WO2022084913A1 - Apparatus and method for active noise cancellation in an enclosed environment - Google Patents

Apparatus and method for active noise cancellation in an enclosed environment Download PDF

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Publication number
WO2022084913A1
WO2022084913A1 PCT/IB2021/059720 IB2021059720W WO2022084913A1 WO 2022084913 A1 WO2022084913 A1 WO 2022084913A1 IB 2021059720 W IB2021059720 W IB 2021059720W WO 2022084913 A1 WO2022084913 A1 WO 2022084913A1
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WO
WIPO (PCT)
Prior art keywords
loudspeakers
active noise
noise cancellation
enclosed space
microphone
Prior art date
Application number
PCT/IB2021/059720
Other languages
French (fr)
Inventor
Mauro BURGO
Manuel MANZONI
Alberto Luigi COLOGNI
Ivo Emanuele Francesco Boniolo
Original Assignee
Esion S.R.L.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Esion S.R.L. filed Critical Esion S.R.L.
Publication of WO2022084913A1 publication Critical patent/WO2022084913A1/en

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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
    • G10K11/1787—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
    • G10K2210/12—Rooms, e.g. ANC inside a room, office, concert hall or automobile cabin
    • 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
    • G10K2210/3215—Arrays, e.g. for beamforming

Definitions

  • the present invention relates, in general, to devices and methods for active cancellation of noise in closed environments such as the room of a house.
  • the described apparatus uses a transparent film of piezoelectric polymer (PVDF) which has the advantage of being visually minimally invasive. Thanks to an array of reference microphones positioned outside the window, the device is able to dampen noise entering the window by appropriately vibrating the transparent film. Tests carried out on a 20cm x 20cm window produced average attenuations of 12 dB, for frequencies above 500 Hz.
  • the piezoelectric polymer has a very high cost which makes the adoption of the apparatus difficult. Furthermore, this apparatus is exclusively designed to be substituted for a window. Finally, the apparatus has a limited effectiveness at low frequencies.
  • the article "Open loop active control of noise through open windows”, Chuang Shi, Tatsuya Murao, Dongyuan Shi, Bhan Lam, and Woon-Seng Gan proposes a matrix of loudspeakers to be placed in a space left free by an opening of a window.
  • the speakers are controlled independently of each other in an open loop using a known noise cancellation algorithm.
  • an open-loop solution is difficult to reproduce in different environments and conditions, making the described solution difficult and expensive to implement.
  • the technical problem faced is therefore that of providing an apparatus and a method for the active cancellation of noise in closed environments that is economical and versatile.
  • the invention contemplates, for the apparatus, a plurality of loudspeakers, at least one internal microphone and means for processing and controlling the loudspeakers, wherein the processing and controlling means control the plurality of loudspeakers in a synchronous manner and according to an algorithm active noise cancellation so that said plurality of speakers emit a plane wave.
  • the invention contemplates a step of receiving a first signal representing noise entering a closed environment from at least one microphone and processing, as a function of this first signal, a first control signal identical for the plurality of speakers according to a closed-loop active noise cancellation algorithm for said plurality of speakers to emit a plane wave. This allows the apparatus and method for active noise cancellation to be simple to implement and easily adaptable to different environments and conditions thanks to significantly reduced setup costs.
  • the synchronous type control has the advantage of significantly reducing the hardware requirements for the execution of the method.
  • the use of a plane wave destructive interference is obtained in several points of the space. This allows to effectively dampen an incoming noise from flat surfaces that is distributed in a planar manner, as opposed to punctual abatement, for example in a confined space around the listener's ears. Thanks to the grid arrangement of the plurality of speakers, the visual impact of the system is particularly reduced. Therefore, the device may be easily applied to windows and walls without it creating a hindrance or an unpleasant aesthetic effect. In particular, in the case of applying the device to a window, there is advantageously a reduction of the incoming light of less than 2%.
  • Figure 1 shows a schematic view of a plurality of loudspeakers arranged on an XY matrix plane (one of the loudspeakers is shown enlarged by way of example only);
  • Figure 2 shows a schematic representation of an apparatus for active noise cancellation in an enclosed environment according to the present disclosure.
  • Figure 3 shows a block diagram of an active noise cancellation apparatus according to the present disclosure.
  • an apparatus for active noise cancellation in an enclosed environment comprises a plurality of speakers, at least one internal microphone and speaker processing and controlling means.
