Sound enhancement system

• US 6,281,749 B1
• Filed: 06/17/1997
• Issued: 08/28/2001
• Est. Priority Date: 06/17/1997
• Status: Expired due to Term

• Current Assignee: DTS, Inc. (Adeia Inc.)
• Original Assignee: SRS Labs Incorporated (Adeia Inc.)
• Inventors: Kraemer, Alan D., Klayman, Arnold I.
• Primary Examiner(s): Isen, Forester W.
• Assistant Examiner(s): PENDLETON, BRIAN T
• Application Number:
  US08/877,439
• Time in Patent Office: 1,533 Days
• Field of Search: 381/99, 381/98, 381/1, 381/28, 330/252, 330/258, 330/69, 375/318, 327/246
• US Class Current: 330/252
• CPC Class Codes: H03F 2203/45458 the CSC comprising one or more capacitors
• CPC Class Codes: H03F 2203/45544 the IC comprising one or more capacitors, e.g. coupling capacitors
• CPC Class Codes: H03F 2203/45594 the IC comprising one or more resistors, which are not biasing resistor
• CPC Class Codes: H03F 2203/45631 the LC comprising one or more capacitors, e.g. coupling capacitors
• CPC Class Codes: H03F 2203/45702 the LC comprising two resistors
• CPC Class Codes: H03F 3/45098 PI types H03F3/45125, H03F3/45152 take precedence

Abstract

The present invention provides an audio enhancement apparatus and method which spectrally shapes the differential information in a pair of audio signals so as to create an immersive, three-dimensional effect when the audio signals are acoustically reproduced. In a preferred embodiment, the invention includes a two-transistor amplifier which spectrally shapes the differential information with what are called cross-over networks. The cross-over networks spectrally shape the differential information by selectively emphasizing or de-emphasizing certain frequencies in the differential information. In addition, the preferred embodiment adjusts the level of the sound which is common to both input signals to reduce clipping.

Claims

1. An audio enhancement system comprising:

at least two audio signals, said audio signals having common-mode information which is common to said audio signals and differential information which is not common to said audio signals;

a first transistor in communication with one of said audio signals, said first transistor having a first collector and a first emitter;

a second transistor in communication with one of said audio signals, said second transistor having a second collector and a second emitter;

a first filter in communication with said first emitter and said second emitter, said first filter configured to modify a first set of frequencies in said differential information to create a first set of modified differential information;

a second filter in communication with said first emitter and said second emitter, said second filter configured to modify a second set of frequencies in said differential information to create a second set of modified differential information; and

a third filter in communication with said first collector and said second collector, said third filter configured to modify a third set of frequencies in said differential information to create a third set of modified differential information, wherein said first, second and third sets of modified differential information are combined with said common-mode information to create at least two enhanced output signals.

2. The audio enhancement system of claim 1 wherein said modified first set of frequencies de-emphasizes frequencies in a low frequency range relative to frequencies above said low frequency range.

3. The audio enhancement system of claim 1 wherein said modified second set of frequencies de-emphasizes frequencies below a high frequency range relative to frequencies in said high frequency range.

4. The audio enhancement system of claim 1 wherein said modified third set of frequencies de-emphasizes frequencies below a mid frequency range relative to frequencies in said mid frequency range.

5. The audio enhancement system of claim 1 wherein said first, second and third set of modified frequencies in said differential information are combined to create a corrected differential curve.

6. The audio enhancement system of claim 5 wherein said corrected differential curve de-emphasizes frequencies below approximately 125 hertz relative to frequencies near approximately 125 hertz.

7. The audio enhancement system of claim 5 wherein said corrected differential curve de-emphasizes frequencies between approximately 125 hertz and approximately 1.8 kilohertz relative to frequencies near approximately 125 hertz.

8. The audio enhancement system of claim 5 wherein said corrected differential curve emphasizes frequencies above approximately 1.8 kilohertz relative to frequencies near approximately 1.8 kilohertz.

9. An audio enhancement system comprising:

an audio generator configured to output at least two audio signals;

a pair of circuits coupled to said audio generator, said pair of circuits are configured to distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

a first cross-over network in communication with said pair of circuits, said first cross-over network configured to emphasize a first set of frequencies in said differential information relative to a second set of frequencies in said differential information, wherein said pair of circuits are further configured to alter said common-mode information in a different manner than said differential information, and wherein a portion of the frequencies in said common-mode information is adjusted by a desired number of decibels.

10. The audio enhancement system of claim 9 wherein said pair of circuits are a pair of amplifiers.

11. The audio enhancement system of claim 9 wherein said pair of circuits are a pair of transistors.

12. The audio enhancement system of claim 9 wherein said first cross-over network comprises at least one resistor and one capacitor.

13. The audio enhancement system of claim 9 wherein said pair of circuits output a combination of said common-mode information and said modified differential information as a pair of output signals.

