CN112885324A - Control device and method for reducing noise inside mute cabin - Google Patents

Control device and method for reducing noise inside mute cabin Download PDF

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Publication number
CN112885324A
CN112885324A CN202110285773.9A CN202110285773A CN112885324A CN 112885324 A CN112885324 A CN 112885324A CN 202110285773 A CN202110285773 A CN 202110285773A CN 112885324 A CN112885324 A CN 112885324A
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Prior art keywords
noise
signal
error
microphone
mute
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Chinese (zh)
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殷艺敏
郑建辉
刘祖德
邵琳
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Guangzhou Soundbox Acoustic Tech Co ltd
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Guangzhou Soundbox Acoustic Tech Co ltd
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Priority to CN202110285773.9A priority Critical patent/CN112885324A/en
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    • 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
    • G10K11/1781—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17813—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms
    • 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
    • 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
    • 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

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

The application relates to a controlling means for reducing inside noise of silence cabin, this controlling means is applied to the silence cabin, and there is the inside of noise source silence cabin in the outside of silence cabin including the inside sound cavity that is full of by the air of cavity, and this controlling means includes noise active control ware, secondary sound source, error microphone and reference microphone, wherein: the noise active controller comprises a first input end, a second input end and an output end, wherein an error microphone is connected to the first input end, a reference microphone is connected to the second input end, and a secondary sound source is connected to the output end; the reference microphone is arranged on the outer wall of the mute cabin, and the noise active controller, the error microphone and the secondary sound source are arranged on the inner wall of the mute cabin and are not overlapped in position. By adopting the control device, the second noise can be offset in a sound silencing mode, and the sound insulation effect of the mute cabin is improved under the condition that the thickness of the wall of the mute cabin is not required to be increased.

Description

Control device and method for reducing noise inside mute cabin
Technical Field
The present invention relates to the field of noise control, and in particular, to a control device and method for reducing noise inside a mute cabin.
Background
The mute cabin is applied to a noisy environment with larger noise, and a quiet working or rest environment is provided for a user by a mode of sound insulation through the totally-closed cabin wall. In order to obtain a good noise reduction effect for the mute chamber, generally speaking, the lower the noise frequency, the greater the thickness of the chamber wall is required.
At present, the mute chamber on the market still gives priority to improving the sealing performance, preventing sound leakage and sound insulation of medium and high frequency, and in addition, the thickness of the chamber wall and the glass chamber door of the mute chamber cannot be too large due to cost considerations or other use limitations such as weight, so that the sound insulation effect on partial noise, especially low frequency noise, is not ideal.
Disclosure of Invention
In view of the above, it is necessary to provide a control device and method for reducing noise inside a mute cabin, which can improve a sound insulation effect against low-frequency noise, in view of the above technical problems.
A control device for reducing noise inside a mute compartment, the control device being applied to a mute compartment, a source of noise being present outside the mute compartment, the interior of the mute compartment comprising a sound cavity filled with air inside the cavity, the device comprising a noise active controller, a secondary sound source, an error microphone and a reference microphone, wherein:
said noise active controller comprising a first input, a second input and an output, said error microphone being connected to said first input, said reference microphone being connected to said second input, said secondary sound source being connected to said output;
the reference microphone is arranged on the outer wall of the mute cabin, and the noise active controller, the error microphone and the secondary sound source are all arranged on the inner wall of the mute cabin and are not overlapped in position;
the reference microphone is used for receiving first noise propagated by the noise source and inputting the reference electric signal to the noise active controller when the first noise is converted into a reference electric signal;
the error microphone is used for receiving second noise transmitted by the sound cavity when the sound cavity is excited, and inputting the error electric signal to the noise active controller when the second noise is converted into an error electric signal;
the noise active controller is used for outputting a white noise signal to the secondary sound source and calculating to obtain a transfer function according to the white noise signal and the error signal; calculating to obtain a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function;
and the secondary sound source is used for receiving the secondary signal and sending corresponding secondary sound waves to the error microphone, and the secondary sound waves are used for offsetting the generated second noise.
In one embodiment, the number of the reference microphones is adapted to the number of the noise sources;
the first installation positions of the reference microphones on the outer wall of the mute cabin respectively correspond to different first propagation directions, and the first propagation directions represent the directions of the noise source for propagating first noise.
