Portable audio playback device with bass enhancement

• US 20040014426A1
• Filed: 07/19/2002
• Published: 01/22/2004
• Est. Priority Date: 07/19/2002
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Ericsson Mobile Communications AB (Sony Group Corp.)
• Inventors: Moore, Richard A.
• Granted Patent: US 7,295,809 B2
• Time in Patent Office: Days
• US Class Current: 455/70
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones
• CPC Class Codes: H04R 3/14 Cross-over networks
• CPC Class Codes: H04R 5/04 Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments combinations of amplifiers H03F3/68; stereophonic systems H04S
• CPC Class Codes: H04S 2400/07 Generation or adaptation of the Low Frequency Effect [LFE] channel, e.g. distribution or signal processing

Abstract

Wirelessly linking a portable audio device to an external audio system permits the external audio system to generate audible signals that enhance local playback of audio by the portable device. For example, the portable device wirelessly transmits lower frequency components of an audio signal to a subwoofer system for reproduction of bass frequencies extending below the playback capability of the portable device. In this manner, the external audio system provides bass enhancement for the portable audio device. Wireless transmissions between the portable audio device and the external audio system may be, but are not limited to, optical or radio frequency (RF) transmissions. Where RF signaling is used, the wireless link may be based on wireless network links, such as those supported by Bluetooth and 802.11b standards, or based on, for example, dedicated RF interfaces.

Claims

1. A portable audio device comprising:

a portable audio playback unit comprising an audio circuit for generating an audio signal and at least one speaker coupled to the audio circuit, said speaker being responsive to the audio signal to generate a first audible signal; and

a wireless interface coupled to the audio circuit to transmit an enhancement signal derived from the audio signal to an external audio system that generates a second audible signal enhancing the first audible signal.

2. The portable audio device of claim 1 wherein the audio circuit comprises at least one delay matching element to match the delays of the first and second audible signals so that the first and second audible signals are time aligned.

3. The portable audio device of claim 2 wherein the delay matching element delays the first audible signal to match link delays associated with transmission of the enhancement signal to the external audio system.

4. The portable audio device of claim 2 wherein the delay matching element delays the first audible signal to match audible signal delays associated with output of the second audible signal from the audio system.

5. The portable audio system of claim 3 wherein the delay of the first audible signal is persistent so that transmission of the enhancement signal for enhancement of the first audible signal can be selectively enabled and disabled without creating an audible discontinuity.

6. The portable audio device of claim 1 wherein the audio circuit includes a first filter to generate the enhancement signal by filtering the audio signal.

7. The portable audio device of claim 6 wherein the first filter is a low-pass filter and the enhancement signal comprises low frequency components of the audio signal.

8. The portable device of claim 6 wherein the audio circuit further comprises a second filter to filter the audio signal to generate the first audible signal.

9. The portable audio device of claim 8 wherein the first and second filters form a cross-over filter.

10. The portable audio device of claim 8 wherein the first filter is a low pass filter and wherein the second filter is a high pass filter.

11. The portable audio device of claim 1 wherein the audio signal is multi-channel audio signal and wherein the audio playback unit includes at least two speakers, each outputting a respective channel of the multi-channel audio signal.

12. The portable audio device of claim 11 wherein the audio circuit further comprises a summer to generate the enhancement signal by combining two or more channels of the audio signal.

13. The portable audio device of claim 1 wherein the audio playback unit further comprises a control unit controlling the audio playback unit.

14. The portable audio device of claim 13 wherein the control unit sends control signals via the wireless interface to the external audio system to control the external audio system.

15. The portable audio device of claim 13 wherein the control unit sends volume control signals to the external audio system to control the volume of the second audible signal.

16. The portable audio device of claim 1 wherein the wireless interface comprises a digital wireless networking interface supporting communication via a digital wireless network link.

17. The portable audio device of claim 16 wherein the digital wireless network link includes a low data rate channel and wherein the enhancement signal is transmitted by said portable audio device to said external audio system over the low data rate channel.

