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Patent US5440638A successfully refreshed from Google Patents.
US5440638A
Expired / Lapsed
US
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Stereo enhancement system
Assignee: J&C RESOURCES Inc
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Filing: 1993-09-03
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Granted: 1995-08-08
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Expires: 2013-09-03
Abstract
Abstract The sound field in a stereo reproduction system is enhanced by a preprocessor that removes a portion of the audio information that is common or substantially common to both the left and right stereo input signals before processing the signals in left and right sound placement filters. The left and right placement filter output signals, from which a portion of the common audio information was previously removed before processing, are added to the right and left stereo input signals, respectively, to produce enhanced sound field stereo output signals. The input signals that do not undergo placement processing are delayed in delay filters so that coherency is maintained when the signals are added and both the placement filters and the delay filters can be implemented by a series of cascaded bi-quadratic filters.
Inventors
- 👤 Danny D. Lowe
- 👤 Scott Willing
- 👤 William Gonnason
- 👤 Mark Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:26
CPC Classifications
H; H04; H04S; H04S1/00; H04S1/002
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
217 words
Stereo sound field enhancement apparatus for use in reproducing left and right stereophonic audio signals in a system employing left and right placement filters that alter the phase and amplitude of the signals on a predetermined frequency dependent basis, the apparatus comprising: first means receiving the left and right stereophonic audio signals for producing a left output signal from which substantially all audio information common to the right stereophonic audio signal is removed, said left output signal being fed to the right placement filter, and for producing a right output signal from which substantially all audio information common to the left stereophonic audio signal is removed, said right output signal being fed to the left placement filter; combining means for combining an output of the left placement filter and the right stereophonic audio signal to form an enhanced right-channel stereo signal and for combining an output of the right placement filter and the left audio signal to form an enhanced left-channel stereo signal; and a left-channel delay unit for delaying the left stereophonic audio signal fed to said combining means for combining with an output of said right placement filter, and a right-channel delay unit for delaying the right stereophonic audio signal fed to said combining means for combining with an output of said left placement filter.
Claim 2
Dependent Claim
217 words
Stereo sound field enhancement apparatus for use in reproducing left and right stereophonic audio signals in a system employing left and right placement filters that alter the phase and amplitude of the signals on a predetermined frequency dependent basis, the apparatus comprising: first means receiving the left and right stereophonic audio signals for producing a left output signal from which substantially all audio information common to the right stereophonic audio signal is removed, said left output signal being fed to the right placement filter, and for producing a right output signal from which substantially all audio information common to the left stereophonic audio signal is removed, said right output signal being fed to the left placement filter; combining means for combining an output of the left placement filter and the right stereophonic audio signal to form an enhanced right-channel stereo signal and for combining an output of the right placement filter and the left audio signal to form an enhanced left-channel stereo signal; and a left-channel delay unit for delaying the left stereophonic audio signal fed to said combining means for combining with an output of said right placement filter, and a right-channel delay unit for delaying the right stereophonic audio signal fed to said combining means for combining with an output of said left placement filter.
Claim 3
Dependent Claim
100 words
A stereo sound field enhancement apparatus according to claim 1, wherein said means for producing left and right output signals comprises a first inverter for inverting the left stereophonic audio signal and a first signal summing circuit receiving an inverted left stereophonic output signal from the first inverter and the right stereophonic audio signal for producing said right output signal; and a second inverter for inverting the right stereophonic audio signal and a second signal summing circuit receiving an inverted right stereophonic output signal from the second inverter and the left stereophonic audio signal for producing said left output signal.
Claim 4
Dependent Claim
53 words
A stereo sound field enhancement apparatus according to claim 2, wherein said means for producing left and right output signals further comprises a first controllable attenuator connected between said first inverter and said first signal summing circuit, and a second controllable attenuator connected between said second inverter and said second signal summing circuit.
Claim 5
Dependent Claim
38 words
A stereo sound field enhancement apparatus according to claim 3, further comprising third and fourth controllable attenuators receiving respectively said left and right output signals and producing attenuated signal respectively fed to the right and left placement filters.
Claim 6
Dependent Claim
53 words
A stereo sound field enhancement apparatus according to claim 4, further comprising fifth and sixth controllable attenuators receiving respectively the left and right stereophonic audio signals for producing attenuated left and right stereophonic audio signals fed to said combining means for combining respectively with said right output signal and said left output signal.
Claim 7
Dependent Claim
69 words
A stereo sound field enhancement apparatus according to claim 1, further comprising a left-channel equalization and compression filter receiving the left stereophonic audio signal for producing a filtered left-channel signal fed to said first means and said means for combining, and a right-channel equalization and compression filter receiving the right stereophonic audio signal for producing a filtered right-channel signal fed to said first means and said means for combining.
