Apparatus and method for active control of sound transmission through aircraft fuselage walls
First Claim
1. A system for attenuating noise in a cabin of an aircraft, the aircraft having an interior wall defining the cabin, and an exterior fuselage defining a trim panel cavity between the fuselage and the interior wall, the system comprising a plurality of acoustically active cells mounted in the trim panel cavity, and an electroacoustical sensor and an acoustical driver mounted within each cell, wherein a distance between the sensor and the driver is less than a distance between adjacent cells, and wherein the sensor transduces sound pressure in the cavity to produce an electrical signal which is inversely fed back to the driver to reduce sound pressure around the cell without a reference microphone.
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Accused Products
Abstract
In aircraft, much of the noise in the cabin is a result of pressure fluctuations on the exterior fuselage skin, which vibrates the skin and causes sound pressure waves to propagate through the trim panel cavity, exciting the trim panels, which radiate into the cabin. In the present invention, noise is reduced in the cabin of an aircraft by reducing the acoustical impedance of the trim panel cavity of the aircraft using an array of independent active sound absorbing acoustic cells. Acoustical drivers are mounted within the trim panel cavity of the aircraft. Each acoustical driver has at least one electroacoustical sensor mounted in its immediate vicinity. The sensor is connected to the driver to provide negative feedback, which has the effect of canceling noise in the vicinity of each cell. Since the effect of each cell is to absorb acoustical energy, the acoustical impedance of the trim panel cavity is reduced. Multiple sound absorbing acoustic cells in the trim panel cavity therefore decrease the acoustical impedance inside the trim panel cavity which in turn reduces the transmission of noise into the cabin.
21 Citations
6 Claims
- 1. A system for attenuating noise in a cabin of an aircraft, the aircraft having an interior wall defining the cabin, and an exterior fuselage defining a trim panel cavity between the fuselage and the interior wall, the system comprising a plurality of acoustically active cells mounted in the trim panel cavity, and an electroacoustical sensor and an acoustical driver mounted within each cell, wherein a distance between the sensor and the driver is less than a distance between adjacent cells, and wherein the sensor transduces sound pressure in the cavity to produce an electrical signal which is inversely fed back to the driver to reduce sound pressure around the cell without a reference microphone.
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5. A system for attenuating noise in a cabin of an aircraft, the aircraft having an interior wall defining the cabin, and an exterior fuselage defining a trim panel cavity between the fuselage and the interior wall, the system comprising a plurality of acoustically active cells mounted in the trim panel cavity, wherein each acoustically active cell comprises:
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means for transducing sound pressure in the vicinity of a driver of a sound pressure source in the cavity to provide an electrical signal; and means for inversely feeding back the electrical signal to the driver without a reference microphone; wherein a distance between the means for transducing sound pressure and the driver is less than a distance between the adjacent acoustically active cells, and wherein each acoustically active cell reduces sound pressure around the cell.
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6. A process for attenuating noise in a cabin of an aircraft, the aircraft having an interior wall defining the cabin, and an exterior fuselage defining a trim panel cavity between the fuselage and the interior wall, a plurality of acoustically active cells in the cavity, each cell having an electroacoustical sensor and an acoustical driver, a distance between the sensor and the driver being less than a distance between the adjacent cells, the process comprising the steps of:
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for each of the cells transducing sound pressure with the sensor in the vicinity of the driver to provide an electrical signal; and for each of the cells inversely feeding back the electrical signal to the driver without a reference microphone.
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Specification