METHOD AND SYSTEM FOR SURROUND SOUND BEAM-FORMING USING VERTICALLY DISPLACED DRIVERS

• US 20070263888A1
• Filed: 05/31/2006
• Published: 11/15/2007
• Est. Priority Date: 05/12/2006
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Melanson, John
• Granted Patent: US 7,606,377 B2
• Time in Patent Office: Days
• US Class Current: 381/300
• CPC Class Codes: H04R 1/403 loud-speakers
• CPC Class Codes: H04R 2201/401 2D or 3D arrays of transducers
• CPC Class Codes: H04R 2205/022 Plurality of transducers corresponding to a plurality of sound channels in each earpiece of headphones or in a single enclosure
• CPC Class Codes: H04R 2430/20 Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic H04R2203/12 takes precedence
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04S 3/00 Systems employing more than two channels, e.g. quadraphonic H04S5/00, H04S7/00 take precedence

Abstract

A method and system for surround sound beam-forming using vertically displaced drivers provides a low cost alternative to present external surround array systems. A pair of vertically displaced speaker drivers is supplied with surround and main channel information in a controlled phase relationship with respect to each driver such that the surround channel information is propagated in a directivity pattern substantially differing from that of the main channel information. The main channel information is generally directed at a listening area, while the surround channel information is directed away from the listening area and is substantially attenuated in the direction of the listening area, so that the surround channel information is heard as a diffuse reflected field. An electronic network provides for control of the surround channel phase relationship and combining of main and surround signals for providing inputs to individual power amplifiers for each driver.

Claims

1. A method of audio beam-forming, comprising:

providing a first signal to a first speaker driver, wherein said first signal contains main channel and surround channel information;

providing a second signal to a second speaker driver vertically displaced from said first speaker driver, wherein said second signal contains said main channel information and said surround channel information; and

controlling a phase relationship between said surround channel information within said first signal and said surround channel information within said second signal to control propagation of said main channel and surround channel information in a predetermined direction toward a listening position, wherein said surround channel information is propagated with a first directivity pattern having substantial attenuation in said predetermined direction and at least one lobe having a directivity peak located substantially away from said predetermined direction, and wherein said main channel information is propagated with a second directivity pattern having a substantially peak amplitude in said predetermined direction.

2. The method of claim 1, further comprising controlling a phase relationship between said main channel information within said first signal and said main channel information within said second signal, such that a shape of said second directivity pattern is controlled.

3. The method of claim 1, wherein said controlling a phase relationship is performed by said first providing said surround channel information in a first polarity to said first speaker driver and second providing said surround channel information in an opposing polarity to said second speaker driver in said overlapping frequency range.

4. The method of claim 1, wherein said first and second speaker drivers are mounted in a single speaker cabinet and wherein said method further comprises:

receiving said main channel information via at least one electrical connector on said speaker cabinet; and

receiving said surround channel information via said at least one electrical connector.

5. The method of claim 1, wherein said controlling a phase relationship is performed by calibrating at least one adjustable impulse response filter coupling said surround channel information to said first speaker driver.

6. The method of claim 1, further comprising separating said surround channel information into a low frequency component and a beam-forming component, and wherein said providing a first signal further comprises generating said first signal in conformity with said main channel information and said low frequency component of said surround channel information independent of said controlled phase relationship, and said beam-forming component of said surround channel information as controlled by said controlling a phase relationship.

7. The method of claim 6, further comprising separating said surround channel information into a high frequency component, and wherein said generating said first signal further generates said first signal by:

delaying said high frequency component of said surround channel information; and

combining said high frequency component of said surround channel information in said first signal.

8. A system for audio beam-forming, comprising:

a first speaker driver;

a second speaker driver vertically displaced from said first speaker driver; and

an electronic network for receiving surround channel information and main channel information and supplying a first signal to said first speaker driver and a second signal to said second speaker driver generated in conformity with both said surround channel information and said main channel information, and wherein said electronic network controls a frequency dependent phase relationship between surround channel information in said first signal and said second signal, wherein said surround channel information is propagated with a first directivity pattern having substantial attenuation in said predetermined direction and at least one lobe having a directivity peak located substantially away from said predetermined direction, and wherein said main channel information is propagated with a second directivity pattern having substantially peak amplitude in said predetermined direction.

9. The system of claim 8, further comprising a housing, wherein said first and second speaker drivers are mounted conformal to at least one surface of said housing, and wherein said electronic network is mounted internal to said housing.

10. The system of claim 9, wherein said housing is a housing of a consumer device having at least audio capabilities with surround channel and main channel outputs, and wherein said first speaker driver and said second speaker driver provide a simulated surround field from said consumer device.

11. The system of claim 10, wherein said consumer device is a television.

12. The system of claim 8, wherein said electronic network comprises at least one finite impulse response (FIR) filter for controlling said phase relationship by adjusting a phase of at least said first signal over frequency.

13. The system of claim 8, wherein said electronic network comprises:

at least one first filter for said surround channel information into a low frequency component and a beam-forming component;

a combiner for combining said main channel information, said low frequency component of said surround channel information that is not controlled by said frequency-dependent phase relationship, and said beam-forming component of said surround channel information as controlled by said frequency-dependent phase relationship.

14. The system of claim 13, further comprising:

a second filter for separating said surround channel information into a high frequency component; and

a delay for delaying said high frequency component of said surround channel information, and wherein said combiner further combines said high frequency component of said surround channel information in said first signal.

