Apparatus for expanding and controlling sound fields

• US 5,710,818 A
• Filed: 01/31/1994
• Issued: 01/20/1998
• Est. Priority Date: 11/01/1990
• Status: Expired due to Fees

• Current Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Inventors: Yamaguchi, Hiroyuki, Sako, Kazuya, Yamato, Toshitaka, Kowaki, Hiroshi
• Primary Examiner(s): Isen, Forester W.
• Application Number:
  US08/188,738
• Time in Patent Office: 1,450 Days
• Field of Search: 381/1, 381/63, 381/86
• US Class Current: 381/1
• CPC Class Codes: H04S 1/007 in which the audio signals are in digital form data reduction aspects thereof based on psychoacoustics G10L19/02

Abstract

As in a compartment of an automotive vehicle, when a left- and a right-channel loudspeakers are disposed at angularly different positions from each other with respect to a frontward direction of a listening position, there will be formed a sound field laterally asymmetric with respect to the frontward direction of the listening position. In order to correct the asymmetry of the sound field, a crosstalk signal obtained by correcting the phase and the level of an acoustic signal of the left-channel from an acoustic signal source and a crosstalk adjustment signal obtained by correcting the level of the acoustic signal of the left-channel are fed to the right loudspeaker, or a center loudspeaker disposed between the left and right loudspeakers, together with an acoustic signal of the right-channel from the acoustic signal source. Similarly, a crosstalk signal obtained by correcting the phase and the level of an acoustic signal of the right-channel and a crosstalk adjustment signal obtained by correcting the level of the acoustic signal of the right-channel are fed to the left or center loudspeaker together with the acoustic signal of the left-channel from the acoustic signal source.

Claims

1. An apparatus for expanding a stereophonic sound field produced by at least two loudspeakers disposed asymmetrically in front of a listener, said apparatus comprising:

a right and a left sound input signal;

a plurality of first circuits including phase shifting means and attenuating means;

a filter for filtering signals of different frequency bands interposed before the plurality of said first circuits

a second circuit including variable level adjusting means; and

,

a delay circuit for delaying the right and left sound input signals to obtain respective delayed right and left sound input signals, respectively;

wherein said first circuits produce a right and a left crosstalk signal from the right and left sound input signals by phase shifting using the phase shifting means and by level correction using the attenuating means, and expand and symmetrize the sound field with respect to the listener by admixing the right and left crosstalk signals to the delayed left and right sound input signals, respectively,

wherein the frequency range of the right and left input signals is subdivided into plural partial bands so as to obtain the crosstalk signals, and

wherein said second circuit produces a right and a left crosstalk adjustment signal from the right and left sound input signals by level adjustment using the variable level adjusting means, and facilitates the adjustment of sound field expansion for the listener by admixing the right and left crosstalk adjustment signals to the delayed left and right sound input signals, respectively.

2. An apparatus for expanding a stereophonic sound field produced by at least two loudspeakers disposed asymmetrically in front of a listener, said apparatus comprising:

a right and a left sound input signal;

a first circuit including phase shifting means and attenuating means;

a second circuit including variable level adjusting means;

a filter for filtering signals of the frequency band of a medium sound range located before the second circuit; and

a delay circuit for delaying the right and left sound input signals to obtain respective delayed right and left sound input signals, respectively;

wherein said first circuit produces a right and a left crosstalk signal from the right and left sound input signals by phase shifting using the phase shifting means and by level correction using the attenuating means, and expands and symmetrizes the sound field with respect to the listener by a mixing the right and left crosstalk signals to the delayed left and right sound input signals, respectively,

wherein said second circuit produces a right and a left crosstalk adjustment signal from the right and left sound input signals by level adjustment using the variable level adjusting means, and facilitates the adjustment of sound field expansion for the listener by admixing the right and left crosstalk adjustment signals to the delayed left and right sound input signals, respectively, and

wherein a band width of the crosstalk adjustment signals is limited to the frequency band of the medium sound range.

3. An apparatus for expanding a stereophonic sound field produced by at least two loudspeakers disposed asymmetrically in front of a listener, said apparatus comprising:

a right and a left sound input signal;

a first circuit including phase shifting means and attenuating means;

a second circuit including variable level adjusting means; and

a third circuit including delay means and coefficient means, wherein said third circuit produces a right and a left reflected sound signal from the right and left sound input signals, respectively, by delay using the delay means and level correction using the coefficient means,

wherein said first circuit produces at least one of a) a first set of right and a left crosstalk signal from the right and left sound input signals by phase shifting using the phase shifting means and by level correction using the attenuating means, and b) a second set of right and left crosstalk signals from the right and left reflected sound signals by phase shifting using the phase shifting means and by level correcting using the attenuating means, and expands and symmetrizes the sound field with respect to the listener by admixing at least one of c) the first set of right and left crosstalk signals to the left and right sound input signals, respectively, and d) by admixing the second set of right and left crosstalk signals to the left and right reflected sound signals, respectively, and

wherein said second circuit produces at least one of e) a first set of right and a left crosstalk adjustment signals from the right and left sound input signals by level adjustment using the variable level adjusting means, and f) a second set of right and left crosstalk adjustment signals from the right and left reflected sound signals by level adjustment using the variable level adjusting means, and facilitates the adjustment of sound field expansion for the listener by admixing at least one of g) the first set of right and left crosstalk adjustment signals to the left and right sound input signals, respectively, and h) the second set of right and left crosstalk adjustment signals to the left and right reflected sound signals, respectively.

