Classifications

• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
  • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
  • G10K11/1785—Methods, e.g. algorithms; Devices
  • G10K11/17857—Geometric disposition, e.g. placement of microphones
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
  • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
  • G10K11/1785—Methods, e.g. algorithms; Devices
  • G10K11/17853—Methods, e.g. algorithms; Devices of the filter
  • G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
  • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
  • G10K11/1787—General system configurations
  • G10K11/17879—General system configurations using both a reference signal and an error signal
  • G10K11/17881—General system configurations using both a reference signal and an error signal the reference signal being an acoustic signal, e.g. recorded with a microphone
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/102—Two dimensional
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/106—Boxes, i.e. active box covering a noise source; Enclosures
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/128—Vehicles
  • G10K2210/1282—Automobiles
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/10—Applications
  • G10K2210/129—Vibration, e.g. instead of, or in addition to, acoustic noise
  • G10K2210/1291—Anti-Vibration-Control, e.g. reducing vibrations in panels or beams
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/30—Means
  • G10K2210/301—Computational
  • G10K2210/3027—Feedforward
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/30—Means
  • G10K2210/301—Computational
  • G10K2210/3036—Modes, e.g. vibrational or spatial modes
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/30—Means
  • G10K2210/301—Computational
  • G10K2210/3046—Multiple acoustic inputs, multiple acoustic outputs
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/30—Means
  • G10K2210/321—Physical
  • G10K2210/3219—Geometry of the configuration
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
  • G10K2210/30—Means
  • G10K2210/321—Physical
  • G10K2210/3223—Materials, e.g. special compositions or gases

