SYSTEM AND METHOD FOR DIRECTIONALLY RADIATING SOUND

• US 20080273723A1
• Filed: 07/19/2007
• Published: 11/06/2008
• Est. Priority Date: 05/04/2007
• Status: Active Grant

• Current Assignee: Bose Corporation
• Original Assignee: Bose Corporation
• Inventors: Hartung, Klaus, Hultz, Paul B.
• Granted Patent: US 9,100,748 B2
• Time in Patent Office: Days
• US Class Current: 381/302
• CPC Class Codes: H04R 1/403 loud-speakers
• 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 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04R 5/023 in a chair, pillow
• CPC Class Codes: H04S 3/00 Systems employing more than two channels, e.g. quadraphonic H04S5/00, H04S7/00 take precedence
• CPC Class Codes: H04S 7/30 Control circuits for electronic adaptation of the sound field

Abstract

A method of operating an audio system that provides audio radiation to a plurality of listening positions includes providing at least one source of audio signals. At each listening position, at least one array of speaker elements is provided. A filter is provided between the at least one source and at least one of the speaker elements at a first listening position. The filter is optimized so that the filter reduces acoustic energy radiated from the first array to at least one other listening position of the plurality of listening positions, compared to acoustic energy radiated from the first array to the first listening position.

Claims

1. A method of operating an audio system that provides audio radiation to a plurality of listening positions, the method comprising the steps of:

(a) providing at least one source of audio signals;

(b) providing, at each listening position, at least one array of speaker elements that receives the audio signals and responsively radiates output audio signals, wherein the speaker elements of the at least one array are disposed with respect to each other so that the output audio signals radiated from respective said speaker elements destructively interfere to thereby define a directional audio radiation from the at least one array;

(c) providing a filter between the at least one source and at least one of the speaker elements in a first said array at a first listening position of the plurality of listening positions, wherein the filter processes magnitude and phase of the audio signals from the at least one source to the at least one speaker element; and

(d) optimizing the filter so that the filter reduces a magnitude of acoustic energy radiated from the first array to at least one other listening position of the plurality of listening positions, compared to a magnitude of acoustic energy radiated from the first array to the first listening position.

2. The method as in claim 1, including providing a said first array at each listening position of the plurality of listening positions.

3. The method as in claim 2, including providing a plurality of said first arrays at each listening position of the plurality of listening positions.

4. The method as in claim 1, wherein the first array is comprised of a first said speaker element and at least one second said speaker element, and wherein step (c) includes providing a said filter between the at least one source and each said second speaker element.

5. The method as in claim 1, wherein step (d) comprises optimizing the filter so that the filter reduces a magnitude of acoustic energy radiated from the first array to an acoustically reflective surface near the first listening position, compared to a magnitude of acoustic energy radiated from the first array to the first listening position.

6. The method as in claim 1, wherein step (d) comprises the steps of

(d1) driving each of the speaker elements in the first array to radiate first said output audio signals,

(d2) detecting the first output audio signals at the first listening position and at the at least one other listening position,

(d3) determining a first transfer function between the first output audio signals detected at the first listening position and the audio signals from the at least one source,

(d4) determining a second transfer function between the first output audio signals detected at the at least one other listening position and the audio signals from the at least one source,

(d5) defining a cost function that compares the first transfer function and the second transfer function,

(d6) determining a gradient of the cost function that defines a direction toward reduction of the cost function,

(d7) modifying the filter according to the direction, and

(d8) repeating steps (d1) to (d7) until step (d6) meets a predetermined criteria.

7. The method as in claim 2, comprising the step (e) detecting whether an occupant is present at each of the listening positions, and wherein step (d) comprises, for each said first array, optimizing the filter so that the filter reduces the magnitude of acoustic energy radiated from the first array to the at least one other listening position of the plurality of listening positions, compared to the magnitude of acoustic energy radiated from the first array to the first listening position, only if an occupant is present at the at least one other listening position of the plurality of listening positions.

8. The method as in claim 2, comprising the step (e) detecting whether each said at least one array receives audio signals from the at least one source that is same as or different from audio signals from the at least one source received by the other at least one arrays at the other said listening positions, and wherein step (d) comprises, for each said first array, optimizing the filter so that the filter reduces the magnitude of acoustic energy radiated from the first array to the at least one other listening position of the plurality of listening positions, compared to the magnitude of acoustic energy radiated from the first array to the first listening position, only if the audio signals received from the audio source by the at least one array at the first listening position are different than the audio signals received from the audio source by the at least one array at the at least one other listening position of the plurality of listening positions.