  • the loudspeakers are arranged according to a number m of rows having a direction parallel to a first X axis and a number n of columns having a direction parallel to a second Y axis, perpendicular to the first X axis. Furthermore, the plurality of loudspeakers lies on a XY matrix plane and is arranged perpendicular to a principal direction of an external noise to be dampened.
  • the loudspeakers are preferably arranged according to a number m of equidistant rows and according to a number n of equidistant columns, substantially arranged as an array.
  • This array of speakers can be applied, for example, to a wall from which external noise comes, or above a window.
  • the means for processing and controlling the loudspeakers are in data communication, via cable or wirelessly, with the microphone and with the plurality of loudspeakers.
  • these processing and controlling means control the loudspeakers synchronously or asynchronously, and / or with the same power or with power determined according to the position of each loudspeaker on the XY matrix plane and according to a closed-loop active noise cancellation algorithm so that the plurality of speakers emit a plane wave.
  • the internal microphone is of the directional type, that is, a microphone configured to detect noise coming from a single direction.
  • the internal directional microphone is placed at a certain distance from the plurality of speakers and directed towards them so as to detect noise entering perpendicularly inside the closed environment and attenuated by the apparatus, excluding as much as possible external disturbances, such as voices and noise produced inside the enclosed space or the reverberation sounds produced by the array of speakers.
  • the distance at which the directional microphone must be placed is preferably greater than the distance at which the plane wave is generated starting from the plurality of speakers, typically in the order of decimeters starting from the speakers.
  • control algorithm is of a known type and, in this regard, reference is made to the publication "Active Noise Control: A tutorial Review", S.M. Kuo; D.R. Morgan.
  • the algorithm is of the Broadband type with offline estimation of the secondary path, i.e. the transfer function between the signal acquired by the internal microphone and the signal actually emitted by the speaker array, so that the algorithm has an initial calibration phase.
  • each loudspeaker of the plurality of loudspeakers has a sound emission surface having a planar dimension lower than 3 cm 2 with respect to said matrix plane XY.
  • the plurality of loudspeakers has a density ranging from 90 to 110 loudspeakers per m 2 , even more preferably 100 per m 2 .
  • the apparatus for active noise cancellation also comprises at least one external microphone configured to detect noise outside the closed environment in correspondence with a noise source.
  • This external microphone is for example used in a feedforward algorithm to improve attenuation of noise obtained by this device.
  • the external microphone is also directional and placed in such a way as to detect noise entering the closed environment perpendicularly.
  • the method for active noise cancellation in an enclosed environment includes the following steps:
  • - providing a plurality of loudspeakers arranged according to a number m of rows having a direction parallel to a first axis X and a number n of columns having a direction parallel to a second axis Y, perpendicular to the first axis X, in which the plurality of loudspeakers lies on an XY matrix plane and is arranged perpendicular to a main direction of a noise source to be attenuated;
  • the algorithm is of the adaptive type, i.e. an algorithm that adapts the controller parameters over time in order to minimize the residual signal perceived by the internal microphone through a minimization algorithm.
  • the method includes the following further steps:
  • the method may comprise a further step of placing the plurality of loudspeakers in correspondence with a wall, a wall with a window, or only a window of said enclosed environment, affected by a source of external noise.
  • the method comprises a further initial step of self-calibration and estimation of the transfer function of the "secondary path”.
  • This initial step involves placing the internal microphone at a certain distance from the speaker grid, reproducing a white noise from the grid and, based on what is heard from the microphone, estimating the “secondary path”.
  • FIG. 3 A block diagram of an active noise cancellation apparatus according to the present disclosure is shown in Figure 3. It substantially comprises one or more microphones interfaced with a processing board, which receives electrical energy from a power supply, and which implements an algorithm for active noise cancellation. On the basis of the signals acquired by the microphones, the processing board determines how to drive the speakers (“speaker”) by generating suitable driving signals. These driving signals are amplified with a powered amplifier so as to be able to control the plurality of loudspeakers, typically arranged in a matrix (“grid”) to cancel, or at least reduce, the noise picked up by the microphones.
  • a powered amplifier so as to be able to control the plurality of loudspeakers, typically arranged in a matrix (“grid") to cancel, or at least reduce, the noise picked up by the microphones.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Circuit For Audible Band Transducer (AREA)

