Acoustic Spatial Projector

• US 20120263306A1
• Filed: 04/18/2011
• Published: 10/18/2012
• Est. Priority Date: 04/18/2011
• Status: Active Grant

• Current Assignee: Paul Blair Mcgowan
• Original Assignee: Paul Blair Mcgowan
• Inventors: McGowan, Paul Blair
• Granted Patent: US 8,867,749 B2
• Time in Patent Office: Days
• US Class Current: 381/17
• CPC Class Codes: H04R 1/403 loud-speakers
• CPC Class Codes: H04R 2203/12 Beamforming aspects for stereophonic sound reproduction with loudspeaker arrays
• 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 5/00 Stereophonic arrangements stereophonic pick-ups H04R9/16, H04R11/12, H04R17/08, H04R19/10

Abstract

A method and system for producing an acoustic spatial projection by creating audio channels for producing an acoustic field by mixing, on a reflective surface, sounds associated with the audio channels is provided. In one embodiment, a method includes the step of using audio information to determining a set of audio channels. Each audio channel is associated with a sound source, such as one or more loudspeakers, and for a subset of the audio channels, the associated sound sources emit sound waves directed at a reflective surface prior to being received at a listening location. The method further includes steps of determining an acoustic response of a listening environment; steps of determining a delay to apply to one or more channels of the set of audio channels; and steps of determining a frequency compensation to apply to one or more channels of the audio channels.

Claims

1. Computer-readable media having computer-executable instructions embodied thereon that when executed, facilitate a method for creating audio channels for producing an acoustic field by mixing, on a reflective surface, sounds associated with the audio channels, the method comprising:

(a) using audio information, determining a set of audio channels, wherein each channel is associated with a sound source, and wherein the set of audio channels includes a first subset of channels and a second subset of channels, wherein each audio channel of the first subset of audio channels has an associated sound source that emits sound waves directed at a reflective surface prior to being received at a listening location;

(b) determining a first delay to apply to a first channel of the set of audio channels, wherein the first delay is determined as a function of an estimated duration of time for sound waves emitted by a first sound source associated with the first channel to reach the listening location; and

(c) determining a frequency compensation to apply to at least one channel of the second subset of audio channels, wherein the frequency compensation is based on a model acoustic response that includes information relating to at least one of amplitude, timing, phase response, or frequency response.

2. The computer-readable media of claim 1 wherein the frequency compensation comprises at least one of:

(i) attenuating or boosting a first range of frequencies of the at least one channel of the second subset of channels, or

(ii) applying a frequency-based delay to a second range of frequencies of the at least one channel of the second subset of channels.

3. The computer-readable media of claim 1 wherein the first subset of audio channels includes a left-back channel associated with a left-back sound source directionally positioned towards the reflective surface at a first angle, a right-back channel associated with a right-back sound source directionally positioned towards the reflective surface at a second angle, and a center-back channel associated with a center-back sound source directionally positioned to substantially face the reflective surface.

4. The computer-readable media of claim 3 wherein the first angle approximately equals the negative of the second angle.

5. The computer-readable media of claim 3 wherein the audio information includes a left-channel component and right-channel component;

and wherein the set of audio channels is determined such that the left-back channel represents a first combination of the left-channel component and the right-channel component, and the right-back channel represents a second combination of the left-channel component and the right-channel component.

6. The computer-readable media of claim 5 wherein the first combination is determined by calculating a difference between the left-channel component, multiplied by a predefined factor, and the right-channel component, and the second combination is determined by calculating a difference between the right-channel component, multiplied by a the predefined factor, and the left-channel component.

7. The computer-readable media of claim 3 wherein the method further comprises determining a second delay,

wherein the set of audio channels includes a center-front channel associated with a center-front sound source directionally positioned to substantially face the listening area;

wherein the second delay is applied to the center-front channel of the set of audio channels, and the first delay is applied to the center-back channel of the set of audio channels; and

wherein the second delay is determined as a function of an estimated duration of time for sound waves emitted by the center-front sound source to reach the listening location.

8. The computer-readable media of claim 7 wherein the first and second delays are further determined such that sound waves emitted by each of the left-back sound source, center-back sound source, right-back sound source, and center-front sound source will reach the listening location at substantially the same time.

9. The computer-readable media of claim 1 wherein the method for determining the frequency compensation further comprises:

for the at least one audio channel of the second subset of audio channels;

(i) providing an audio signal having predefined characteristics of frequency, amplitude, or duration, thereby resulting in sound waves being emitted from the at least on audio channel'"'"'s associated sound source;

(ii) receiving acoustic-response information corresponding to the sound waves;

(iii) comparing the received acoustic-response information to information in the model acoustic response;

(iv) based on the comparison, determining the frequency-compensation for the at least one audio channel; and

(v) storing information representing the frequency-compensation for the at least one audio channel.

10. The computer-readable media of claim 9 wherein frequency compensation is determined and applied to each audio channel of the second subset of audio channels.

