Patent US4868878A successfully refreshed from Google Patents.
US4868878A
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Sound field correction system
Assignee: Pioneer Corp
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Filing: 1987-07-28
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Granted: 1989-09-19
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Expires: 2007-07-28
Abstract
Abstract A sound field correcting system for correcting for multipath frequency-characteristic distortion in an acoustic reproducing system. In one embodiment, the level and delay of an original signal are adjusted and superposed on the original signal so as to obtain a signal which, when reproduced by a loudspeaker, yields a sound pattern at a listening point having a flat frequency characteristic. The delay adjustment is effected in accordance with a difference between the travel distances of direct and reflected sound waves to the listening point.
Inventors
- 👤 Yoshiro Kunugi
- 👤 Akio Tokumo
- 👤 Toshikazu Yoshimi
- 👤 Yoshio Sasaki
- 👤 Shinjiro Kato
- 👤 Shuuichi Mori
- 👤 Makoto Odaka
- 👤 Takeshi Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:45
CPC Classifications
H; H04; H04S; H04S1/00; H04S1/002; H03; H03G; H03G5/00; H03G5/02; H03G5/04; H04R; H04R3/00; H04R3/04
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
214 words
A sound field correcting system for correcting a sound field formed by a combination of at least one direct sound wave radiated directly from at least a first loudspeaker and traveling a first distance to reach a listener and at least one reflected sound wave, also radiated from said at least said first loudspeaker and traveling a second, longer distance to reach said listener, said sound field correcting system comprising: delay means for delaying an original signal which is an electrical equivalent of said direct sound wave to provide a delayed signal as a function of said first and second distances; a high-pass filter for receiving said delayed signal and altering a frequency characteristic of said delayed signal to produce a filtered signal; level adjusting means for receiving said filtered signal and adjusting its level to produce an output signal which is an electrical equivalent of said reflected sound wave; and first adding means for superposing the output signal of said adjusting means on said original signal to obtain a first corrected signal for eliminating an effect of said at least one reflected sound wave at a predetermined listening point in said sound field, said superposing of said output signal of said adjusting means boosting a low frequency characteristic of said first corrected signal.
Claim 2
Dependent Claim
214 words
A sound field correcting system for correcting a sound field formed by a combination of at least one direct sound wave radiated directly from at least a first loudspeaker and traveling a first distance to reach a listener and at least one reflected sound wave, also radiated from said at least said first loudspeaker and traveling a second, longer distance to reach said listener, said sound field correcting system comprising: delay means for delaying an original signal which is an electrical equivalent of said direct sound wave to provide a delayed signal as a function of said first and second distances; a high-pass filter for receiving said delayed signal and altering a frequency characteristic of said delayed signal to produce a filtered signal; level adjusting means for receiving said filtered signal and adjusting its level to produce an output signal which is an electrical equivalent of said reflected sound wave; and first adding means for superposing the output signal of said adjusting means on said original signal to obtain a first corrected signal for eliminating an effect of said at least one reflected sound wave at a predetermined listening point in said sound field, said superposing of said output signal of said adjusting means boosting a low frequency characteristic of said first corrected signal.
Claim 3
Dependent Claim
19 words
A sound field correcting system as claimed in claim 1, wherein said high-pass filter has a variable frequency characteristic.
References Cited (Backward Citations)
US4309570A
Cited
US4308423A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-18 | 1993-03-20 | 1993-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-18 | 1997-03-20 | 1997-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-18 | 2001-03-20 | 2001-09-19 | $7700.00 | Window Closed / Lapsed |