Abstract

Apparatus for active noise cancellation in an enclosed environment, such as a room with or without a window, comprising a plurality of loudspeakers, at least one internal microphone and speaker processing and controlling means, in which the processing and controlling means control the plurality of loudspeakers synchronously or asynchronously and according to an active noise cancellation algorithm so that said plurality of loudspeakers emits a plane wave.

Description

APPARATUS AND METHOD FOR ACTIVE NOISE CANCELLATION IN AN ENCLOSED
ENVIRONMENT
DESCRIPTION
Technical field of the invention
The present invention relates, in general, to devices and methods for active cancellation of noise in closed environments such as the room of a house.
Background
The article "Active Control of Sound Transmission Through Windows With Carbon Nanotube-Based Transparent Actuators", Xun Yu, Rajesh Rajamani, Kim A. Stelson, and Tianhong Cui, explores an apparatus for active noise reduction to be applied to a closed environment. The described apparatus uses a transparent film of piezoelectric polymer (PVDF) which has the advantage of being visually minimally invasive. Thanks to an array of reference microphones positioned outside the window, the device is able to dampen noise entering the window by appropriately vibrating the transparent film. Tests carried out on a 20cm x 20cm window produced average attenuations of 12 dB, for frequencies above 500 Hz.
However, the piezoelectric polymer has a very high cost which makes the adoption of the apparatus difficult. Furthermore, this apparatus is exclusively designed to be substituted for a window. Finally, the apparatus has a limited effectiveness at low frequencies.
The article "Open loop active control of noise through open windows", Chuang Shi, Tatsuya Murao, Dongyuan Shi, Bhan Lam, and Woon-Seng Gan proposes a matrix of loudspeakers to be placed in a space left free by an opening of a window. The speakers are controlled independently of each other in an open loop using a known noise cancellation algorithm. However, an open-loop solution is difficult to reproduce in different environments and conditions, making the described solution difficult and expensive to implement.
Summary of the invention
The technical problem faced is therefore that of providing an apparatus and a method for the active cancellation of noise in closed environments that is economical and versatile.
This problem is solved by an apparatus according to claim 1 and by a method according to claim 8.
Preferred features of the present invention are the subject of the dependent claims.
The invention contemplates, for the apparatus, a plurality of loudspeakers, at least one internal microphone and means for processing and controlling the loudspeakers, wherein the processing and controlling means control the plurality of loudspeakers in a synchronous manner and according to an algorithm active noise cancellation so that said plurality of speakers emit a plane wave. For the method, the invention contemplates a step of receiving a first signal representing noise entering a closed environment from at least one microphone and processing, as a function of this first signal, a first control signal identical for the plurality of speakers according to a closed-loop active noise cancellation algorithm for said plurality of speakers to emit a plane wave. This allows the apparatus and method for active noise cancellation to be simple to implement and easily adaptable to different environments and conditions thanks to significantly reduced setup costs.
Furthermore, the synchronous type control has the advantage of significantly reducing the hardware requirements for the execution of the method.