18. The portable audio device of claim 17 wherein the low data rate channel is an unsupervised channel.

19. The portable audio device of claim 17 wherein the wireless networking interface is a Bluetooth interface and wherein the low data rate audio channel is a CVSD voice channel.

20. The portable audio device of claim 17 wherein the low data rate channel is time-shared by said audio playback unit with a telephony application for making voice calls.

21. The portable audio device of claim 20 including a playback mode during which the enhancement signal is transmitted over the low data rate channel to the external audio system, and a voice mode during which transmission of the enhancement signal is suspended and the low data rate channel is used to support a voice call.

22. The portable audio device of claim 17 wherein the wireless network link further includes a high data rate channel.

23. The portable audio device of claim 22 wherein the audio signal is derived from information received over the wireless interface on said high data rate channel.

24. The portable audio device of claim 1 wherein said wireless interface supports ad hoc networking so that said portable audio device detects availability of the external audio system for playback enhancement.

25. The portable audio device of claim 24 wherein said portable audio device automatically transmits the enhancement signal when the external audio system is available for play back enhancement.

26. The portable audio device of claim 24 wherein said portable audio device notifies a user of the portable audio device when the external audio system is available for playback enhancement.

27. An audio system comprising:

a portable audio device including a first audio circuit and at least one speaker to output a first audible signal responsive to an audio signal;

an external audio system including a second audio circuit and a woofer to enhance the first audible signal by producing a second audible signal responsive to low-frequency components of the audio signal; and

a wireless link to transmit the low-frequency components of the audio signal from the portable audio device to the external audio system.

28. The audio system of claim 27 wherein the first audio circuit comprises at least one delay matching element to match delays of the first and second audible signals so that the first and second audible signals are time aligned.

29. The audio system of claim 28 wherein the at least one delay matching element delays the first audible signal to match link delays associated with the transmission of the low-frequency components of the audio signal to the external audio system.

30. The portable audio system of claim 29 wherein the delay of the first audible signal is persistent so that transmission of the low-frequency components of the audio signal can be selectively enabled and disabled without creating an audible discontinuity.

31. The audio system of claim 27 wherein the first audio circuit includes a first filter for filtering the first audio signal to obtain the low-frequency components of the audio signal.

32. The audio system of claim 31 wherein the first filter is a low-pass filter to output an enhancement signal including the low-frequency components of the audio signal.

33. The portable device of claim 31 wherein the first audio circuit further comprises a second filter to filter the audio signal to generate the first audible signal.

34. The audio system of claim 33 wherein the first and second filters form a cross-over filter.

35. The audio system of claim 33 wherein the first filter is a low pass filter and wherein the second filter is a high pass filter.

36. The audio system of claim 27 wherein the audio signal is multi-channel audio signal and wherein the portable audio device includes at least two speakers, each outputting a respective channel of the multi-channel audio signal.

37. The audio system of claim 36 wherein the first audio circuit further comprises a summer to obtain the low-frequency components of the multi-channel audio signal by combining two or more channels of the multi-channel audio signal.

38. The audio system of claim 27 wherein the portable audio device further comprises a control unit controlling the audio playback unit.

39. The audio system of claim 38 wherein the control unit sends control signals via the wireless interface to the external audio system to control the external audio system.

40. The audio system of claim 38 wherein the control unit sends volume control signals to the external audio system to control the volume of the second audible signal.

41. The audio system of claim 27 wherein the wireless interface comprises a digital wireless networking interface supporting communication via a digital wireless network link.

42. The audio system of claim 41 wherein the digital wireless network link includes a low data rate channel and wherein the low-frequency components of the audio signal are transmitted as an enhancement signal by the portable audio device to the external audio system over the low data rate channel.

43. The audio system of claim 42 wherein the low data rate channel is an unsupervised channel.

44. The audio system of claim 42 wherein the wireless networking interface is a Bluetooth interface and wherein the low data rate channel is a CVSD voice channel.

45. The audio system of claim 42 wherein the portable audio device time-shares the low data rate channel with a telephony application for making voice calls.

