Apparatus and method for enhancing the perceived sound image of a sound signal by source localization

Claim 1

An apparatus for enhancing the perceived sound image of a stereophonic, audio reproduction system whose inputs are a right and a left signal channels, and whose outputs are a modified right, a modified left and a centersignal channels, comprising: first and second input terminals to which the right and left signal channels are respectively applied; a first modified right, a first modified left and center output terminals; first band pass means connected to said first input terminal for attenuating signal frequencies ouside of a selected predetermined bandwidth; first phase correction means connected to the first band pass means for shifting the phase of the signal output from the first band pass means to maintain phase integrity with the left signal channel; first voltage control means connected to the first phase correction means for selectively controlling the amplitude of the signal output from the first phase correction means; first inverter means connected to the first control means for inverting the signal output from the first control means; first mixer means connected to the first inverter means and to the second input terminal and to the first modified left output terminal for applying a composite modified left signal channel formed by combining the signal output from the first inverter means and the left signal channel and applying the output signal to the first modified left output terminal; second band pass means connected to the second input terminal for attenuating signal frequencies outside of said selected predetermined bandwidth; second phase correction means connected to the second band pass means for shifting the phase of the signal output from the second band pass means to maintain phase integrity with the right signal channel; second control means connected to the second phase correction means for selectively controlling the amplitude of the signal output from the second phase correction means; second inverter means connected to the second control means for inverting the signal output from the second control means; second mixer means connected to the second inverter means and to the first input terminal and to the first modified right output terminal for applying a composite modified right signal channel formed by combining the signal output from the second inverter means and the right signal channel to the first modified right output terminal; center mixer means connected to the first and to the second input terminals for combining the right and left signal channels, respectively; high pass filter means connected to the center mixer means and to the center output terminal for attenuating the signal output of the center mixer means below a selected predetermined center cutoff frequency and applying the output signal to the center output terminal.

Claim 2

An apparatus for enhancing the perceived sound image of a stereophonic, audio reproduction system whose inputs are a right and a left signal channels, and whose outputs are a modified right, a modified left and a centersignal channels, comprising: first and second input terminals to which the right and left signal channels are respectively applied; a first modified right, a first modified left and center output terminals; first band pass means connected to said first input terminal for attenuating signal frequencies ouside of a selected predetermined bandwidth; first phase correction means connected to the first band pass means for shifting the phase of the signal output from the first band pass means to maintain phase integrity with the left signal channel; first voltage control means connected to the first phase correction means for selectively controlling the amplitude of the signal output from the first phase correction means; first inverter means connected to the first control means for inverting the signal output from the first control means; first mixer means connected to the first inverter means and to the second input terminal and to the first modified left output terminal for applying a composite modified left signal channel formed by combining the signal output from the first inverter means and the left signal channel and applying the output signal to the first modified left output terminal; second band pass means connected to the second input terminal for attenuating signal frequencies outside of said selected predetermined bandwidth; second phase correction means connected to the second band pass means for shifting the phase of the signal output from the second band pass means to maintain phase integrity with the right signal channel; second control means connected to the second phase correction means for selectively controlling the amplitude of the signal output from the second phase correction means; second inverter means connected to the second control means for inverting the signal output from the second control means; second mixer means connected to the second inverter means and to the first input terminal and to the first modified right output terminal for applying a composite modified right signal channel formed by combining the signal output from the second inverter means and the right signal channel to the first modified right output terminal; center mixer means connected to the first and to the second input terminals for combining the right and left signal channels, respectively; high pass filter means connected to the center mixer means and to the center output terminal for attenuating the signal output of the center mixer means below a selected predetermined center cutoff frequency and applying the output signal to the center output terminal.

Claim 13

A method for enhancing the perceived sound image of a stereophonic audio reproduction system whose inputs are derived from a two channel stereophonic source by processing said inputs into a modified right, a modified left, and a center signal channels, comprising: producing the modified left signal channel by attenuating those frequencies in the right signal channel that are outside of a selected predetermined bandwidth to produce a limited bandwidth right signal channel; correcting the phase angle of the limited bandwidth right signal channel; controlling the amplitude of the limited bandwidth right signal channel; inverting the limited bandwidth right signal channel; mixing the limited bandwidth, phase angle corrected, amplitude controlled, inverted right signal channel with the left signal channel to produce the modified left signal channel; outputting the modified left signal channel; producing the modified right signal channel by attenuating those frequencies in the left signal channel that are outside of said selected predetermined bandwidth to produce a limited bandwidth left signal channel; correcting the phase angle of the limited bandwidth left signal channel; controlling the amplitude of the limited bandwidth left signal channel; inverting the limited bandwidth left signal channel; mixing the limited bandwidth, phase angle corrected, amplitude controlled, inverted left signal channel with the right signal channel to produce the modified right signal channel; outputting the modified right signal channel; and, producing the center channel by mixing the right and the left signal channels to form a combined signal; attenuating those frequencies in the combined signal channel that are below a selected predetermined center high pass cutoff frequency to produce the center signal channel; and outputting the center signal channel.

Claim 14

A method for enhancing the perceived sound image of a stereophonic audio reproduction system whose inputs are derived from a two channel stereophonic source by processing said inputs into a modified right, a modified left, and a center signal channels, comprising: producing the modified left signal channel by attenuating those frequencies in the right signal channel that are outside of a selected predetermined bandwidth to produce a limited bandwidth right signal channel; correcting the phase angle of the limited bandwidth right signal channel; controlling the amplitude of the limited bandwidth right signal channel; inverting the limited bandwidth right signal channel; mixing the limited bandwidth, phase angle corrected, amplitude controlled, inverted right signal channel with the left signal channel to produce the modified left signal channel; outputting the modified left signal channel; producing the modified right signal channel by attenuating those frequencies in the left signal channel that are outside of said selected predetermined bandwidth to produce a limited bandwidth left signal channel; correcting the phase angle of the limited bandwidth left signal channel; controlling the amplitude of the limited bandwidth left signal channel; inverting the limited bandwidth left signal channel; mixing the limited bandwidth, phase angle corrected, amplitude controlled, inverted left signal channel with the right signal channel to produce the modified right signal channel; outputting the modified right signal channel; and, producing the center channel by mixing the right and the left signal channels to form a combined signal; attenuating those frequencies in the combined signal channel that are below a selected predetermined center high pass cutoff frequency to produce the center signal channel; and outputting the center signal channel.

Claim 17

An apparatus for enhancing the perceived sound image of a stereophonic, audio reproduction system having a right and a left channel signal inputs and a modified right, a modified left and a center signal channel outputs comprising: means for producing modified left and right signals where only audio information common to the right and left signal channel inputs is attenuated within a specified predetermined bandwidth within which most natural and artificial ambience occurs from each of said right and left channel inputs, said modified signal being passed to said modified right and said modified left channel outputs; means for combining said right and said left signal channel inputs to produce a signal which is passed to a center channel output.

Claim 18

An apparatus for enhancing the perceived sound image of a stereophonic, audio reproduction system having a right and a left channel signal inputs and a modified right, a modified left and a center signal channel outputs comprising: means for producing modified left and right signals where only audio information common to the right and left signal channel inputs is attenuated within a specified predetermined bandwidth within which most natural and artificial ambience occurs from each of said right and left channel inputs, said modified signal being passed to said modified right and said modified left channel outputs; means for combining said right and said left signal channel inputs to produce a signal which is passed to a center channel output.