Thanks to the use of a plane wave, destructive interference is obtained in several points of the space. This allows to effectively dampen an incoming noise from flat surfaces that is distributed in a planar manner, as opposed to punctual abatement, for example in a confined space around the listener's ears. Thanks to the grid arrangement of the plurality of speakers, the visual impact of the system is particularly reduced. Therefore, the device may be easily applied to windows and walls without it creating a hindrance or an unpleasant aesthetic effect. In particular, in the case of applying the device to a window, there is advantageously a reduction of the incoming light of less than 2%.
Other advantages, characteristics and methods of use of the present invention will become evident from the following detailed description of some embodiments, presented by way of example and not of limitation.
Brief description of the figures
Reference will be made to the figure of the attached drawings, in which:
Figure 1 shows a schematic view of a plurality of loudspeakers arranged on an XY matrix plane (one of the loudspeakers is shown enlarged by way of example only);
Figure 2 shows a schematic representation of an apparatus for active noise cancellation in an enclosed environment according to the present disclosure; and
Figure 3 shows a block diagram of an active noise cancellation apparatus according to the present disclosure.
The sizes represented in the figures introduced above are intended as purely illustrative and are not necessarily shown in proportion. Detailed description of preferred embodiments
With reference to Figures 1 and 2, an apparatus for active noise cancellation in an enclosed environment, such as a room with or without a window, comprises a plurality of speakers, at least one internal microphone and speaker processing and controlling means.
The loudspeakers are arranged according to a number m of rows having a direction parallel to a first X axis and a number n of columns having a direction parallel to a second Y axis, perpendicular to the first X axis. Furthermore, the plurality of loudspeakers lies on a XY matrix plane and is arranged perpendicular to a principal direction of an external noise to be dampened.
According to one aspect, the loudspeakers are preferably arranged according to a number m of equidistant rows and according to a number n of equidistant columns, substantially arranged as an array. This array of speakers can be applied, for example, to a wall from which external noise comes, or above a window.
The means for processing and controlling the loudspeakers, for example a Digital Signal Processor, are in data communication, via cable or wirelessly, with the microphone and with the plurality of loudspeakers. Advantageously, these processing and controlling means control the loudspeakers synchronously or asynchronously, and / or with the same power or with power determined according to the position of each loudspeaker on the XY matrix plane and according to a closed-loop active noise cancellation algorithm so that the plurality of speakers emit a plane wave.
According to one aspect, the internal microphone is of the directional type, that is, a microphone configured to detect noise coming from a single direction. Preferably, the internal directional microphone is placed at a certain distance from the plurality of speakers and directed towards them so as to detect noise entering perpendicularly inside the closed environment and attenuated by the apparatus, excluding as much as possible external disturbances, such as voices and noise produced inside the enclosed space or the reverberation sounds produced by the array of speakers. The distance at which the directional microphone must be placed is preferably greater than the distance at which the plane wave is generated starting from the plurality of speakers, typically in the order of decimeters starting from the speakers.
The control algorithm is of a known type and, in this regard, reference is made to the publication "Active Noise Control: A Tutorial Review", S.M. Kuo; D.R. Morgan.
Preferably, the algorithm is of the Broadband type with offline estimation of the secondary path, i.e. the transfer function between the signal acquired by the internal microphone and the signal actually emitted by the speaker array, so that the algorithm has an initial calibration phase.