14. The audio enhancement system of claim 13 further comprising at least two output buffers coupled to said pair of circuits, said output buffers configured to buffer said output signals from said pair of circuits.

15. The audio enhancement system of claim 14 further comprising at least two speakers coupled to said output signals, said speakers configured to reproduce an enhanced sound image.

16. An audio enhancement system comprising:

an audio generator configured to output at least two audio signals;

a pair of circuits coupled to said audio generator, said pair of circuits are configured to distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

a first cross-over network in communication with said pair of circuits, said first cross-over network configured to emphasize a first set of frequencies in said differential information relative to a second set of frequencies in said differential information and a second cross-over network in communication with said pair of circuits, said second cross-over network configured to modify a second set of frequencies in said differential information in a different manner than said first set of frequencies modified by said first cross-over network, wherein said first and second set of modified frequencies in said differential information create a corrected differential curve wherein frequencies below a mid range of frequencies are de-emphasized relative to frequencies in said mid range of frequencies.

17. The audio enhancement system of claim 16 wherein said pair of circuits are further configured to alter said common-mode information in a different manner than said differential information.

18. An audio enhancement system comprising:

an audio generator configured to output at least two audio signals;

a pair of circuits coupled to said audio generator, said pair of circuits are configured to distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

a first cross-over network in communication with said pair of circuits, said first cross-over network configured to emphasize a first set of frequencies in said differential information relative to a second set of frequencies in said differential information and a second cross-over network in communication with said pair of circuits, said second cross-over network configured to modify a second set of frequencies in said differential information in a different manner than said first set of frequencies modified by said first cross-over network, wherein said first and second set of modified frequencies in said differential information create a corrected differential curve wherein frequencies above a mid range of frequencies are de-emphasized relative to frequencies in said mid range of frequencies.

19. An audio enhancement system comprising:

an audio generator configured to output at least two audio signals;

a pair of circuits coupled to said audio generator, said pair of circuits are configured to distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

a first cross-over network in communication with said pair of circuits, said first cross-over network configured to emphasize a first set of frequencies in said differential information relative to a second set of frequencies in said differential information and a second cross-over network in communication with said pair of circuits, said second cross-over network configured to modify a second set of frequencies in said differential information in a different manner than said first set of frequencies modified by said first cross-over network, wherein said first and second set of modified frequencies in said differential information create a corrected differential curve wherein frequencies below approximately 5 kilohertz are de-emphasized relative to frequencies at approximately 5 kilohertz.

20. An audio enhancement system comprising:

an audio generator configured to output at least two audio signals;

a pair of circuits coupled to said audio generator, said pair of circuits are configured to distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

a first cross-over network in communication with said pair of circuits, said first cross-over network configured to emphasize a first set of frequencies in said differential information relative to a second set of frequencies in said differential information and a second cross-over network in communication with said pair of circuits, said second cross-over network configured to modify a second set of frequencies in said differential information in a different manner than said first set of frequencies modified by said first cross-over network, wherein said first and second set of modified frequencies in said differential information are combined to create a corrected differential curve wherein frequencies above approximately 5 kilohertz are de-emphasized relative to frequencies at approximately 5 kilohertz.

21. A method of enhancing audio information comprising the steps of:

directing at least two audio signals to a pair of transistors which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said transistors wherein said step of spectrally shaping creates a corrected differential curve wherein a low range of frequencies are de-emphasized relative to frequencies above said low range of frequencies.

22. The method of claim 21 further comprising the step of variably adjusting said spectral shaping.

23. The method of claim 21 further comprising the step of modifying said common-mode information.

24. The method of claim 23 wherein said step of modifying said common-mode information modifies said common-mode information in a different manner than said differential information.

25. The method of claim 23 further comprising the step of variably modifying said common-mode information.

26. The method of claim 21 further comprising the step of combining said spectrally shaped differential information and said common-mode information to create at least two output signals.

27. The method of claim 26 further comprising the steps of coupling said output signals to at least two speakers.

28. The method of claim 26 further comprising the steps of coupling said output signals to an audio processing device.

29. A method of enhancing audio information comprising the steps of:

directing at least two audio signals to a pair of transistors which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said transistors, wherein said step of spectrally shaping creates a corrected differential curve wherein frequencies below approximately 125 hertz are de-emphasized relative to frequencies near 125 hertz.

30. A method of enhancing audio information comprising the steps of:

directing at least two audio signals to a pair of transistors which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said transistors, wherein said step of spectrally shaping creates a corrected differential curve wherein a mid range of frequencies are de-emphasized relative to frequencies at the beginning of said mid range of frequencies.

31. A method of enhancing audio information comprising the steps of:

directing at least two audio signals to a pair of transistors which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said transistors, wherein said step of spectrally shaping creates a corrected differential curve wherein frequencies between approximately 125 hertz and approximately 1.8 kilohertz are de-emphasized relative to frequencies near 125 hertz.