Claim 8
Dependent Claim
57 words
A stereo sound field enhancement apparatus according to claim 1, further comprising a left-channel controllable attenuator receiving the left stereophonic audio signal and producing a left-channel attenuated signal fed to said left-channel delay unit, and a right-channel controllable attenuator receiving the right stereophonic audio signal and producing a right-channel attenuated signal fed to said right-channel delay unit.
Claim 9
Dependent Claim
214 words
Stereo sound field enhancement apparatus for use in reproducing left and right stereophonic audio signals, the apparatus comprising: left and right placement filters that alter the phase and amplitude of signals fed thereto on a predetermined frequency dependent basis; first means receiving the left and right stereophonic audio signals for producing a left output signal from which substantially all audio information common to the right stereophonic audio signal is removed, said left output signal being fed to said right placement filter, and for producing a right output signal from which substantially all audio information common to the left stereophonic audio signal is removed, said right output signal being fed to said left placement filter; combining means for combining an output of said left placement filter and the right stereophonic audio signal to form an enhanced right-channel stereo signal and for combining an output of said right placement filter and the left audio signal to form an enhanced left-channel stereo signal; and a left-channel delay unit for delaying the left stereophonic audio signal fed to said combining means for combining with an output of said right placement filter, and a right-channel delay unit for delaying the right stereophonic audio signal fed to said combining means for combining with an output of said left placement filter.
Claim 10
Dependent Claim
214 words
Stereo sound field enhancement apparatus for use in reproducing left and right stereophonic audio signals, the apparatus comprising: left and right placement filters that alter the phase and amplitude of signals fed thereto on a predetermined frequency dependent basis; first means receiving the left and right stereophonic audio signals for producing a left output signal from which substantially all audio information common to the right stereophonic audio signal is removed, said left output signal being fed to said right placement filter, and for producing a right output signal from which substantially all audio information common to the left stereophonic audio signal is removed, said right output signal being fed to said left placement filter; combining means for combining an output of said left placement filter and the right stereophonic audio signal to form an enhanced right-channel stereo signal and for combining an output of said right placement filter and the left audio signal to form an enhanced left-channel stereo signal; and a left-channel delay unit for delaying the left stereophonic audio signal fed to said combining means for combining with an output of said right placement filter, and a right-channel delay unit for delaying the right stereophonic audio signal fed to said combining means for combining with an output of said left placement filter.
Claim 11
Dependent Claim
100 words
A stereo sound field enhancement apparatus according to claim 8, wherein said means for producing left and right output signals comprises a first inverter for inverting the left stereophonic audio signal and a first signal summing circuit receiving an inverted left stereophonic output signal from the first inverter and the right stereophonic audio signal for producing said right output signal; and a second inverter for inverting the right stereophonic audio signal and a second signal summing circuit receiving an inverted right stereophonic output signal from the second inverter and the left stereophonic audio signal for producing said left output signal.
Claim 12
Dependent Claim
53 words
A stereo sound field enhancement apparatus according to claim 9, wherein said means for producing left and right output signals further comprises a first controllable attenuator connected between said first inverter and said first signal summing circuit, and a second controllable attenuator connected between said second inverter and said second signal summing circuit.
Claim 13
Dependent Claim
38 words
A stereo sound field enhancement apparatus according to claim 10, further comprising third and fourth controllable attenuators receiving respectively said left and right output signals and producing attenuated signal respectively fed to said right and left placement filters.
Claim 14
Dependent Claim
51 words
A stereo sound field enhancement apparatus according to claim 11, further comprising fifth and sixth controllable attenuators receiving respectively the left and right stereophonic audio signals for producing attenuated left and right stereophonic audio signals fed to said combining means respectively with said right output signal and said left output signal.
Claim 15
Dependent Claim
57 words
A stereo sound field enhancement apparatus according to claim 8, further comprising a left-channel controllable attenuator receiving the left stereophonic audio signal and producing a left-channel attenuated signal fed to said left-channel delay unit, and a right-channel controllable attenuator receiving the right stereophonic audio signal and producing a right-channel attenuated signal fed to said right-channel delay unit.
Claim 16
Dependent Claim
69 words
A stereo sound field enhancement apparatus according to claim 8, further comprising a left-channel equalization and compression filter receiving the left stereophonic audio signal for producing a filtered left-channel signal fed to said first means and said means for combining, and a right-channel equalization and compression filter receiving the right stereophonic audio signal for producing a filtered right-channel signal fed to said first means and said means for combining.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-08-07 | 1999-02-06 | 1999-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-07 | 2003-02-06 | 2003-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-07 | 2007-02-06 | 2007-08-08 | $7700.00 | Window Closed / Lapsed |