15. A speaker, comprising:

a cabinet;

a first speaker driver mounted within said cabinet;

a second speaker driver mounted within said cabinet and vertically displaced from said first speaker driver; and

an electronic circuit for receiving a surround channel signal bearing surround channel information and a main channel signal bearing main channel information and supplying a first signal to said first speaker driver and a second signal to said second speaker driver generated in conformity with both said surround channel signal and said main channel signal, and wherein said electronic circuit controls a phase relationship between said surround channel information within said first signal and said surround channel information within said second signal to control propagation of said main channel and surround channel information in a predetermined direction toward a listening position, wherein said surround channel information is propagated with a first directivity pattern having substantial attenuation in said predetermined direction and at least one lobe having a directivity peak located substantially away from said predetermined direction, and wherein said main channel information is propagated with a second directivity pattern having substantially peak amplitude in said predetermined direction.

16. The speaker of claim 15, further comprising at least one connector for receiving said main channel signal and said surround channel signal.

17. The speaker of claim 15, further comprising:

at least one connector for receiving said main channel signal; and

a surround synthesizer circuit for generating said surround channel signal in response to said main channel signal, whereby said speaker provides a simulated surround environment from said main channel signal.

18. A method of audio beam-forming, comprising:

providing a first signal to a first speaker driver, wherein said first signal contains main channel and surround channel information;

providing a second signal to a second speaker driver oriented away from an on-axis direction of said first speaker driver, wherein said second signal contains said surround channel information; and

controlling at least one of an amplitude and phase relationship between said surround channel information within said first signal and said surround channel information within said second signal to control propagation of said surround channel information in a predetermined direction toward a listening position, wherein said surround channel information is propagated with a first directivity pattern having substantial attenuation in said predetermined direction and at least one lobe having a directivity peak located substantially away from said predetermined direction, and wherein said main channel information is propagated with a second directivity pattern having substantially peak amplitude in said predetermined direction.

19. The method of claim 18, wherein said controlling adjusts an amplitude of inverted surround channel information supplied in said first signal, whereby said attenuation can be maximized.

20. The method of claim 18, wherein said second signal further contains said main channel information.

21. The method of claim 18, further comprising providing an orientable mechanical coupling between said first speaker driver and said second speaker driver, whereby said second speaker driver may be selectively oriented away from said on-axis direction of said first speaker driver.

22. The method of claim 21, wherein said providing an orientable mechanical coupling comprises coupling a first speaker cabinet portion housing said first speaker driver within a second speaker cabinet portion housing said second speaker driver.

23. The method of claim 22, wherein said providing an orientable mechanical coupling comprises connecting said first speaker cabinet portion with said second speaker cabinet portion via a rotatable linkage.

24. A system for audio beam-forming, comprising:

a first speaker driver;

a second speaker driver oriented away from an on-axis direction of said first speaker driver; and

an electronic network for receiving surround channel information and main channel information and supplying a first signal to said first speaker driver generated in conformity with both said surround channel information and said main channel information, and providing a second signal generated in conformity with said surround channel information to said second speaker, and wherein said electronic network controls at least one of a frequency dependent amplitude and phase relationship between surround channel information in said first signal and said second signal, wherein said surround channel information is propagated with a first directivity pattern having substantial attenuation in said predetermined direction and at least one lobe having a directivity peak located substantially away from said on-axis direction.

25. The system of claim 24, wherein said electronic network comprises a variable gain circuit for adjusting an amplitude of inverted surround channel information supplied in said first signal, whereby said attenuation can be maximized.

26. The system of claim 24, wherein said electronic network further generates said second signal in conformity with said main channel information.

27. The system of claim 24, further comprising:

a first speaker cabinet portion housing said first speaker driver;

a second speaker cabinet portion housing said second speaker driver; and

an orientable mechanical coupling between said first speaker cabinet portion and said second speaker cabinet portion, whereby said second speaker driver may be selectively oriented away from said on-axis direction of said first speaker driver.

28. The system of claim 27, further comprising a rotatable linkage mechanically connecting said first and second speaker cabinet portions.

29. A system for audio beam-forming, comprising:

a first speaker driver mounted in a first cabinet;

a second speaker driver mounted in a second cabinet; and

an electronic network for receiving surround channel information and main channel information and supplying a first signal to said first speaker driver and a second signal to said second speaker driver generated in conformity with both said surround channel information and said main channel information, and wherein said electronic network controls a frequency dependent phase relationship between surround channel information in said first signal and said second signal, wherein said surround channel information is propagated with a first directivity pattern having substantial attenuation in said predetermined direction and at least one lobe having a directivity peak located substantially away from said predetermined direction, and wherein said main channel information is propagated with a second directivity pattern having substantially peak amplitude in said predetermined direction.

30. The system of claim 29, wherein said electronic network has a selectable operating mode, wherein in a first operating mode, said electronic network generates said first signal and said second signal in conformity with both said main channel information and said surround channel information, whereby said system is adapted to operate as a simulated surround system when said first and second cabinets are located at the same end of a listening room, and wherein in a second operating mode, said electronic network generates said first signal only in conformity with said surround channel information and said second signal only in conformity with said main channel information, whereby said system is adapted for use as an ordinary surround sound system when said first cabinet and said second cabinet are positioned at opposite ends of a listening room.