In one embodiment, the number of the secondary sound sources and the number of the error microphones are both adapted to the number of the sound modes of the generated second noise corresponding to the sound cavity being excited;
a second mounting position of each error microphone on the inner wall of the mute cabin corresponds to a different second propagation direction, and the second propagation direction represents a direction in which the sound cavity is excited to correspondingly propagate second noise;
and the third mounting position of the secondary sound source on the inner wall of the mute cabin is matched with the second mounting position so as to ensure that when the sound cavity is excited, the first noise is counteracted through the secondary sound wave transmitted by the secondary sound source.
In one embodiment, neither the second mounting location nor the third mounting location includes an acoustic modal node.
In one embodiment, the operating frequency ranges of the secondary sound source, the error microphone, and the reference microphone each include an operating frequency range of controlled noise that characterizes noise propagating via the noise source to the interior of the mute compartment.
A control method for reducing noise inside a mute cabin, the method being applied to the control device of any one of the above, comprising:
receiving a first noise propagated by the noise source through the reference microphone, and inputting a reference electric signal to the noise active controller when converting the first noise into the reference electric signal;
when the sound cavity is excited, receiving second noise transmitted by the sound cavity through the error microphone, and when the second noise is converted into an error electric signal, inputting the error electric signal to the noise active controller;
outputting a white noise signal to the secondary sound source through the noise active controller, and calculating to obtain a transfer function according to the white noise signal and an error signal; calculating to obtain a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function;
and receiving the secondary signal by the secondary sound source, and sending a corresponding secondary sound wave to the error microphone, wherein the secondary sound wave is used for offsetting the generated second noise.
In one embodiment, before receiving the first noise propagated by the noise source through the reference microphone, the method further comprises:
confirming the number of noise sources arranged outside the mute cabin and the direction of the noise sources for transmitting the first noise;
when the acoustic cavity is excited, confirming the quantity of the second noise generated currently and the direction of the second noise by an acoustic testing instrument;
determining the number of the reference microphones according to the number of the noise sources, and determining the number of the secondary sound sources and the number of the error microphones according to the number of the sound modes of the second noise generated currently;
determining a first mounting position of each reference microphone on the outer wall of the mute cabin according to the direction of the first noise transmitted by the noise source;
and determining a second mounting position of each error microphone on the inner wall of the mute cabin according to the propagation direction of the second noise and the shape of the acoustic mode, and determining a third mounting position of each secondary sound source on the inner wall of the mute cabin according to the determined second mounting position.
In one embodiment, before receiving the first noise propagated by the noise source through the reference microphone, the method further comprises:
confirming the sound wave frequency of the second noise generated currently by an acoustic testing instrument when the sound cavity is excited;
and respectively confirming effective working frequency ranges of the reference microphone, the error microphone and the secondary sound source according to the sound wave frequency so as to ensure that the effective working frequencies of the reference microphone, the error microphone and the secondary sound source comprise the sound mode frequency.
In one embodiment, the calculating a transfer function according to the white noise signal and the error signal includes:
Figure BDA0002980394820000041
wherein the content of the first and second substances,
Figure BDA0002980394820000042
refers to the transfer function, e (Z) refers to the error signal, and x (Z) refers to the white noise signal.
In one embodiment, the calculating a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function includes:
y(n)＝xin(n)*w(n)；
Figure BDA0002980394820000043
wherein y (n) denotes a secondary signal, xin(n) refers to the reference signal, w (n) refers to the first adaptive filter coefficients of the noise active controller; mu refers to an iteration coefficient, w (n +1) refers to a second adaptive filter coefficient corresponding to the current noise active controller when the next iteration is started; e (n) refers to the error signal,
Figure BDA0002980394820000044
refers to the impulse response corresponding to the transfer function.
