Patent US4044203A successfully refreshed from Google Patents.
US4044203A
Expired / Lapsed
US
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Active control of sound waves
Assignee: Noise Cancellation Technologies Inc
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Filing: 1975-08-25
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Granted: 1977-08-23
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Expires: 1995-08-25
Abstract
Abstract A sound wave propagated along a duct through a fluid contained in the duct is attenuated by generating sound waves from an array of sound sources spaced along the duct. Each source generates two waves travelling in opposite directions; those travelling in the same direction as the unwanted wave sum to give a resultant which interferes destructively with the unwanted wave, while those travelling in the opposite direction sum to give a negligible resultant. The source array may be operated in response to detection of the unwanted wave.
Inventors
- 👤 Malcolm Alexander Swinbanks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:18
CPC Classifications
F; F16; F16L; F16L55/00; F16L55/02; F16L55/033; F16L55/0333; G; G10; G10K; G10K11/00; G10K11/16; G10K11/175; G10K11/178; G10K11/1781; G10K11/17821; G10K11/17825; G10K11/1785; G10K11/17853; G10K11/17857; G10K11/17861; G10K11/1787; G10K11/17875; F05; F05D; F05D2200/00; F05D2200/10; F05D2200/11; F05D2220/00; F05D2220/30; F05D2220/32; F05D2220/323; F05D2260/00; F05D2260/96; F05D2260/962; G10K2210/00; G10K2210/10; G10K2210/107; G10K2210/109; G10K2210/112; G10K2210/128; G10K2210/1281; G10K2210/30; G10K2210/301; G10K2210/3011; G10K2210/3042; G10K2210/3046; G10K2210/321; G10K2210/3219; G10K2210/3229; G10K2210/50; G10K2210/506
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
137 words
A method of attenuating a sound wave propagating in a given direction along a duct through a fluid contained in the duct, the method comprising: generating sound waves from an array of similar sound sources located adjacent the wall of said duct respectively at different positions along said duct, each source generating a pair of sound waves which travel through said fluid in opposite directions along said duct from the position of that source; and controlling the operation of said array of sources to cause destructive interference to occur between the wave to be attenuated and the resultant of the waves generated by said sources and travelling in said given direction and simultaneously to cause the resultant of the waves generated by said sources and travelling in the direction opposite to said given direction to be negligible.
Claim 2
Independent Claim
137 words
A method of attenuating a sound wave propagating in a given direction along a duct through a fluid contained in the duct, the method comprising: generating sound waves from an array of similar sound sources located adjacent the wall of said duct respectively at different positions along said duct, each source generating a pair of sound waves which travel through said fluid in opposite directions along said duct from the position of that source; and controlling the operation of said array of sources to cause destructive interference to occur between the wave to be attenuated and the resultant of the waves generated by said sources and travelling in said given direction and simultaneously to cause the resultant of the waves generated by said sources and travelling in the direction opposite to said given direction to be negligible.
Claim 3
Dependent Claim
36 words
A method according to claim 1, in which the operation of said array of sources is controlled in response to the detection of sound waves propagated along said duct through said fluid in said given direction.
Claim 4
Dependent Claim
57 words
A method according to claim 2, in which said detection is effected by a sound detection system comprising an array of similar sound detectors located adjacent the wall of said duct respectively at different positions along said duct all of which positions are displaced from said array of sources in the direction opposite to said given direction.
Claim 5
Dependent Claim
28 words
A method according to claim 1, in which each of said sources comprises at least three discrete sound generating devices distributed symmetrically about the wall of said duct.
Claim 6
Dependent Claim
24 words
A method according to claim 1, in which the wave to be attenuated and the waves generated by said sources are all plane waves.
Claim 7
Independent Claim
132 words
An apparatus for use in attenuating sound waves propagating along a duct through a fluid contained in the duct, the apparatus comprising: an array of similar sound sources located adjacent the wall of said duct respectively at different positions along said duct, each source being capable of generating a pair of sound waves which travel through said fluid in opposite directions along said duct from the position of that source; and means for operating said array of sources to cause destructive interference to occur between the wave to be attenuated and the resultant of the waves generated by said sources and travelling in said given direction and simultaneously to cause the resultant of the waves generated by said sources and travelling in the direction opposite to said given direction to be negligible.
Claim 8
Independent Claim
132 words
An apparatus for use in attenuating sound waves propagating along a duct through a fluid contained in the duct, the apparatus comprising: an array of similar sound sources located adjacent the wall of said duct respectively at different positions along said duct, each source being capable of generating a pair of sound waves which travel through said fluid in opposite directions along said duct from the position of that source; and means for operating said array of sources to cause destructive interference to occur between the wave to be attenuated and the resultant of the waves generated by said sources and travelling in said given direction and simultaneously to cause the resultant of the waves generated by said sources and travelling in the direction opposite to said given direction to be negligible.
Claim 9
Dependent Claim
52 words
An apparatus according to claim 6, in which said means for operating said array of sources comprises means for detecting sound waves propagated along said duct through said fluid in said given direction, and means for utilizing the output of said detecting means to control the operation of said array of sources.
Claim 10
Dependent Claim
51 words
An apparatus according to claim 7, in which said detecting means comprises an array of similar sound detectors located adjacent the wall of said duct respectively at different positions along said duct all of which positions are displaced from said array of sources in the direction opposite to said given direction.
Claim 11
Dependent Claim
28 words
An apparatus according to claim 6, in which each of said sources comprises at least three discrete sound generating devices distributed symmetrically about the wall of said duct.
Claim 12
Dependent Claim
16 words
An apparatus according to claim 6, in which said sources are operative to generate plane waves.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-22 | 1981-02-21 | 1981-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-22 | 1985-02-21 | 1985-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-22 | 1989-02-21 | 1989-08-23 | $7700.00 | Window Closed / Lapsed |