11. The computer-readable media of claim 9 wherein determining the frequency compensation further comprises:

(a) Substantially simultaneously providing a distinct audio signal on each channel of the second subset of the set of audio channels, each distinct signal having predefined characteristics of frequency, amplitude, or duration, thereby resulting in an emission of sound waves from each sound source associated with each channel of the second subset of channels;

(b) receiving combined acoustic-response information;

(c) comparing the received combined-acoustic-response information to information in the model acoustic response;

(d) based on the comparison of the received combined acoustic-response information to information in the model and the stored frequency-compensation for the at least one audio channel of the second subset of audio channels, determining an updated frequency-compensation for the at least one audio channel of the second subset of audio channels; and

(e) storing information representing the updated frequency-compensation for the at least one audio channel of the second subset of audio channels.

12. The computer-readable media of claim 1 wherein the audio information includes information corresponding to volume, and wherein an output volume is determined to apply to one or more audio channels of the set of audio channels, such that the output volume increases nonlinearly with respect to increases in volume of the audio information.

13. A method for creating audio channels for producing an acoustic field by mixing sound waves associated with the audio channels on a reflective surface, the method comprising:

(a) using audio information, determining a set of audio channels, wherein each channel is associated with a sound source, and wherein the set of audio channels includes a first subset of channels and a second subset of channels, wherein each audio channel of the first subset of audio channels has an associated sound source that emits sound waves directed at a reflective surface prior to being received at a listening location;

(b) determining a first delay to apply to a first channel of the set of audio channels, wherein the first delay is determined as a function of an estimated duration of time for sound waves emitted by a first sound source associated with the first channel to reach the listening location; and

(c) determining a frequency compensation to apply to at least one channel of the second subset of audio channels, wherein the frequency compensation is based on a model acoustic response that includes information relating to at least one of amplitude, timing, phase response, or frequency response.

14. The method of claim 13 wherein the frequency compensation comprises at least one of:

(i) attenuating or boosting a first range of frequencies of the at least one channel of the second subset of channels, or

(ii) applying a frequency-based delay to a second range of frequencies of the at least one channel of the second subset of channels.

15. The method of claim 13 wherein the first subset of audio channels includes a left-back channel associated with a left-back sound source directionally positioned towards the reflective surface at a first angle, a right-back channel associated with a right-back sound source directionally positioned towards the reflective surface at a second angle, and a center-back channel associated with a center-back sound source directionally positioned to substantially face the reflective surface.

16. The method of claim 15 further comprising determining a second delay,

wherein the set of audio channels further includes a center-front channel associated with a center-front sound source directionally positioned to substantially face the listening area;

wherein the second delay is applied to the center-front channel of the set of audio channels, and the first delay is applied to the center-back channel of the set of audio channels; and

wherein the second delay is determined as a function of an estimated duration of time for sound waves emitted by the center-front sound source to reach the listening location.

17. The method of claim 13 wherein determining the frequency compensation further comprises:

for the at least one audio channel of the second subset of audio channels;

(i) providing an audio signal having predefined characteristics of frequency, amplitude, or duration, thereby resulting in sound waves being emitted from the at least on audio channel'"'"'s associated sound source;

(ii) receiving acoustic-response information corresponding to the sound waves;

(iii) comparing the received acoustic-response information to information in the model acoustic response;

(iv) based on the comparison, determining the frequency-compensation for the at least one audio channel; and

(v) storing information representing the frequency-compensation for the at least one audio channel.

18. The method of claim 17 wherein determining the frequency compensation further comprises:

(a) Substantially simultaneously providing a distinct audio signal on each channel of the second subset of the set of audio channels, each distinct signal having predefined characteristics of frequency, amplitude, or duration, thereby resulting in the emission of sound waves from each sound source associated with each channel of the second subset of channels;

(b) receiving combined acoustic-response information;

(c) comparing the received combined-acoustic-response information to information in the model acoustic response;

(d) based on the comparison of the received combined acoustic-response information to information in the model and the stored frequency-compensation for the at least one audio channel of the second subset of audio channels, determining an updated frequency-compensation for the at least one audio channel of the second subset of audio channels; and

(e) storing information representing the updated frequency-compensation for the at least one audio channel of the second subset of audio channels.

19. A system for use in producing a three-dimensional acoustic field by mixing sounds associated with audio channels on a reflective surface, the system comprising:

one or more processors that execute instructions for facilitating a method of creating audio channels for producing an acoustic field by mixing sounds associated with the audio channels on a reflective surface, the method comprising;

(i) using audio information, determining a set of audio channels, wherein each channel is associated with a sound source, and wherein the set of audio channels includes a first subset of channels and a second subset of channels, wherein each audio channel of the first subset of audio channels has an associated sound source that emits sound waves directed at a reflective surface prior to being received at a listening location;

(ii) determining a first delay to apply to a first channel of the set of audio channels, wherein the first delay is determined as a function of an estimated duration of time for sound waves emitted by a first sound source associated with the first channel to reach the listening location; and

(iii) determining a frequency compensation to apply to at least one channel of the second subset of audio channels, wherein the frequency compensation is based on a model acoustic response that includes information relating to at least one of amplitude, timing, phase response, or frequency response.

20. The system of claim 19 wherein the system further comprises an enclosure containing:

at least three sound sources including a left-back sound source directionally positioned towards the reflective surface at a first angle, a right-back sound source directionally positioned towards the reflective surface at a second angle, such that the second angle approximately equals the negative of the first angle, and a center-back sound source directionally positioned to substantially face the reflective surface; and

wherein the first subset of audio channels includes a left-back channel associated with the left-back sound source, a right-back channel associated with the right-back sound source, and a center-back channel associated with the center-back sound source.