The control device and the method for reducing the noise inside the mute cabin receive the first noise propagated by the noise source through the reference microphone arranged on the outer wall of the mute cabin, and receive the second noise generated inside the mute cabin through the error microphone arranged on the inner wall of the mute cabin. The received noise signal is further transmitted to the noise active controller, and the noise active controller performs transfer function calculation based on the output white noise signal and the received second noise signal (i.e., the error signal), so that the cancellation effect of the secondary sound wave is improved under the condition that the sound propagation channel from the secondary sound source to the error microphone is accurately determined. And calculating, by the noise active controller, a secondary signal to be output to the secondary sound source based on the received first noise signal (i.e., the reference signal), the error signal, and the transfer function. Finally, the secondary signal is received by the secondary sound source, and the corresponding secondary sound wave is sent to the error microphone, so that the second noise can be offset in a sound silencing mode, and the sound insulation effect of the mute cabin is improved under the condition that the thickness of the wall of the mute cabin does not need to be increased.
Drawings
FIG. 1 is a schematic structural diagram of a control device for reducing noise inside a mute compartment according to an embodiment;
FIG. 2 is a schematic flow chart of a control method for reducing the noise inside a mute chamber according to one embodiment;
FIG. 3 is a schematic diagram of the operation of a control device for reducing noise inside a mute compartment according to an embodiment;
FIG. 4 is a schematic diagram of the calculation of a transfer function in one embodiment;
fig. 5 is a flowchart illustrating a control method for reducing the noise inside the mute compartment in another embodiment.
In the attached figure 1: 1-noise active controller; 2-a secondary sound source; 3-an error microphone; 4-a reference microphone; 5-mute chamber.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In one embodiment, as shown in fig. 1, there is provided a control device for reducing noise inside a mute compartment, the control device being applied to a mute compartment 5, a noise source being present outside the mute compartment 5, the inside of the mute compartment 5 including a sound cavity filled with air inside the cavity, the device including a noise active controller 1, a secondary sound source 2, an error microphone 3 and a reference microphone 4, wherein:
the noise active controller 1 comprises a first input 11, a second input 12 and an output 13, the error microphone 3 being connected to the first input 11, the reference microphone 4 being connected to the second input 12, and the secondary sound source 2 being connected to the output 13.
The reference microphone 4 is arranged on the outer wall of the mute chamber 5, and the noise active controller 1, the error microphone 3 and the secondary sound source 2 are all arranged on the inner wall of the mute chamber 5 and are not overlapped in position.
Specifically, the number and mounting positions of the reference microphones 4 are determined by:
the number of the reference microphones 4 is adapted to the number of the noise sources; the first installation positions of the individual reference microphones 4 on the outer wall of the quiet compartment 5 correspond to different first propagation directions, wherein the first propagation directions represent the directions in which the noise sources propagate the first noise.
In one embodiment, the number and specific mounting positions of the reference microphones 4 are determined according to the noise environment outside the mute compartment 5. Wherein:
(1) the number of reference microphones 4 should not be less than the number of noise sources controlled outside the mute compartment 5 and the number of reference microphones is at least 1. It is understood that when the mute compartment is in a noisy environment where multiple noise sources, such as fan noise, low frequency noise of a truck engine, etc., are mixed together, the number of current reference microphones is at least 2.
(2) Referring to the specific installation position of the microphone 4 on the mute chamber 5, it should be located on the outer wall of the mute chamber 5 or an accessory provided on the outer wall of the mute chamber 5 for controlling the direction of the noise source. For example, when the noise source to be controlled outside the mute compartment 5 is located in the south direction, the reference microphone 4 should be mounted on the outer wall of the south side of the mute compartment or an attachment to the outer wall provided on the south side of the mute compartment). For example, in the case where the mute compartment 5 is in a noise environment where a plurality of noise sources such as fan noise, low-frequency noise of a truck engine, and the like are mixed together, the specific installation position of the reference microphone 4 may be divided into an outer wall of the mute compartment in the direction of the source of the fan noise and the engine noise.
In the above embodiment, the installation positions of the reference microphone and the error microphone are adaptively set according to the propagation of the controlled noise outside the mute cabin and the propagation direction of the second noise inside the mute cabin, so that the noise signal reception processing in different noise propagation directions outside or inside different mute cabins is effectively ensured, the efficiency of identifying and receiving the target noise is improved, and a good basis is laid for the subsequent calculation of the transfer function.
