Optimal sonic separator and multi-channel forward imaging system

• US 5,119,422 A
• Filed: 10/01/1990
• Issued: 06/02/1992
• Est. Priority Date: 10/01/1990
• Status: Expired due to Fees

• Current Assignee: David A. Price
• Original Assignee: David A. Price
• Inventors: Price, David A.
• Primary Examiner(s): Isen, Forester W.
• Application Number:
  US07/591,130
• Time in Patent Office: 610 Days
• Field of Search: 381/1, 381/17, 381/24
• US Class Current: 381/303
• CPC Class Codes: H04S 5/005 of the pseudo five- or more-channel type, e.g. virtual surround

Abstract

A method and system for separating and "unmixing" prerecorded and mixed right and left stereo sound input signals into three (3) or more output sound signals for sound reproduction by three or more loudspeakers spaced apart and located forward of a listener or listeners. The output sound signals are linear combinations of the right and left sound input signals and uniquely satisfy conditions of sound linearity, symmetry, uniformity, normality, integrity, balance, constancy, and fidelity to create a substantially more accurate sound image of the recorded performance than that created by reproducing only the stereophonic sound input signals.

Claims

1. An improved forward sound imaging system, comprising:

first and second inputs for receiving left and right channel audio input signals of a stereophonic system;

a plurality of n, n being any whole number greater than three, output channels for connection to n loudspeakers spaced symmetrically left to right and forward of a listening position; and

a plurality of n independent means, each responsive to said left and right audio input signals for developing a first through n-th audio output signal proportional to a sum of a product of a first through n-th coefficient and the left audio input signal and a product of the n-th through first coefficient and the right audio input signal, in a first through n-th one of the output channels, respectively; and

wherein;

1is greater than the first coefficient;

each of the second through (n-1-th coefficients is less than the first through (n-2)-th coefficient, respectively;

the (n-1)-th coefficient is greater than 0; and

the n-th coefficient is less than 0 and greater than the negative of the first coefficient.

2. The system of claim 1, wherein:

n is less than 9; and

for n=4

the first coefficient is between 0.80 and 0.83,

the second coefficient is between 0.43 and 0.50,

the third coefficient is between 0.28 and 0.31, and

the fourth coefficient is between -0.18 and -0.16,

for n=5

the first coefficient is between 0.74 and 0.78,

the second coefficient is between 0.42 and 0.49,

the third coefficient is between 0.33 and 0.35,

the fourth coefficient is between 0.20 and 0.25, and

the fifth coefficient is between -0.22 and -0.20,

for n=6

the first coefficient is between 0.70 and 0.75,

the second coefficient is between 0.40 and 0.47,

the third coefficient is between 0.33 and 0.37.

the fourth coefficient is between 0.26 and 0.28,

the fifth coefficient is between 0.15 and 0.21, and

the sixth coefficient is between -0.25 and -0.23,

for n=7

the first coefficient is between 0.66 and 0.72,

the second coefficient is between 0.38 and 0.45,

the third coefficient is between 0.33 and 0.38,

the fourth coefficient is between 0.28 and 0.30,

the fifth coefficient is between 0.21 and 0.24,

the sixth coefficient is between 0.12 and 0.18, and

the seventh coefficient is between -0.27 and -0.25,

for n=8

the first coefficient is between 0.63 and 0.69,

the second coefficient is between 0.37 and 0.44,

the third coefficient is between 0.32 and 0.37,

the fourth coefficient is between 0.28 and 0.31,

the fifth coefficient is between 0.24 and 0.25,

the sixth coefficient is between 0.17 and 0.21,

the seventh coefficient is between 0.09 and 0.16, and

the eighth coefficient is between -0.29 and -0.27.

