Acoustic attenuation device with active double wall
First Claim
1. Acoustic attenuation device, comprising two substantially parallel plates defining a rectangularly shaped internal space therebetween, noise detection means arranged between the two plates, inverse noise emission means arranged between the two plates, and control means for controlling the inverse noise emission means in such a way as to minimize a quantity supplied by the noise detection means, wherein the inverse noise emission means comprise four actuators whose respective positions parallel to the plates correspond approximately to four points constituting the centers of respective sides of the rectangular shape of said internal space wherein the noise detection means comprise four sensors whose respective positions parallel to the plates correspond approximately to four points constituting the centers of respective sides of a rhombus whose vertices are the centers of the sides of the rectangular shape of said internal space, wherein the four actuators are controlled in phase, and wherein the quantity to be minimized is represented by the sum of the output signals of the four sensors.
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Abstract
An active double wall comprises two parallel plates defining a rectangular space. Four sensors are positioned between the plates so as to detect noises in said space, and four actuators are placed between the plates to emit counter-noises in the space. The actuators are phase-controlled by a control unit in order to minimize the sum of the outputs of the sensors. The actuators are respectively positioned at the centers of the sides of the rectangular space, and the sensors are respectively positioned at the centers of the sides of a rhombus whose vertices are the respective centers of the sides of the rectangular space, or vice-versa.
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Citations
17 Claims
- 1. Acoustic attenuation device, comprising two substantially parallel plates defining a rectangularly shaped internal space therebetween, noise detection means arranged between the two plates, inverse noise emission means arranged between the two plates, and control means for controlling the inverse noise emission means in such a way as to minimize a quantity supplied by the noise detection means, wherein the inverse noise emission means comprise four actuators whose respective positions parallel to the plates correspond approximately to four points constituting the centers of respective sides of the rectangular shape of said internal space wherein the noise detection means comprise four sensors whose respective positions parallel to the plates correspond approximately to four points constituting the centers of respective sides of a rhombus whose vertices are the centers of the sides of the rectangular shape of said internal space, wherein the four actuators are controlled in phase, and wherein the quantity to be minimized is represented by the sum of the output signals of the four sensors.
- 2. Acoustic attenuation device, comprising two substantially parallel plates defining a rectangularly shaped internal space therebetween, noise detection means arranged between the two plates, inverse noise emission means arranged between the two plates, and control means for controlling the inverse noise emission means in such a way as to minimize a quantity supplied by the noise detection means, wherein the noise detection means comprise four sensors whose respective positions parallel to the plates correspond approximately to four points constituting the centers of respective sides of the rectangular shape of said internal space, wherein the inverse noise emission means comprise four actuators whose respective positions parallel to the plates correspond approximately to four points constituting the centers of respective sides of a rhombus whose vertices are the centers of the sides of the rectangular shape of said internal space, wherein the four actuators are controlled in phase, and wherein the quantity to be minimized is represented by the sum of the output signals of the four sensors.
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11. An acoustic attenuation device comprising two substantially parallel plates defining a rectangularly shaped internal space therebetween, a plurality of noise sensors arranged between the two plates, a plurality of acoustic actuators arranged between the two plates, and control means for controlling the acoustic actuators so as to minimize a sum of output signals of the noise sensors, wherein the acoustic actuators are controlled in phase, and wherein material and dimensions of the two plates are chosen to satisfy at least one relationship selected from the group of relationships consisting of:
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Fc /(Lx Ly)2 >
800 and fmrm <
f200 /2, andFc /(Lx Ly)2 >
300 and fmrm <
f200 /2,wherein Fc, expressed in hertz, denotes one member selected from the group consisting of a critical frequency of one of the two plates and a larger of two respective critical frequencies of the two plates wherein the two plates are of different compositions, Lx and Ly, expressed in meters, are lengths of sides of a rectangular shape of internal space located between the two plates, fmrm is a resonant frequency of a mass-spring-mass system, comprising the two plates and medium located therebetween, and f200 is an eigenfrequency given by the formula F200 =C0 /max (Lx, Ly) where so denotes speed of sound in medium located between the two plates. - View Dependent Claims (12, 13, 14)
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15. An acoustic attenuation device comprising two substantially parallel plates defining a rectangularly shaped internal space therebetween, a plurality of noise sensors arranged between the two plates, a plurality of acoustic actuators arranged between the two plates, and control means for controlling the acoustic actuators so as to minimize a sum of output signals of the plurality of noise sensors and wherein the acoustic actuators are controlled in phase, reference signal sensor supplying a reference signal, and a band-pass filter to which the reference signal is applied, wherein output of the band-pass filter is subjected to an adaptive filtering with finite impulse response to control the acoustic actuators, the band-pass filter allowing frequencies between fmrm /2 and min(2 fmrm, f200) to pass, wherein
fmrm is a resonant frequency of a mass-spring-mass system comprising the two plates and medium located therebetween, and f200 is an eigenfrequency given by the formula f200 =C0 /max (Lx, Ly), where co denotes the speed of sound in medium located between the two plates, and Lx and Ly denote lengths of sides of a rectangular shape of internal space located between the two plates.
Specification