Specifically, the number and mounting positions of the secondary sound sources 2 and the error microphones 3 are determined by:
the number of the secondary sound sources 2 and the number of the error microphones 3 are both adapted to the number of the sound modes of the second noise generated by the corresponding excited sound cavity; the second installation position of each error microphone 3 on the inner wall of the mute chamber 5 corresponds to a different second propagation direction, wherein the second propagation direction represents the direction in which the sound cavity is excited to correspondingly propagate second noise; the third installation position of the secondary sound source 2 on the inner wall of the mute compartment 5 is adapted to the second installation position to ensure that the first noise cancellation is performed by the secondary sound waves propagated via the secondary sound source 2 when the acoustic cavity is excited.
Specifically, the second mounting position and the third mounting position do not include the acoustic modal node.
In one of the embodiments, the number and mounting positions of the secondary sound sources 2 and the error microphones 3 are determined according to the noise environment inside the mute compartment 5, wherein:
(1) the number of the secondary sound sources 2 and the error microphones 3 is determined according to the number of the acoustic mode number of the second noise generated when the sound cavity is excited and the acoustic mode shape, and the number is at least 1. It should be noted that, when the number of generated acoustic modes is larger and the distribution of the shapes of the respective acoustic modes is more complicated, the number of the required secondary acoustic sources and error microphones is larger.
(2) In consideration of monitoring effect, the mounting positions of the secondary sound source 2 and the error microphone 3 should be as close as possible to the antinodal plane of the acoustic cavity mode inside the mute cabin to be counteracted so as to avoid being placed at the excited acoustic mode node. Wherein, the installation position of the secondary sound source 2 on the mute chamber is limited at the wall surface direction where the noise source comes.
Specifically, the operating frequency ranges of the secondary sound source, the error microphone, and the reference microphone all include an operating frequency range of controlled noise that characterizes noise propagating through the noise source to the interior of the mute compartment.
When the noise in the mute cabin is reduced, the implementation functions of all the components of the control device are as follows:
and a reference microphone 4 for receiving the first noise propagated from the noise source and inputting the reference electric signal to the noise active controller when converting the first noise into the reference electric signal.
The position of the reference microphone can be kept consistent with the position of the first noise propagated by the noise source, so that the reference microphone can be ensured to be accurate, the first noise propagated by the noise source in each position is received with a small error, and the first noise is transmitted to the noise active controller when being converted into a reference electric signal.
And the error microphone 3 is used for receiving the second noise propagated by the sound cavity when the sound cavity is excited, and inputting the error electric signal to the noise active controller when the second noise is converted into the error electric signal.
And/or when the noise active controller outputs white noise and excites the sound cavity, receiving second noise propagated by the sound cavity, and when the second noise is converted into an error electric signal by the error microphone, inputting the error electric signal to the noise active controller, and further processing by the noise active controller.
The noise active controller 1 is used for outputting a white noise signal to the secondary sound source and calculating to obtain a transfer function according to the white noise signal and the error signal; and calculating to obtain a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function.
When the noise active controller outputs a white noise signal to the secondary sound source, the currently output white noise signal further excites the sound cavity to generate second noise, and currently, the noise active controller further calculates a transfer function according to the received error signal and the generated white noise signal. It should be noted that the transfer function is characterized by a transfer function of a secondary channel, where the secondary channel refers to an acoustic propagation channel required for propagating a secondary sound wave from a secondary sound source to the error microphone, and the transfer function reflects a change of the secondary sound wave after the secondary sound wave propagates through the channel, such as a change of an amplitude and a phase.
And the secondary sound source 2 is used for receiving the secondary signal and sending a corresponding secondary sound wave to the error microphone, and the secondary sound wave is used for offsetting the generated second noise.
Wherein the secondary sound source is caused to propagate a secondary sound wave having the same amplitude as the second noise but opposite phase to the second noise, based on canceling the generated second noise in an acoustically muffled manner. At present, under the condition that the wall thickness of the mute cabin is not required to be increased, the sound insulation capability of the mute cabin on low-frequency noise is improved in a sound silencing mode, and the sound insulation and noise reduction effects of the mute cabin are improved.
