AMBIENT NOISE-REDUCTION CONTROL SYSTEM

• US 20090034748A1
• Filed: 03/28/2007
• Published: 02/05/2009
• Est. Priority Date: 04/01/2006
• Status: Abandoned Application

• Current Assignee: Wolfson Microelectronics plc (Cirrus Logic Incorporated)
• Original Assignee: Wolfson Microelectronics plc (Cirrus Logic Incorporated)
• Inventors: Sibbald, Alastair
• Application Number:
  US12/279,303
• Publication Number:
  US 20090034748A1
• Time in Patent Office: Days
• US Class Current: 381/71.600
• CPC Class Codes: G10K 11/17821 characterised by the analysis of the input signals only
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• CPC Class Codes: G10K 11/17827 Desired external signals, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 11/1783 handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
• CPC Class Codes: G10K 11/17837 by retaining part of the ambient acoustic environment, e.g. speech or alarm signals that the user needs to hear
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward
• 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 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: G10K 2210/3056 Variable gain
• 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 2460/01 Hearing devices using active noise cancellation
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones

Abstract

The invention provides a noise reduction control system for an ear-worn speaker-carrying device (“ESD”). The system is configured to sense ambient noise and to develop electrical signals which can be used to reduce the amount of said ambient noise audible to a wearer of the ESD. The system sets a plurality of predetermined and discrete noise reduction levels and automatically responds to at least one controlling event, outside the control of the wearer, to set the degree of noise reduction to one of those discrete levels. Typically, the system inverts and filters the electrical signals relating to ambient noise and feeds the inverted and filtered signals to the speaker of the ESD in time for the speaker to generate sounds capable of interfering destructively with the ambient noise.

Claims

1. A noise reduction control system for an ear-worn speaker-carrying device (“

ESD”

) comprising means for sensing ambient noise on its way towards an ear of a wearer of the ESD, for developing electrical signals indicative of said noise and for utilising said signals to reduce the amount of said ambient noise audible to a wearer of the ESD, and control means for setting a plurality of predetermined and discrete levels for said reduction;

said control means further comprising response means for automatically responding to at least one controlling event, outside the control of said wearer, to set the degree of said reduction to a preselected one of said discrete levels.

2. A system according to claim 1, wherein the system further comprises means for inverting and filtering said electrical signals and for feeding said inverted and filtered signals to a loudspeaker means in said ESD in time for the loudspeaker to generate sounds capable of interfering destructively with said sensed ambient noise when it arrives in the vicinity of said loudspeaker means.

3. A system according to claim 1, further comprising means for responding substantially instantaneously to said controlling event.

4. A system according to claim 1, further comprising means for responding to said controlling event in accordance with a predetermined time profile.

5. A system according to claim 4, wherein said predetermined time profile conforms to a ramp function.

6. A system according to claim 3, wherein said means for responding is adapted to change said degree of influence sequentially between a plurality of said discrete levels.

7. A system according to claim 2, comprising a source of further electrical signals relating to sounds intended for the wearer'"'"'s attention, and means for merging the further electrical signals with the inverted and filtered signals to create a composite signal for application to said loudspeaker means.

8. A system according to claim 7, wherein the sounds intended for the wearer'"'"'s attention comprise music.

9. A system according to claim 7, wherein the sounds intended for the wearer'"'"'s attention comprise speech or other sounds received over a telecommunications link.

10. A system according to claim 7, wherein said control means is adapted to separately control the said inverted and filtered signals and the said further electrical signals relating to sounds intended for the wearer'"'"'s attention.

11. A system according to claim 7, comprising plural channels for respective electrical signals relating to sounds intended for the wearer'"'"'s attention, and wherein said control means is adapted to separately control the said signals in at least a first and a second of said channels.

12. A system according to claim 10, wherein said control means includes a digital signal processor.

13. A system according to claim 7, adapted to receive said signals for the attention of the wearer by way of direct electrical connections.

14. A system according to claim 7, adapted to receive said signals for the attention of the listener through wireless communication.

15. A system according to claim 14, wherein said wireless communication conforms to Bluetooth protocols.

16. A system according to claim 1, adapted to receive audio signals from an audio system providing 3D-audio virtualisation.

17. A system according to claim 1, in which the selected controlling event is a function of the sensed ambient noise level.

18. A system according to claim 7, in which the selected controlling event is a function of the sounds intended for the wearer'"'"'s attention.

19. A system according to claim 1, in which the selected controlling event is a function of detected changes in physical motion of the ESD, representative of movement of the head of the wearer.

20. A personal music player incorporating one or more components of a system according to claim 1.

21. A cellular telephone incorporating one or more components of a system according to claim 1.

22. A noise reduction system comprising means for sensing ambient noise for developing electrical signals inclusive of said noise and for utilizing said signals to reduce the amount of said ambient noise audible to a wearer of the system, and control means for setting a plurality of predetermined and discrete levels for said reduction;

said control means further comprising response means for automatically responding to at least one controlling event, outside the control of the wearer, to set the degree of said reduction to a preselected one of said discrete levels.