. A method as claimed in claim 22 including the steps of determining the impedance of the driver over a selected audio frequency range, and selecting the acoustic impedance such that the impedance of the device from the driver input to the microphone output is greater than the impedance of the driver over the selected audio frequency range.

24. A method as claimed in claim 23 wherein the frequency range comprises the mid-range audio frequencies.