In the control device for reducing the noise inside the mute cabin, a first noise propagated from a noise source is received by a reference microphone provided on an outer wall of the mute cabin, and a second noise generated inside the mute cabin is received by an error microphone provided on an inner wall of the mute cabin. The received noise signal is further transmitted to the noise active controller, and the noise active controller performs transfer function calculation based on the output white noise signal and the received second noise signal (i.e., the error signal), so that the cancellation effect of the secondary sound wave is improved under the condition that the sound propagation channel from the secondary sound source to the error microphone is accurately determined. And calculating, by the noise active controller, a secondary signal to be output to the secondary sound source based on the received first noise signal (i.e., the reference signal), the error signal, and the transfer function. And finally, receiving the secondary signal by a secondary sound source, and sending corresponding secondary sound waves to the error microphone, so that the second noise can be offset in a sound silencing mode, and the sound insulation effect of the mute cabin is improved under the condition that the thickness of the cabin wall of the mute cabin is not required to be increased.
In one embodiment, as shown in fig. 2, a control method for reducing noise inside a mute cabin is provided, and the method is applied to the control device, and includes the following steps:
step S202, receiving the first noise propagated by the noise source through the reference microphone, and inputting the reference electrical signal to the noise active controller when converting the first noise into the reference electrical signal.
Specifically, before receiving the first noise propagated by the noise source through the reference microphone, the method further includes: confirming the number of noise sources arranged outside the mute cabin and the direction of the noise sources for transmitting the first noise; when the acoustic cavity is excited, confirming the quantity of the second noise generated currently and the direction of the second noise by an acoustic testing instrument; determining the number of reference microphones according to the number of noise sources, and determining the number of secondary sound sources and error microphones according to the number of sound modes of second noise generated currently; determining a first mounting position of each reference microphone on the outer wall of the mute cabin according to the direction of the first noise transmitted by the noise source; determining a second mounting position of each error microphone on the inner wall of the mute compartment according to the propagation direction of the second noise and the shape of the acoustic mode, and determining a third mounting position of each secondary sound source on the inner wall of the mute compartment according to the determined second mounting position.
It should be noted that neither the second mounting location nor the third mounting location includes an acoustic mode node.
In one embodiment, the number of noise sources used outside the mute chamber and the direction of the first noise transmitted by the noise sources can be confirmed by combining subjective evaluation and test analysis, and in an exemplary embodiment, the subjective evaluation can be performed by hearing and judging through human ears; for example, the test analysis may be performed by using a professional instrument, such as a noise imager, a sound intensity meter, and the like, which is not limited in this embodiment of the application.
In the above embodiment, before the reference microphone receives the first noise propagated by the noise source, the noise environments in and outside the mute cabin and the direction of the propagated noise are confirmed, so that the number and the installation positions of the reference microphone, the error microphone and the secondary sound source can be determined conveniently. For the generated second noise, a corresponding acoustic testing instrument may be adopted for detection and confirmation, and the embodiment of the present application does not limit the model and the type of the acoustic testing instrument used.
And step S204, receiving the second noise transmitted by the sound cavity through the error microphone when the sound cavity is excited, and inputting the error electric signal to the noise active controller when the second noise is converted into the error electric signal.
Step S206, outputting a white noise signal to a secondary sound source through a noise active controller, and calculating to obtain a transfer function according to the white noise signal and an error signal; and calculating to obtain a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function.
Specifically, referring to fig. 3, which is a schematic diagram illustrating a principle of calculating a transfer function in an embodiment, the transfer function is calculated according to a white noise signal and an error signal, and the method includes:
Figure BDA0002980394820000091
wherein the content of the first and second substances,
Figure BDA0002980394820000101
refers to the transfer function, e (Z) refers to the error signal, and x (Z) refers to the white noise signal.
In one embodiment, please refer to fig. 4, which is a schematic diagram illustrating an operation principle of the control device for reducing noise inside the mute cabin in one embodiment, and it can be seen from the schematic diagram that i noise sources are currently disposed outside the mute cabin, and first noise signals transmitted by the noise sources are respectively received by corresponding reference microphones. When receiving the error signal e (n) transmitted by the error microphone, the active noise controller calculates a transfer function by using the above formula (1), which is to say, the transfer function of the secondary channel, wherein the secondary channel can be further understood as an acoustic propagation channel from the secondary source to the error microphone. The transfer function will further reflect the variation of the noise after propagation in the channel, such as the amplitude and phase variation.