46. The audio system of claim 45 including a playback mode during which the enhancement signal is transmitted over the low data rate channel to the external audio system, and a voice mode during which transmission of the enhancement signal is suspended and the low data rate channel is used to support a voice call.

47. The audio system of claim 42 wherein the wireless network link further includes a high data rate channel.

48. The audio system of claim 47 wherein the audio signal is derived from information received over the wireless interface on the high data rate channel.

49. The audio system of claim 27 wherein the wireless interface supports ad hoc networking so that the portable audio device detects availability of the external audio system for playback enhancement.

50. The audio system of claim 49 wherein the portable audio device automatically transmits an enhancement signal comprising the low-frequency components of the audio signal when the external audio system is available for playback enhancement.

51. The audio system of claim 49 wherein the portable audio device notifies a user of the portable audio device when the external audio system is available for playback enhancement.

52. A method of enhancing audio playback of a portable audio device, the method comprising:

outputting a first audible signal from the portable audio device responsive to an audio signal; and

transmitting an enhancement signal containing the low-frequency components of the audio signal from the portable audio device to an external audio system that provides bass enhancement.

53. The method of claim 52, further comprising outputting a second audible signal from the external audio system responsive to the enhancement signal, wherein the second audible signal provides bass enhancement for the first audible signal.

54. The method of claim 52 further comprising matching delays of the first and second audible signals.

55. The method of claim 54 wherein matching delays of the first and second audible signals comprises delaying the first audible signal output from the portable audio device to match a link delay associated with the transmission of the enhancement signal to the external audio system.

56. The method of claim 55 further comprising delaying the first audible signal during periods when no enhancement signal is being transmitted.

57. The method of claim 52 further comprising filtering the audio signal in a first filter to generate the enhancement signal.

58. The method of claim 57 wherein the first filter is a low pass filer that removes high frequency components of the audio signal to generate the enhancement signal.

59. The method of claim 57 further comprising filtering the audio signal in a second filter to generate the first audible signal.

60. The method of claim 59 wherein the first and second filters form a cross-over filter.

61. The method of claim 60 wherein the first filter is a low pass filter and the second filter is a high pass filter.

62. The method of claim 52 wherein the audio signal is a multi-channel audio signal and wherein the first audible signal is generated by two or more speakers.

63. The method of claim 62 further comprising combining two or more channels of the multi-channel audio signal to generate the enhancement signal.

64. The method of claim 52 further comprising sending control signals from the portable audio device to the external audio system to control the operation of the external audio system.

65. The method of claim 64 wherein controlling operation of the external audio system comprises sending volume control signals from the portable audio device to the external audio system to control the volume of the second audible signal.

66. The method of claim 52 wherein transmitting an enhancement signal containing the low-frequency components of the audio signal from the portable audio device to an external audio system comprises transmitting the enhancement signal over a wireless network interface.

67. The method of claim 66 wherein the wireless network interface provides support for a digital wireless network link.

68. The method of claim 67 wherein the digital wireless network link includes a low data rate channel and wherein the audio enhancement signal is transmitted by the portable audio device to the external audio system over the low data rate channel.

69. The method of claim 68 wherein the low data rate channel is an unsupervised channel.

70. The method of claim 69 wherein the wireless network interface is a Bluetooth interface and wherein the low data rate audio channel is a CVSD voice channel.

71. The method of claim 68 wherein the low data rate channel is time-shared by the portable audio device with a telephony application for making voice calls.

72. The method of claim 71 further comprising suspending transmission of the enhancement signal during a voice call.

73. The method of claim 68 wherein the wireless network link further includes a high data rate channel.

74. The method of claim 73 further comprising receiving audio content over the high data rate channel, wherein the audio signal is derived from the audio content received over the high data rate channel.

75. The method of claim 52 further comprising detecting availability of the external audio system for playback enhancement.

76. The method of claim 75 further comprising automatically transmitting the enhancement signal when the external audio system is available for playback enhancement.

77. The method of claim 75 further comprising notifying a user of the portable audio device when the external audio system is available for playback enhancement.