3. The system of claim 1, wherein:

n is less than 9;

and

for n=4

the first coefficient is within 0.01 of 0.80,

the second coefficient is within 0.01 of 0.49,

the third coefficient is within 0.01 of 0.28, and

the fourth coefficient is within 0.01 of -0.17,

for n=5

the first coefficient is within 0.01 of 0.75,

the second coefficient is within 0.01 of 0.49,

the third coefficient is within 0.01 of 0.35,

the fourth coefficient is within 0.01 of 0.20, and

the fifth coefficient is within 0.01 of -0.21,

for n=6

the first coefficient is within 0.01 of 0.70,

the second coefficient is within 0.01 of 0.47,

the third coefficient is within 0.01 of 0.37,

the fourth coefficient is within 0.01 of 0.27,

the fifth coefficient is within 0.01 of 0.15, and

the sixth coefficient is within 0.01 of -0.24,

for n=7

the first coefficient is within 0.01 of 0.66,

the second coefficient is within 0.01 of 0.45,

the third coefficient is within 0.01 of 0.37,

the fourth coefficient is within 0.01 of 0.30,

the fifth coefficient is within 0.01 of 0.21,

the sixth coefficient is within 0.01 of 0.12, and

the seventh coefficient is within 0.01 of -0.27,

for n=8

the first coefficient is within 0.01 of 0.63,

the second coefficient is within 0.01 of 0.43,

the third coefficient is within 0.01 of 0.37,

the fourth coefficient is within 0.01 of 0.31,

the fifth coefficient is within 0.01 of 0.24,

the sixth coefficient is within 0.01 of 0.18,

the seventh coefficient is within 0.01 of 0.10, and

the eighth coefficient is within 0.01 of -0.29.

4. The system of claim 1, wherein n=4.

5. The system of claim 2, wherein n=4.

6. The system of claim 3, wherein n=4.

7. The system of claim 1, wherein n=5.

8. The system of claim 2, wherein n=5.

9. The system of claim 3, wherein n=5.

10. The system of claim 1, wherein n=6.

11. The system of claim 2, wherein n=6.

12. The system of claim 3, wherein n=6.

13. The system of claim 1, wherein n=7.

14. The system of claim 2, wherein n=7.

15. The system of claim 3, wherein n=7.

16. The system of claim 1, wherein n=8.

17. The system of claim 2, wherein n=8.

18. The system of claim 3, wherein n=8.

19. An improved forward sound imaging system, comprising:

first and second inputs for receiving left and right channel audio input signals of a stereophonic system;

a plurality of three output channels for connection to three loudspeakers spaced symmetrically left to right and forward of a listening position; and

a plurality of three independent means, each responsive to said left and right audio input signals for developing a first through third audio output signal proportional to a sum of a product of a first through third coefficient and the left audio input signal and a product of the third through first coefficient and the right audio input signal, in a first through third one of the output channels, respectively; and

wherein;

1is greater than the first coefficient

the second coefficient is less than the first coefficient and greater than 0; and

the third coefficient is less than 0 and greater than the negative of the first coefficient.

20. An improved forward sound imaging system comprising:

first and second inputs for receiving left and right channel audio input signals of a stereophonic system;

a plurality of three output channels for connection to three loudspeakers spaced symmetrically left to right and forward of a listening position; and

a plurality of three independent means, each responsive to said left and right audio input signals for developing a first through third audio output signal proportional to a sum of a product of a first through third coefficient and the left audio input signal and a product of the third through first coefficient and the right audio input signal, in a first through third one of the output channels, respectively; and

wherein;

the first coefficient is between 0.88 and 0.90,

the second coefficient is between 0.43 and 0.46, and

the third coefficient is between -0.12 and -0.10.

21. An improved forward sound imaging system, comprising:

first and second inputs for receiving left and right channel audio input signals of a stereophonic system;

a plurality of three output channels for connection to three loudspeakers spaced symmetrically left to right and forward of a listening position; and

a plurality of three independent means, each responsive to said left and right audio input signals for developing a first through third audio output signal proportional to a sum of a product of a first through third coefficient and the left audio input signal and a product of the third through first coefficient and the right audio input signal, in a first through third one of the output channels, respectively; and

wherein;

the first coefficient is within 0.01 of 0.88,

the second coefficient is within 0.01 of 0.45, and

the third coefficient is within 0.01 of -0.12.