4. An apparatus as claimed in claim 3, comprising a plurality of said first circuits, and a filter for filtering signals of different frequency bands interposed before the plurality of said first circuits, wherein the frequency range is subdivided into plural partial bands so as to obtain the crosstalk signals.

5. An apparatus as claimed in claim 3, further comprising a filter for filtering signals of the frequency band of a medium sound range located before the second circuit, wherein the band width of the crosstalk adjustment signals is limited to the frequency band of the medium sound range.

12. An apparatus as claimed in claim 3, wherein said first circuit comprises a fourth circuit and a fifth circuit;

the fourth circuit produces the first set of right and left crosstalk signals from the right and left sound input signals, and expands and symmetrizes the sound field with respect to the listener by admixing the first set of right and left crosstalk signals to the left and right sound input signals, respectively; and

the fifth circuit produces the second set of right and left crosstalk signals from the right and left reflected sound signals, and expands and symmetrizes the sound field with respect to the listener by admixing the second set of right and left crosstalk signals to the left and right reflected sound signals, respectively.

13. An apparatus as claimed in claim 3, wherein said second circuit comprises a fourth circuit and a fifth circuit;

the fourth circuit produces the first set of right and left crosstalk adjustment signals from the right and left sound input signals, and facilitates the adjustment of sound field expansion for the listener by admixing the first set of right and left crosstalk adjustment signals to the left and right sound input signals, respectively; and

the fifth circuit produces the second set of right and left crosstalk adjustment signals from the right and left reflected sound signals, and facilitates the adjustment of sound field expansion for the listener by admixing the second set of right and left crosstalk adjustment signals to the left and right reflected sound signals, respectively.

6. An apparatus for expanding a stereophonic sound field produced by three loudspeakers disposed asymmetrically in front of a listener, said apparatus comprising:

a right and a left sound input signal;

a first circuit including phase shifting means and attenuating means; and

a second circuit including variable level adjusting means,

wherein said first circuit produces a right and a left crosstalk signal from the right and left sound input signals by phase shifting using the phase shifting means and by level correction using the attenuating means, and expands and symmetrizes the sound field with respect to the listener by admixing the right and left crosstalk signals to a central acoustic signal to which the right and left sound input signals have been added, and

wherein said second circuit produces a right and a left crosstalk adjustment signal from the right and left sound input signals by level adjustment using the variable level adjusting means, and facilitates the adjustment of sound field expansion for the listener by admixing the right and left crosstalk adjustment signals to the central acoustic signals.

7. An apparatus as claimed in claim 6, comprising a plurality of said first circuits, and a filter for filtering signals of different frequency bands interposed before the plurality of said first circuits, wherein the frequency range is subdivided into plural partial bands so as to obtain the crosstalk signals.

8. An apparatus as claimed in claim 6, further comprising a filter for filtering signals of the frequency band of a medium sound range located before the second circuit, wherein the band width of the crosstalk adjustment signals is limited to the frequency band of the medium sound range.

9. An apparatus for expanding a stereophonic sound field produced by three loudspeakers disposed asymmetrically in front of a listener, said apparatus comprising:

a right and a left sound input signal;

a first circuit including phase shifting means and attenuating means; and

a second circuit including variable level adjusting means,

a third circuit including delay means and coefficient means,

wherein said third circuit produces a right and a left reflected sound signal from the right and left sound input signals, respectively, by delay using the delay means and level correction using the coefficient means,

wherein said first circuit produces at least either of a right and a left crosstalk signal from the right and left sound input signals, respectively, by phase shifting using the phase shifting means and by level correction using the attenuating means, or a right and a left second crosstalk signal from the right and left reflected sound signals, respectively, and expands and symmetrizes the sound field with respect to the listener by admixing at least one of the first and second crosstalk signals to a central sound signal to which the right and left sound input signals have been added, or to a central reflected sound signal to which the right and left reflected sound signals have been added, and

wherein said second circuit produces at least either of the right and left crosstalk signals from the right and left sound input signals, respectively, by phase shifting using the phase shifting means and by level correction using the attenuating means, or the right and left second crosstalk signals from the right and left reflected sound signals, respectively, by level adjustment using the variable level adjusting means, and facilitates the adjustment of sound field expansion for the listener by admixing at least one of the right and left crosstalk adjustment signals and the right and left second crosstalk adjustment signals to the central sound signal or the central reflected sound signal.

10. An apparatus as claimed in claim 9, comprising a plurality of said first circuits, and a filter for filtering signals of different frequency bands interposed before the plurality of said first circuits, wherein the frequency range is subdivided into plural partial bands so as to obtain the crosstalk signals.

11. An apparatus as claimed in claim 9, further comprising a filter for filtering signals of the frequency band of a medium sound range located before the second circuit, wherein the band width of the crosstalk adjustment signals is limited to the frequency band of the medium sound range.