In one embodiment, calculating a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function includes:
y(n)＝xin(n)*w(n)；
Figure BDA0002980394820000102
wherein y (n) denotes a secondary signal, xin(n) refers to a reference signalThe number w (n) refers to the first adaptive filter coefficients of the noise active controller; mu refers to an iteration coefficient, w (n +1) refers to a second adaptive filter coefficient corresponding to the current noise active controller when the next iteration is started; e (n) refers to the error signal,
Figure BDA0002980394820000103
refers to the impulse response corresponding to the transfer function.
And step S208, receiving the secondary signal through a secondary sound source, and sending a corresponding secondary sound wave to the error microphone, wherein the secondary sound wave is used for offsetting the generated second noise.
Wherein, on the one hand, the error microphone and the corresponding secondary sound source should ensure a certain distance therebetween in a direction following the propagation path of the secondary sound wave. It should be noted that the specific distance should be determined according to the real-time operation speed of the active noise controller and the calculation amount of the adaptive algorithm (for example, the filtering-XLMS algorithm, the calculation amount may refer to the number of times of calculation such as addition, subtraction, multiplication, division, etc.), so as to ensure that the active noise controller has enough time to perform real-time signal processing and calculation. On the other hand, the secondary sound wave should have the same amplitude as the second noise and have a phase opposite to the phase of the second noise, so that the second noise generated in the mute chamber can be cancelled by means of sound attenuation, wherein the second noise may be at least one of low frequency noise and/or medium low frequency noise.
In the embodiment, under the condition that the wall thickness of the mute cabin is not required to be increased, the sound insulation capability of the mute cabin on low-frequency and/or medium-low frequency noise is improved, the sound insulation and noise reduction effects of the mute cabin are improved, and the user experience is improved.
In the control method for reducing the noise inside the mute cabin, a first noise propagated by a noise source is received by a reference microphone arranged on the outer wall of the mute cabin, and a second noise generated inside the mute cabin is received by an error microphone arranged on the inner wall of the mute cabin. The received noise signal is further transmitted to the noise active controller, and the noise active controller performs transfer function calculation based on the output white noise signal and the received second noise signal (i.e., the error signal), so that the cancellation effect of the secondary sound wave is improved under the condition that the sound propagation channel from the secondary sound source to the error microphone is accurately determined. And calculating, by the noise active controller, a secondary signal to be output to the secondary sound source based on the received first noise signal (i.e., the reference signal), the error signal, and the transfer function. Finally, the secondary signal is received by the secondary sound source, and the corresponding secondary sound wave is sent to the error microphone, so that the second noise can be offset in a sound silencing mode, and the sound insulation effect of the mute cabin is improved under the condition that the thickness of the wall of the mute cabin does not need to be increased.
Referring to fig. 5, in one embodiment, before receiving the first noise propagated by the noise source through the reference microphone, the method further comprises the steps of:
step S502, when the acoustic cavity is excited, confirming the acoustic wave frequency of the second noise generated currently through the acoustic testing instrument.
Step S502, according to the sound wave frequency, effective working frequency ranges of the reference microphone, the error microphone and the secondary sound source are confirmed respectively, so that the effective working frequencies of the reference microphone, the error microphone and the secondary sound source are ensured to contain the sound mode frequency.
The working frequency ranges of the secondary sound source, the error microphone and the reference microphone comprise the working frequency range of controlled noise, and the controlled noise represents the noise which is propagated to the interior of the mute cabin through the noise source.