9. The method as in claim 2,

comprising the step (e) detecting whether each said at least one array receives audio signals from the at least one source that is same as or different from audio signals from the at least one source received by the other at least one arrays at the other said listening positions

comprising the step (f) detecting whether an occupant is present at each of the listening positions, and

wherein step (d) comprises, for each said first array, optimizing the filter so that the filter reduces the magnitude of acoustic energy radiated from the first array to the at least one other listening position of the plurality of listening positions, compared to the magnitude of acoustic energy radiated from the first array to the first listening position, only if an occupant is present at the at least one other listening position of the plurality of listening positions and if the audio signals received from the audio source by the at least one array at the first listening position are different than the audio signals received from the audio source by the at least one array at the at least one other listening position of the plurality of listening positions.

10. The method of claim 1, wherein the plurality of listening positions are in a vehicle, wherein each listening position is a seat position in the vehicle, and step (a) comprises providing the at least one source of audio signals in the vehicle.

11. A method of operating an audio system that provides audio radiation to a plurality of listening positions, the method comprising the steps of:

(a) providing at least one source of audio signals;

(b) providing, at each listening position, at least one array of speaker elements that receives the audio signals and responsively radiates output audio signals, wherein the speaker elements of the at least one array are disposed with respect to each other so that the output audio signals radiated from respective said speaker elements destructively interfere to thereby define a directional audio radiation from the at least one array;

(c) providing, at a first said at least one array of each first listening position of the plurality of listening positions, a first filter between the at least one source and at least one of the speaker elements in the first array, wherein the first filter processes magnitude and phase of the audio signals from the at least one source to the at least one speaker element;

(d) optimizing the first filter so that the first filter reduces a magnitude of acoustic energy radiated from the first array to at least one other listening position of the plurality of listening positions, compared to a magnitude of acoustic energy radiated from the first array to the first listening position;

(e) providing, between each said first array and a second said at least one array of each other second said listening position, a second filter between first said audio signals and the second array so that the second array receives the first audio signals through the filter and responsively radiates output audio signals, wherein the first audio signals are received by the first array and wherein the first array receives the first audio signals independently of the second filter; and

(f) defining a transfer function that characterizes the second filter so that the second filter processes magnitude and phase of the first audio signals so that a combined magnitude of acoustic energy radiated to the second listening position by the second array responsively to the first audio signals and acoustic energy radiated to the second listening position by the first array responsively to the first audio signals is less than the acoustic energy radiated to the second listening position by the first array responsively to the first audio signals.

12. The method as in claim 11, wherein step (f) comprises optimizing the transfer function that characterizes the second filter so that the second filter reduces a magnitude of combined acoustic energy radiated to the second listening position by the first array and the second array responsively to the first audio signals, compared to a magnitude of acoustic energy radiated to the first listening position by the first array and the second array responsively to the first audio signals.

13. The method of claim 11, wherein the plurality of listening positions are in a vehicle, wherein each listening position is a seat position in the vehicle, and step (a) comprises providing the at least one source of audio signals in the vehicle.

14. A method of operating an audio system that provides audio radiation to a plurality of listening positions, the method comprising the steps of:

(a) providing at least one source of audio signals;

(b) providing, at each listening position, a speaker that receives the audio signals and responsively radiates output audio signals, wherein a first said speaker at a first said listening position receives first said audio signals;

(c) providing a filter between the first audio signals and a second said speaker at a second said listening position so that the second speaker receives the first audio signals through the filter and responsively radiates output audio signals, wherein the first speaker receives the first audio signals independently of the filter;

(d) defining a transfer function that characterizes the filter so that the filter processes magnitude and phase of the first audio signals provided to the second speaker so that a combined magnitude of acoustic energy radiated to the second listening position by the second speaker responsively to the first audio signals and acoustic energy radiated to the second listening position by the first speaker responsively to the first audio signals is less than the acoustic energy radiated to the second listening position by the first speaker responsively to the first audio signals.

15. The method as in claim 14, wherein step (d) comprises optimizing the transfer function so that the filter reduces a magnitude of combined acoustic energy radiated to the second listening position by the first speaker and the second speaker responsively to the first audio signals, compared to a magnitude of acoustic energy radiated to the first listening position by the first speaker and the second speaker responsively to the first audio signals.

16. The method as in claim 14, wherein step (d) comprises

(d1) determining a first transfer function between the first audio signals and output audio signals radiated to the second listening position by the first speaker,

(d2) determining a second transfer function between the first audio signals and output audio signals radiated to the second listening position by the second speaker,

(d3) determining a third transfer function corresponding to a ratio between the first transfer function and the second transfer function, and

(d4) defining the transfer function that characterizes the filter so that the filter processes the magnitude and phase of the first audio signals provided to the second speaker according to a function corresponding in magnitude, and out of phase with, the third transfer function.

17. The method as in claim 16, wherein the transfer function defined at step (d4) is out of phase by about 180 degrees with respect to the transfer function determined at step (d3).

