Apparatus for expanding and controlling sound fields

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.

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.

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.

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.