32. A method of enhancing audio information comprising the steps of:

directing at least two audio signals to a pair of transistors which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said transistors wherein said step of spectrally shaping creates a corrected differential curve wherein frequencies above approximately 1.8 kilohertz are emphasized relative to frequencies near 1.8 kilohertz.

33. An audio enhancement system comprising:

a pair of circuits that receive at least a pair of audio signals, said pair of circuits are configured to distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

a first cross-over network in communication with said pair of circuits, said first cross-over network configured to emphasize a first set of frequencies in said differential information relative to a second set of frequencies in said differential information and a second cross-over network in communication with said pair of circuits, said second cross-over network configured to modify a second set of frequencies in said differential information in a different manner than said first set of frequencies modified by said first cross-over network.

34. The audio enhancement system of claim 33 wherein said pair of circuits are a pair of amplifiers.

35. The audio enhancement system of claim 33 wherein said pair of circuits are a pair of transistors.

36. The audio enhancement system of claim 33 wherein said first cross-over network comprises at least one resistor and one capacitor.

37. The audio enhancement system of claim 33 wherein said pair of circuits output a combination of said common-mode information and said modified differential information as a pair of output signals.

38. The audio enhancement system of claim 33 further comprising at least two output buffers coupled to said pair of circuits, said output buffers configured to buffer said output signals from said pair of circuits.

39. The audio enhancement system of claim 33 further comprising at least two speakers coupled to said output signals, said speakers configured to reproduce an enhanced sound image.

40. The audio enhancement system of claim 33 wherein said first and second set of modified frequencies in said differential information create a corrected differential curve wherein frequencies below a mid range of frequencies are de-emphasized relative to frequencies in said mid range of frequencies.

41. The audio enhancement system of claim 33 wherein said first and second set of modified frequencies in said differential information create a corrected differential curve wherein frequencies above a mid range of frequencies are de-emphasized relative to frequencies in said mid range of frequencies.

42. The audio enhancement system of claim 33 wherein said first and second set of modified frequencies in said differential information create a corrected differential curve wherein frequencies below approximately 5 kilohertz are de-emphasized relative to frequencies at approximately 5 kilohertz.

55. The audio enhancement system of claim 33 wherein said first and second set of modified frequencies in said differential information are combined to create a corrected differential curve wherein frequencies above approximately 5 kilohertz are de-emphasized relative to frequencies at approximately 5 kilohertz.

56. The audio enhancement system of claim 33 wherein said pair of circuits are further configured to alter said common-mode information in a different manner than said differential information.

57. The audio enhancement system of claim 56 wherein a portion of the frequencies in said common-mode information is adjusted by a desired number of decibels.

43. A method of enhancing audio information comprising the steps of:

receiving at least two audio signals with a pair of circuits which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said pair of circuits, wherein said step of spectrally shaping creates a corrected differential curve wherein a low range of frequencies are de-emphasized relative to frequencies above said low range of frequencies.

44. The method of claim 43 further comprising the step of variably adjusting said spectral shaping.

45. The method of claim 43 further comprising the step of modifying said common-mode information.

46. The method of claim 45 wherein said step of modifying said common-mode information modifies said common-mode information in a different manner than said differential information.

47. The method of claim 45 further comprising the step of variably modifying said common-mode information.

48. The method of claim 43 further comprising the step of combining said spectrally shaped differential information and said common-mode information to create at least two output signals.

49. The method of claim 48 further comprising the steps of coupling said output signals to at least two speakers.

50. The method of claim 48 further comprising the steps of coupling said output signals to an audio processing device.

51. A method of enhancing audio information comprising the steps of:

receiving at least two audio signals with a pair of circuits which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said pair of circuits, wherein said step of spectrally shaping creates a corrected differential curve wherein frequencies below approximately 125 hertz are de-emphasized relative to frequencies near 125 hertz.

52. A method of enhancing audio information comprising the steps of:

receiving at least two audio signals with a pair of circuits which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said pair of circuits, wherein said step of spectrally shaping creates a corrected differential curve wherein a mid range of frequencies are de-emphasized relative to frequencies at the beginning of said mid range of frequencies.

53. A method of enhancing audio information comprising the steps of:

receiving at least two audio signals with a pair of circuits which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said pair of circuits, wherein said step of spectrally shaping creates a corrected differential curve wherein frequencies between approximately 125 hertz and approximately 1.8 kilohertz are de-emphasized relative to frequencies near 125 hertz.

54. A method of enhancing audio information comprising the steps of:

receiving at least two audio signals with a pair of circuits which distinguish common-mode information which is common to said audio signals from differential information which is not common to said audio signals; and

spectrally shaping said differential information with multiple cross-over networks which are in communication with said pair of circuits, wherein said step of spectrally shaping creates a corrected differential curve wherein frequencies above approximately 1.8 kilohertz are emphasized relative to frequencies near 1.8 kilohertz.