According to one aspect, each loudspeaker of the plurality of loudspeakers has a sound emission surface having a planar dimension lower than 3 cm2 with respect to said matrix plane XY. According to one aspect, the plurality of loudspeakers has a density ranging from 90 to 110 loudspeakers per m2, even more preferably 100 per m2.
According to one aspect, the apparatus for active noise cancellation also comprises at least one external microphone configured to detect noise outside the closed environment in correspondence with a noise source. This external microphone is for example used in a feedforward algorithm to improve attenuation of noise obtained by this device. Preferably, the external microphone is also directional and placed in such a way as to detect noise entering the closed environment perpendicularly.
The method for active noise cancellation in an enclosed environment includes the following steps:
- providing a plurality of loudspeakers arranged according to a number m of rows having a direction parallel to a first axis X and a number n of columns having a direction parallel to a second axis Y, perpendicular to the first axis X, in which the plurality of loudspeakers lies on an XY matrix plane and is arranged perpendicular to a main direction of a noise source to be attenuated;
- providing at least one microphone arranged inside the closed environment and configured to detect noise in the enclosed environment;
- receiving a first signal representing noise in the enclosed environment from the microphone and processing, as a function of this signal, at least one control signal, which can be identical or differentiated for each loudspeaker, for the plurality of loudspeakers according to a closed-loop active noise cancellation algorithm so that the plurality of speakers emits a plane wave. Preferably, the algorithm is of the adaptive type, i.e. an algorithm that adapts the controller parameters over time in order to minimize the residual signal perceived by the internal microphone through a minimization algorithm.
According to one aspect, the method includes the following further steps:
- providing at least one external microphone configured to detect noise outside the closed environment in correspondence with a noise source;
- receiving a second signal representing the external noise from the external microphone and modifying, as a function of this second signal, the control signal according to a feedforward algorithm.
It is to be understood that the method may comprise a further step of placing the plurality of loudspeakers in correspondence with a wall, a wall with a window, or only a window of said enclosed environment, affected by a source of external noise.
According to one aspect, the method comprises a further initial step of self-calibration and estimation of the transfer function of the "secondary path". This initial step involves placing the internal microphone at a certain distance from the speaker grid, reproducing a white noise from the grid and, based on what is heard from the microphone, estimating the “secondary path”.
A block diagram of an active noise cancellation apparatus according to the present disclosure is shown in Figure 3. It substantially comprises one or more microphones interfaced with a processing board, which receives electrical energy from a power supply, and which implements an algorithm for active noise cancellation. On the basis of the signals acquired by the microphones, the processing board determines how to drive the speakers ("speaker") by generating suitable driving signals. These driving signals are amplified with a powered amplifier so as to be able to control the plurality of loudspeakers, typically arranged in a matrix ("grid") to cancel, or at least reduce, the noise picked up by the microphones.
The present invention has been described up to now with reference to preferred embodiments. It is to be understood that there may be other embodiments that pertain to the same inventive core, as defined by the scope of the claims set out below.

