Audio enhancement system for use in a surround sound environment

• US 5,970,152 A
• Filed: 04/30/1996
• Issued: 10/19/1999
• Est. Priority Date: 04/30/1996
• Status: Expired due to Term

• Current Assignee: DTS, Inc. (Adeia, Inc.)
• Original Assignee: SRS Labs Incorporated (Adeia, Inc.)
• Inventors: Klayman, Arnold I.
• Primary Examiner(s): CHIN, VIVIAN C
• Application Number:
  US08/641,319
• Time in Patent Office: 1,267 Days
• Field of Search: 381/27, 381/19, 381/20, 381/21, 381/22, 381/23, 381/1, 381/17, 381/18
• US Class Current: 381/1
• CPC Class Codes: H04S 3/002 Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution control circuits for electronic adaptation of the sound field H04S7/30

Abstract

An audio enhancement system and method for use in a surround sound environment creates a more diffuse and continuous sound field from a multi-channel, multi-speaker reproduction environment. Multiple audio source signals generated from an audio recording, which are intended for speakers placed in front of and behind a listener, are isolated into pairs and processed to create corresponding pairs of component audio signals. Each pair of component audio signals is generated, at least in part, from the information present in both corresponding audio source signals. The individual component audio signals are then selectively combined to form enhanced output signals so that each enhanced output signal is modified as function of a plurality of audio source signals.

Claims

1. An audio enhancement device which broadens the perceived spatial image of sound signals in a surround sound environment, said audio enhancement system comprising:

a left-front audio signal;

a right-front audio signal;

a left-rear audio signal;

a right-rear audio signal;

a front enhancer in communication with said left-front audio signal and said right-front audio signal, said front enhancer configured to modify the ambient information in said left-front audio signal and said right-front audio signal in a manner which generates a plurality of front component signals;

a left enhancer in communication with said left-front audio signal and said left-rear audio signal, said left enhancer configured to modify the ambient information in said left-front audio signal and said left-rear audio signal in a manner which generates a plurality of left component signals;

a rear enhancer in communication with said left-rear audio signal and said right-rear audio signal, said rear enhancer configured to modify the ambient information in said left-rear audio signal and said right-rear audio signal in a manner which generates a plurality of rear component signals;

a right enhancer in communication with said right-rear audio signal and said right-front audio signal, said right enhancer configured to modify the ambient information in said right-rear audio signal and said right-front audio signal in a manner which generates a plurality of right component signals;

a left-front junction configured to combine one of said left component signals and one of said front component signals to generate a left-front output signal;

a left-rear junction configured to combine one of said left component signals and one of said rear component signals to generate a left-rear output signal;

a right-rear junction configured to combine one of said right component signals and one of said rear component signals to generate a right-rear output signal; and

a right-front junction configured to combine one of said right component signals and one of said front component signals to generate a right-front output signal.

2. The audio enhancement device of claim 1 further comprising a first crossover enhancer, said first crossover enhancer in communication with said right-front audio signal and said left-rear audio signal, said first crossover enhancer configured to modify the ambient information in said right-front audio signal and said left-rear audio signal in a manner which generates a first crossover component signal and a second crossover component signal.

3. The audio enhancement device of claim 2 wherein said right-front junction is further configured to combine said first crossover component signal, one of said right component signals and one of said front component signals to generate said right-front output signal.

4. The audio enhancement device of claim 2 wherein said left-rear junction is further configured to combine said second crossover component signal, one of said left component signals and one of said rear component signals to generate said left-rear output signal.

5. The audio enhancement device of claim 2 further comprising a second crossover enhancer, said second crossover enhancer in communication with said left-front audio signal and said right-rear audio signal, said second crossover enhancer configured to modify the ambient information in said left-front audio signal and said right-rear audio signal in a manner which generates a third crossover component signal and a fourth crossover component signal.

6. The audio enhancement device of claim 5 wherein said left-front junction is further configured to combine said third crossover component signal, one of said left component signals and one of said front component signals to generate said left-front output signal.

7. The audio enhancement device of claim 5 wherein said right-rear junction is further configured to combine said fourth crossover component signal, one of said right component signals and one of said rear component signals to generate said right-rear output signal.

8. An audio enhancement device which broadens the perceived spatial image of sound signals, said audio enhancement device comprising:

at least first, second and third audio source signals;

at least two audio enhancers, said first audio enhancer in communication with said first and second audio source signals, said second audio enhancer in communication with said second and third audio source signals, said audio enhancers configured to process information in said pair of audio source signals in a manner which generates a plurality of processed signals; and

at least one combining junction in communication with at least two of said processed signals, said combining junction configured to combine said processed signals to generate at least one output audio signal.

9. The audio enhancement device of claim 8 wherein at least one of said audio enhancers modifies ambient information in said audio signals by inserting a time delay within said ambient information.

10. The audio enhancement device of claim 8 wherein at least one of said audio enhancers modifies ambient information in said audio signals by phase shifting said ambient information.