18. An audio system for a vehicle having a plurality of seat positions, said audio system comprising:

at least one source of audio signals;

a respective directional loudspeaker array mounted at each seat position and coupled to the at least one source so that the audio signals drive the respective directional loudspeaker array to radiate acoustic energy;

processing circuitry between the at least one source and each said respective directional loudspeaker array, wherein the processing circuitry respectively processes magnitude and phase of the audio signals from the at least one source to each said respective directional loudspeaker array so that each respective directional loudspeaker array directionally radiates acoustic energy to the seat position at which it is located and so that a magnitude of acoustic energy radiated from said respective directional array to each other said seat position is below a level that is perceptible by a respective listener at each other seat position when at least one respective directional loudspeaker at the other seat position radiates acoustic energy to the other seat position.

19. The system as in claim 18, wherein the magnitude of acoustic energy radiated from said respective directional array to each other said seat position is at least about 10 dB lower than a magnitude of the acoustic energy radiated from the respective directional loudspeaker to the seat position at which it is located, over a predetermined frequency range.

20. An audio system for a vehicle having a plurality of seat positions, said audio system comprising:

at least one source of audio signals;

a respective directional loudspeaker array mounted at each seat position and coupled to the at least one source so that the audio signals drive the respective directional loudspeaker array to radiate acoustic energy;

processing circuitry between the at least one source and each said respective directional loudspeaker array, wherein the processing circuitry respectively processes magnitude and phase of the audio signals from the at least one source to each said respective directional loudspeaker array so that each respective directional loudspeaker array directionally radiates acoustic energy to the seat position at which it is located in a high radiation direction and radiates acoustic energy to each other said seat position in a low radiation direction.

21. A method of operating an audio system that provides audio radiation to a plurality of seat positions in a vehicle, the method comprising the steps of:

(a) providing at least one source of audio signals;

(b) providing, at each seat position, at least one array of speaker elements that receives the audio signals and responsively radiates output audio signals, wherein the speaker elements of the at least one array are disposed with respect to each other so that the output audio signals radiated from respective said speaker elements destructively interfere to thereby define a directional audio radiation from the at least one array;

(c) providing a filter between the at least one source and at least one of the speaker elements in a first said array at a first seat position of the plurality of seat positions, wherein the filter processes magnitude and phase of the audio signals from the at least one source to the at least one speaker element; and

(d) selecting the filter based on a predetermined relationship between a magnitude of acoustic energy radiated from the first array to at least one other seat position of the plurality of seat positions and a magnitude of acoustic energy radiated from the first array to the first seat position.

22. The method as in claim 21, comprising the steps (e) determining a state of a predetermined criteria for each seat position of the plurality of seat positions other than the first seat position and (f) selecting at least one seat position other than the first seat position based on the state of the criteria determined at step (e), and wherein step (d) comprises, for each said first array, selecting the filter based on the predetermined relationship between the magnitude of acoustic energy radiated from the first array to each seat position selected at step (f) and the magnitude of acoustic energy radiated from the first array to the first seat position.

23. The method as in claim 21, comprising the step (e) detecting whether an occupant is present at each of the seat positions, and wherein step (d) comprises, for each said first array, selecting the filter based on the predetermined relationship between the magnitude of acoustic energy radiated from the first array to the at least one other seat position and a magnitude of acoustic energy radiated from the first array to the first seat position, only if an occupant is present at the at least one other seat position.

24. The method as in claim 21, comprising the step (e) detecting whether each said at least one array receives audio signals from the at least one source that is same as or different from audio signals from the at least one source received by the other at least one arrays at the other said seat positions, and wherein step (d) comprises, selecting the filter based on the predetermined relationship between the magnitude of acoustic energy radiated from the first array to the at least one other seat position and a magnitude of acoustic energy radiated from the first array to the first seat position, only if the audio signals received from the audio source by the at least one array at the first seat position are different than the audio signals received from the audio source by the at least one array at the at least one other seat position of the plurality of seat positions.

25. An audio system for a vehicle having a plurality of seat positions, said audio system comprising:

at least one source of audio signals;

a respective directional loudspeaker array mounted at each seat position and coupled to the at least one source so that the audio signals drive the respective directional loudspeaker array to radiate acoustic energy;

a sensor in communication with each seat position so that the sensor outputs signals respectively indicating whether an occupant is present in each said seat position;

control circuitry that receives the signals output by the sensor and identifies at which seat positions of the plurality of seat positions an occupant is present responsively to the signals output by the sensor;

processing circuitry between the at least one source and each said respective directional loudspeaker array, wherein, responsively to the control circuitry, the processing circuitry respectively processes magnitude and phase of the audio signals from the at least one source to each said respective directional loudspeaker array so that each respective directional loudspeaker array directionally radiates acoustic energy having a first magnitude to the seat position at which it is located and selectively radiates to at least one other said seat position acoustic energy having a magnitude below the first magnitude according to a predetermined criteria, depending upon whether the signals output by the sensor indicate that an occupant is present at the at least one other seat position.