Definitions

• the present invention relates to an attenuation device type acoustic comprising two plates substantially parallels delimiting a rectangular space, noise detection means disposed between the two plates, counter-noise emission means arranged between the two plates, and regulating means for controlling the means for emitting noise abatements so as to to minimize a quantity supplied by the detection means noise.
• the invention has applications for example in the field of soundproofing of premises, in the realization hoods for noisy equipment, or in the insulation of passenger compartments of means of transport. An important application is in the realization of double glazing.
• This resonant frequency is generally between 50 and 250 Hz.
• the attenuation device aims to compensate for the low acoustic insulation provided by the double wall in the vicinity of f mrm .
• the principle consists in preventing - via an electro-acoustic system - any variation in volume of the air space.
• f L M n vs 0 2 ⁇ l ⁇ L x + m ⁇ L y + not ⁇ L z
• the variation in volume of the air gap is directly proportional to the amplitude of the mode (0,0,0) without the amplitude of the other modes in the vicinity of the resonance frequency of the wall f mrm being affected.
• the expression of the acoustic pressure given above (2) shows that the measurement carried out by a microphone will include the responses of other modes than the mode (0,0,0).
• the invention provides a device acoustic attenuation of the type indicated at the beginning, characterized in that the means for emitting noise abatements include four actuators with respective positions parallel to the plates correspond approximately in the middle of the sides of the rectangular shape of said interior space, in that the noise detection means include four sensors whose respective positions parallel to the plates correspond approximately at the four points on the longest sides of the rectangular shape of said interior space and distant each a quarter of the length of a long side relative at a corner of said rectangular shape, in that the four actuators are controlled in phase, and in that the quantity to be minimized is represented by the sum of output signals from the four sensors.
• the sensors and actuators practically do not interact with modes odd order of the space between the two plates (i.e. modes whose indices are of the type (l, m, n) with odd l or m), nor with the mode (2,0,0) which is the one with the lowest natural frequency among even order modes other than mode (0,0,0). So we can obtain satisfactory mode control (0,0,0) without significantly affect the effectiveness of mitigation by the excitement of natural low frequency modes.
• the respective positions of sensors and actuators are inverted, i.e. that the noise detection means comprise four sensors whose respective positions parallel to plates roughly correspond to the midpoints of sides of the rectangular shape of said interior space, and that the means of emission of noise abatement include four actuators with respective positions in parallel the plates correspond approximately to the four points located on the long sides of the rectangular shape of said interior space and each one quarter of the length of a large side with respect to a corner of said rectangular shape.
• the two embodiments above have the advantage that the sensors and actuators are located on the edges of the plates. This advantage is important when the plates are transparent or when the interplate space is not easily accessible (double wall prefabricated by example). It is not necessary to provide a structure particular between the plates to support the actuators or the sensors.
• the device shown in Figure 1 constitutes a active double wall usable to provide insulation acoustics between the spaces on either side of the wall.
• the wall includes two parallel rectangular plates 10, 11 delimiting between them an interior space 12 rectangular in shape.
• the plates are shown flat on the face. It will be understood, however, that they could have a certain curvature, while remaining substantially parallel.
• Sensors 13 and actuators 14 are arranged between the two plates 10, 11 for respectively detect the noise prevailing in space 12 and emit counter-noises in space 12.
• the sensors 13 and the actuators 14 are placed on the edges of the interior space 12.
• the arrangement of sensors 13 and actuators 14 parallel to the plates is illustrated in Figure 2.
• the actuators 14 are at number of four and arranged at the four points constituting the midpoints of the sides of the rectangular space 12.
• the sensors 13 are four in number and arranged each on a long side of the rectangular space 12, at a distance of one quarter the length of a long side with respect to a corner.
• the sensors 13 can be microphones with electrets chosen to have sensitivity characteristics and phase not varying more than 1% from one sensor to the other.
• the actuators 14 can be speakers.
• An example of a usable speaker is the AUDAX model BMX 400 which represents a good compromise between the flow volume and size (nominal power 15 W, resonance frequency of the order of 150 Hz, diameter outside 77.8 mm, total mass 290 g).
• a regulation unit 18 and provided for controlling the actuators 14 so as to minimize an error signal e provided by the sensors 13.
• the error signal to minimize consists of the amplified sum of the output signals of the four sensors 13, delivered by a summator 22.
• the control unit 18 includes a processing processor signal 23 programmed in a known manner to apply the gradient algorithm (LMS) with filtered reference.
• LMS gradient algorithm
• the coefficients of the filter are updated at each sampling cycle to minimize the error signal e.
• Processor 23 addresses then the same control signal to the actuators 14, so that the actuators 14 are controlled in phase.
• the resonance frequencies of the first modes air gap pairs (formula (2)) are given in Table I. (L M n) (2,0,0) (0.2.0) (2,2,0) (4,0,0) (4,2,0) f lmn (Hz) 216 290 362 434 522
• the sum of the output signals from the four sensors which represents the signal e to be minimized, reflects the response of the mode (0,0,0) of the space 12 located between the plates 10, 11.
• the error signal e there is practically no contribution of the odd order modes (l, m, n) with odd l or m taking into account the symmetrical arrangement of the sensors, nor of the even order mode of lowest natural frequency (2,0,0).
• the mode contributing to the signal e and having the lowest natural frequency is the mode (4,0,0) if L x ⁇ 2L y or the mode (0,2,0 ) if L x ⁇ 2L y .
• the natural frequency of this mode is relatively far from the resonance frequency f mrm , so that the influence of this mode and of higher index modes on the acoustic transmission is not decisive.
• the actuators controlled in phase hardly excite order modes odd, nor the modes (2,0,0) and (0,2,0). So the excitement actuators 14 mainly acts to compensate for the mode transmission (0,0,0) without significantly increasing the amplitudes of the other modes of low natural frequency.
• FIG. 3 shows the results of simulations of the acoustic attenuation provided by the device in FIG. 1 (without the filter 21) in the example of the parameters indicated above.
• the dashed line curve corresponds to the values of the attenuation index R as a function of the frequency f of the noise to be attenuated in the case where there is active mode control (0,0,0), and the curve in solid line corresponds to the same values in the absence of active control. It can be seen that the active control according to the invention appreciably increases the weakening index in the range of low frequencies close to the resonance frequency f mrm .
• the band-pass filter 21 is provided in the regulation unit 18. This filter 21, to which the reference signal is applied before the filtering with finite impulse response, allows the frequencies for which the mode control ( 0,0,0) has a favorable effect on the attenuation index, i.e.
• f200 c0 / max (L x , L y ), where c0 denotes the speed of the sound in the medium located between the two plates 10, 11.
• the space 12 located between the plates 10, 11 is occupied by a gas lighter than air.
• This increases the speed of the sound in the medium located between the plates, which decreases the density of the modes proper to the low frequencies (formula (4)), while the resonance frequency f mrm is only slightly modified.
• the relative contribution of the mode (0,0,0) to the acoustic transmission is then increased so that the efficiency of the active control of this mode is improved.
• This effect is all the more marked when the gas is light.
• Helium is therefore a preferred example for this gas. This effect also occurs for configurations of sensors and actuators other than that shown in FIG. 2.
• FIGS. 5A to 5F Examples of attenuation curves (index attenuation R as a function of frequency) obtained in simulating various constitutions of the plates are represented in FIGS. 5A to 5F which correspond respectively to the points A to F on the diagram in Figure 4.
• the curves at solid line illustrate the weakening index in the absence of active control, and the line curves interrupted illustrate the simulated loss index in subtracting the contribution from the mode (0,0,0).
• the plate configurations are shown in Table III below.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Building Environments (AREA)
• Exhaust Silencers (AREA)
• Filters That Use Time-Delay Elements (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=9468459

Family Applications (1)

Country Status (6)

Cited By (4)

Families Citing this family (21)

Citations (4)

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• 1994
  • 1994-11-03 FR FR9413125A patent/FR2726681B1/fr not_active Expired - Fee Related
• 1995
  • 1995-10-31 EP EP95402423A patent/EP0710946A1/fr not_active Withdrawn
  • 1995-11-02 US US08/551,951 patent/US5627897A/en not_active Expired - Fee Related
  • 1995-11-02 NO NO954391A patent/NO954391L/no unknown
  • 1995-11-02 FI FI955249A patent/FI955249A/sv not_active Application Discontinuation
  • 1995-11-06 JP JP7287456A patent/JPH0922292A/ja active Pending

Patent Citations (4)

Non-Patent Citations (1)

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