11. The audio enhancement device of claim 8 wherein at least one of said audio enhancers modifies ambient information in said audio signals by selectively emphasizing relative amplitudes in said ambient information.

12. The audio enhancement device of claim 8 wherein said combining junction adds said processed signals together to generate said plurality of output signals.

13. The audio enhancement device of claim 8 wherein said combining junction comprises an inverting amplifier.

14. The audio enhancement device of claim 8 wherein said combining junction comprises an operational amplifier.

15. A computer system which broadens the perceived spatial image of sound signals, said computer system comprising:

a computer processor configured to access audio data stored on a computer accessible storage medium, said computer processor further configured to transfer said audio data to a data bus;

an audio decoder in communication with said data bus, said audio decoder configured to generate first, second, and third audio source signals;

at least two audio enhancers, said first audio enhancer in communication with said first and second audio source signals, said second audio enhancer in communication with said second and third audio source signals, said audio enhancers configured to modify the information in said audio source signals in a manner which generates a plurality of processed signals; and

at least one combining junction in communication with at least two of said processed signals, said combining junction configured to combine said processed signals to generate at least one output audio signal.

16. The computer system of claim 15 wherein said audio decoder is a digital signal processor.

17. The computer system of claim 15 wherein said audio signals are AC-3 compatible audio signals.

18. The computer system of claim 15 wherein each of said four audio signals corresponds to a discrete, full bandwidth audio channel.

19. The computer system of claim 15 wherein said computer accessible storage medium is a hard disk.

20. The computer system of claim 15 wherein said computer accessible storage medium is a compact disk.

21. the computer system of claim 15 wherein said computer accessible storage medium is a laser disk.

22. An audio enhancement system for use in a surround sound reproduction environment wherein the surround sound environment has at least four separate audio source signals designated for speakers situated within the reproduction environment and placed around a listener, the audio enhancement system modifying the audio source signals to generate at least four enhanced output signals for creating an immersive sound experience for the listener when the enhanced output signals are amplified and played through the speakers, the audio enhancement system comprising:

a first enhancement device receiving a first pair of said audio source signals, said first enhancement device modifying said first pair of source signals to create first and second component signals representative of said first pair of source signals;

a second enhancement device receiving a second pair of said audio source signals, said second enhancement device modifying said second pair of source signals to create third and fourth component signals representative of said second pair of source signals;

a third enhancement device receiving a third pair of said audio source signals, said third enhancement device modifying said third pair of source signals to create fifth and sixth component signals representative of said third pair of source signals;

a fourth enhancement device receiving a fourth pair of said audio source signals, said fourth enhancement device modifying said fourth pair of source signals to create seventh and eighth component signals representative of said fourth pair of source signals;

means for combining said component signals to generate said at least four enhanced output signals for providing an immersive and realistic sound field for a listener, said at least four enhanced output signals comprising;

a first output signal representing a composite of said first component signal and said third component signal;

a second output signal representing a composite of said second component signal and said fifth component signal;

a third output signal representing a composite of said fourth component signal and said seventh component signal; and

a fourth output signal representing a composite of said sixth component signal and said eighth component signal.

23. The audio enhancement system of claim 22 wherein said at least four audio source signals comprise a signal, L_f, designated for a left-front speaker;

a signal, R_f, designated for a right-front speaker;

a signal, L_r, designated for a left-rear speaker; and

a signal, R_R, designated for a right-rear speaker.

24. The audio enhancement system of claim 23 wherein said first pair of source signals comprises the signals L_f and R_f ;

said second pair of source signals comprises the signals L_f and L_r ;

said third pair of source signals comprises the signals R_f and R_r ; and

said fourth pair of source signals comprises the signals L_r and R_r.

25. The audio enhancement system of claim 22 wherein said means for combining said component signals is an electronic adder.

26. The audio enhancement system of claim 22 further comprising:

a fifth enhancement device receiving a fifth pair of said audio source signals, said fifth enhancement device modifying said fifth pair of source signals to create ninth and tenth component signals representative of said fifth pair of source signals;

a sixth enhancement device receiving a sixth pair of said audio source signals, said sixth enhancement device modifying said sixth pair of source signals to create eleventh and twelfth component signals representative of said sixth pair of source signals; and

wherein;

said first output signal represents a composite of said first component signal, said third component signal, and said eleventh component signal;

said second output signal represents a composite of said second component signal, said fifth component signal, and said tenth component signal;

said third output signal represents a composite of said fourth component signal, said seventh component signal, and said ninth component signal; and

said fourth output signal represents a composite of said sixth component signal, said eighth component signal, and said twelfth component signal.

27. The audio enhancement system of claim 22 wherein said first, second, third, and fourth enhancement devices modify said corresponding pairs of source signals by selectively emphasizing the ambient information within said corresponding pairs of source signals.

28. The audio enhancement system of claim 22 wherein said audio enhancement system if formed upon a semiconductor substrate.