Claims

1. An apparatus for active noise cancellation for indoor use in an enclosed space comprising:
- a plurality of loudspeakers arranged according to a number m of rows having a direction parallel to a first axis X and a number n of columns having a direction parallel to a second axis Y, perpendicular to the first axis X, said plurality of loudspeakers lying on a matrix plane XY and being arranged perpendicularly with respect to a main direction of an external noise to be attenuated;
- at least one internal microphone arranged inside said enclosed space and configured to detect noise in said enclosed space;
- control means for said loudspeakers in data communication with said at least one internal microphone and with said plurality of loudspeakers; characterized In that said control means are configured to control said speakers according to an active noise cancellation algorithm (ANC) so that said plurality of speakers emit a plane wave.
2. The apparatus for active noise cancellation according to the preceding claim, wherein said control means are configured to control each loudspeaker of said plurality of loudspeakers synchronously or asynchronously and/or with power determined according to a respective position in said XY matrix plane.
3. The apparatus for active noise cancellation according to any one of the preceding claims, wherein each loudspeaker of said plurality of loudspeakers has a sound emission surface having a planar dimension lower than 3 cm2 with respect to said XY matrix plane.
4. The apparatus for active noise cancellation according to any one of the preceding claims, wherein said plurality of loudspeakers has a density comprised between 90 and 110 loudspeakers per m2.
5. The apparatus for active noise cancellation according to any of the preceding claims, comprising at least one external microphone configured to detect noise coming from outside said enclosed space, at a source of said noise.
6. The apparatus for active noise cancellation according to any one of the preceding claims, wherein said loudspeakers are arranged according to a number m of equally spaced rows and according to a number n of equally spaced columns.
7. The apparatus for active noise cancellation according to any one of the preceding claims, wherein said at least one internal microphone is of the directional type, directed perpendicular to said matrix plane XY, facing said plurality of loudspeakers, and placed at a distance from said matrix plane XY greater than the distance at which the plane wave is generated starting from the plurality of loudspeakers.
8. The apparatus for active noise cancellation according to claim 5, wherein said at least one external microphone is of the directional type, directed perpendicularly with respect to said XY matrix plane, facing opposite to said plurality of loudspeakers.
9. A method for active noise cancellation in an enclosed space comprising the following steps:
- providing a plurality of loudspeakers arranged according to a number m of rows having a direction parallel to a first axis X and a number n of columns having a direction parallel to a second axis Y, perpendicular to the first axis X, said plurality of loudspeakers lying on an XY matrix plane and arranged perpendicular to a main direction of a noise source to be attenuated;
- providing at least one microphone disposed inside said enclosed space and configured to detect noise in said enclosed space;
- receiving a first signal representing the noise in said enclosed space from said at least one microphone and producing, as a function of said first signal, at least one first control signal for the plurality of loudspeakers according to an active noise cancellation algorithm (ANC: active noise control ) with closed loop so that said plurality of loudspeakers emit a plane wave;
- controlling said speakers with said first control signal to emit said plane wave.
10. The method for active noise cancellation according to claim 7, comprising the following further steps:
- providing at least one external microphone configured to detect noise outside said enclosed space at a source of said noise;
- receiving a second signal representing the external noise from said at least one external microphone and modifying, as a function of said second signal, said first control signal according to a feedforward algorithm
11. The method for active noise cancellation according to claim 7 or 8, comprising the following further steps:
- placing said plurality of loudspeakers in correspondence with a wall of said enclosed space affected by a source of said external noise.
12. The method for active noise cancellation according to claim 7 or 8, comprising the following further steps:
- placing said plurality of loudspeakers in correspondence with a window of said enclosed space affected by a source of said external noise.
13. The method for active noise cancellation according to any one of claims 9 to 12, comprising the operation of generating said single control signal to synchronously control all said loudspeakers.
14. The method for active noise cancellation according to any one of claims 9 to 12, comprising the operation of generating a plurality of said control signals to drive said loudspeakers asynchronously and/or to drive each loudspeaker of said loudspeakers with power determined as a function of a respective position in said XY matrix plane.
PCT/IB2021/059720 2020-10-22 2021-10-21 Apparatus and method for active noise cancellation in an enclosed environment WO2022084913A1 (en)

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IT102020000025033A IT202000025033A1 (en) 2020-10-22 2020-10-22 APPARATUS AND METHOD FOR THE ACTIVE CANCELLATION OF NOISE IN A CLOSED ENVIRONMENT

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002095725A1 (en) * 2001-05-21 2002-11-28 Valtion Teknillinen Tutkimuskeskus A construction for active sound attenuation
CN106639013A (en) * 2016-11-28 2017-05-10 南京大学 Mixed soundproof wall
US20190147846A1 (en) * 2016-06-17 2019-05-16 Oaswiss Ag Planar element for the active compensation of noise in an interior room and anti-noise module therefor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002095725A1 (en) * 2001-05-21 2002-11-28 Valtion Teknillinen Tutkimuskeskus A construction for active sound attenuation
US20190147846A1 (en) * 2016-06-17 2019-05-16 Oaswiss Ag Planar element for the active compensation of noise in an interior room and anti-noise module therefor
CN106639013A (en) * 2016-11-28 2017-05-10 南京大学 Mixed soundproof wall

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