29. The audio enhancement system of claim 22 wherein said audio enhancement system is implemented by a digital signal processor.

30. The audio enhancement system of claim 22 wherein each of said output signals is amplified and directed to a plurality of speakers situated around a listener within the surround sound environment.

31. A method of enhancing sound in a surround sound reproduction environment wherein the surround sound environment has at least four separate audio source signals designated for speakers situated within the reproduction environment and placed around a listener, the method of enhancing comprising the following steps:

providing four audio source signals generated from a stereo signal decoder during playback of a recorded audio signal; and

modifying different combinations of said four audio source signals to create four enhanced audio signals wherein each of said four enhanced audio signals is modified as a function of at least three of said audio source signals, said enhanced audio signals creating an immersive sound experience for the listener when the enhanced audio signals are played through speakers of a reproduction environment.

32. The method of claim 31 further comprising the additional step of amplifying said enhanced audio signals to allow for reproduction by speakers within the surround sound reproduction environment.

33. The method of claim 31 wherein each of said audio source signals is modified as a function of said at least two additional source signals to create two component signals, and wherein said component signals which correspond to a common audio source signal are combined to form said enhanced audio signals.

34. A method of enhancing a group of audio source signals generated for playback in a surround sound environment wherein the audio source signals are designated for speakers placed around a listener, the audio source signals comprising a left-front signal (L_f), a right-front signal (R_f), a left-rear signal (L_r), and a right-rear signal (R_r), the method of enhancing comprising the following steps:

generating first and second component signals from the source signals L_f and R_f wherein the first and second component signals are modified as a function of the source signals L_f and R_f, the first component signal corresponding to the signal L_f and the second component signal corresponding to the signal R_f ;

generating third and fourth component signals from the source signals L_f, and L_r wherein the third and fourth component signals are modified as a function of the source signals L_f and L_R, the third component signal corresponding to the signal L_f and the fourth component signal corresponding to the signal L_r ;

generating fifth and sixth component signals from the source signals R_f and R_r wherein the fifth and sixth component signals are modified as a function of the source signals R_f and R_r, the fifth component signal corresponding to the signal R_f and the sixth component signal corresponding to the signal R_r ;

generating seventh and eighth component signals from the source signals L_r and R_r wherein the seventh and eighth component signals are modified as a function of the source signals L_r and R_r, the seventh component signal corresponding to the signal L_r and the eighth component signal corresponding to the signal R_r ;

combining the first and third component signals to generate a composite and enhanced left-front output signal, L_f(enhanced), for reproduction in said surround sound environment;

combining the second and fifth component signals to generate a composite and enhanced right-front output signal, R_f(enhanced), for reproduction in said surround sound environment;

combining the fourth and seventh component signals to generate a composite and enhanced left-rear output signal, L_r(enhanced), for reproduction in said surround sound environment; and

combining the sixth and eighth component signals to generate a composite and enhanced right-rear output signal, R_r(enhanced), for reproduction in said surround sound environment.

35. The method of enhancing a group of audio source signals as recited in claim 34 wherein each of said eight component signals contains ambient signal information which has been equalized, relative to ambient information in said corresponding source signal, to obtain a broader perceived sound stage with respect to any two of said enhanced output signals.

36. A method of enhancing a group of audio source signals generated for playback in a surround sound environment wherein the audio source signals are designated for speakers placed around a listener, the audio source signals comprising a left-front signal (L_f), a right-front signal (R_f), a left-rear signal (L_r), and a right-rear signal (R_r), said method of enhancing comprising modifying said audio source signals to create four corresponding enhanced audio signals wherein each of the four enhanced audio signals is modified as a function of its corresponding audio source signal and at least two additional audio source signals in accordance with the following equations:

space="preserve" listing-type="equation">L.sub.f(enhanced) =K.sub.1 (M.sub.1 (L.sub.f, R.sub.f)+M.sub.2 (L.sub.f, L.sub.r)),

space="preserve" listing-type="equation">R.sub.f(enhanced) =K.sub.2 (M.sub.3 (L.sub.f, R.sub.f)+M.sub.4 (R.sub.f, R.sub.r)),

space="preserve" listing-type="equation">L.sub.r(enhanced) =K.sub.3 (M.sub.5 (L.sub.f, L.sub.r)+M.sub.6 (L.sub.r, R.sub.r)),

and

space="preserve" listing-type="equation">R.sub.r(enhanced) =K.sub.4 (M.sub.7 (R.sub.f, R.sub.r)+M.sub.8 (L.sub.r, R.sub.r)),

where M₁ -M₈ are independent variables which dictate the level and type of modification to the audio source signals, and K₁ -K₄ are independent variables which determine the gain of the enhanced audio signals.

37. The method of enhancing a group of audio source signals as recited in claim 36 wherein the independent variables M₁ -M₈ represent equalization of ambient audio information present in the corresponding audio source signals.