It should be understood that although the steps in the flowcharts of fig. 2 and 5 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 2 and 5 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed in turn or alternately with other steps or at least some of the other steps.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware related to instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical storage, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above examples only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A control device for reducing the noise inside a mute compartment, said control device being applied to a mute compartment, there being a source of noise outside said mute compartment, the interior of said mute compartment comprising a sound cavity filled with air inside the cavity, characterized in that said device comprises a noise active controller, a secondary sound source, an error microphone and a reference microphone, wherein:
said noise active controller comprising a first input, a second input and an output, said error microphone being connected to said first input, said reference microphone being connected to said second input, said secondary sound source being connected to said output;
the reference microphone is arranged on the outer wall of the mute cabin, and the noise active controller, the error microphone and the secondary sound source are all arranged on the inner wall of the mute cabin and are not overlapped in position;
the reference microphone is used for receiving first noise propagated by the noise source and inputting the reference electric signal to the noise active controller when the first noise is converted into a reference electric signal;
the error microphone is used for receiving second noise transmitted by the sound cavity when the sound cavity is excited, and inputting the error electric signal to the noise active controller when the second noise is converted into an error electric signal;
the noise active controller is used for outputting a white noise signal to the secondary sound source and calculating to obtain a transfer function according to the white noise signal and the error signal; calculating to obtain a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function;
and the secondary sound source is used for receiving the secondary signal and sending corresponding secondary sound waves to the error microphone, and the secondary sound waves are used for offsetting the generated second noise.
2. The apparatus of claim 1, wherein the number of reference microphones is adapted to the number of noise sources;
the first installation positions of the reference microphones on the outer wall of the mute cabin respectively correspond to different first propagation directions, and the first propagation directions represent the directions of the noise source for propagating first noise.
3. The apparatus of claim 1, wherein the number of secondary sound sources and error microphones is adapted to the number of acoustic modes of the second noise generated corresponding to the acoustic cavity being excited;
a second mounting position of each error microphone on the inner wall of the mute cabin corresponds to a different second propagation direction, and the second propagation direction represents a direction in which the sound cavity is excited to correspondingly propagate second noise;
and the third mounting position of the secondary sound source on the inner wall of the mute cabin is matched with the second mounting position so as to ensure that when the sound cavity is excited, the first noise is counteracted through the secondary sound wave transmitted by the secondary sound source.
4. The apparatus of claim 3, wherein neither the second mounting location nor the third mounting location includes an acoustic modal node.
5. The apparatus of claim 1, wherein the operating frequency ranges of the secondary sound source, the error microphone, and the reference microphone each comprise an operating frequency range of controlled noise that characterizes noise propagating via the noise source to the interior of the mute compartment.
6. A control method for reducing noise inside a mute cabin, the method being applied to the control device according to any one of claims 1 to 5, comprising:
receiving a first noise propagated by the noise source through the reference microphone, and inputting a reference electric signal to the noise active controller when converting the first noise into the reference electric signal;
when the sound cavity is excited, receiving second noise transmitted by the sound cavity through the error microphone, and when the second noise is converted into an error electric signal, inputting the error electric signal to the noise active controller;
outputting a white noise signal to the secondary sound source through the noise active controller, and calculating to obtain a transfer function according to the white noise signal and an error signal; calculating to obtain a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function;
and receiving the secondary signal by the secondary sound source, and sending a corresponding secondary sound wave to the error microphone, wherein the secondary sound wave is used for offsetting the generated second noise.
7. The method of claim 6, wherein prior to receiving the first noise propagated by the noise source by the reference microphone, the method further comprises:
confirming the number of noise sources arranged outside the mute cabin and the direction of the noise sources for transmitting the first noise;
when the acoustic cavity is excited, confirming the number of the acoustic modes of the second noise generated currently and the direction of the second noise by an acoustic testing instrument;
determining the number of the reference microphones according to the number of the noise sources, and determining the number of the secondary sound sources and the number of the error microphones according to the number of the sound modes of the second noise generated currently;
determining a first mounting position of each reference microphone on the outer wall of the mute cabin according to the direction of the first noise transmitted by the noise source;
and determining a second mounting position of each error microphone on the inner wall of the mute cabin according to the propagation direction of the second noise and the shape of the acoustic mode, and determining a third mounting position of each secondary sound source on the inner wall of the mute cabin according to the determined second mounting position.
8. The method of claim 6, wherein prior to receiving the first noise propagated by the noise source by the reference microphone, the method further comprises:
confirming the sound wave frequency of the second noise generated currently by an acoustic testing instrument when the sound cavity is excited;
and respectively confirming effective working frequency ranges of the reference microphone, the error microphone and the secondary sound source according to the sound wave frequency so as to ensure that the effective working frequencies of the reference microphone, the error microphone and the secondary sound source comprise the sound mode frequency.
9. The method of claim 6, wherein calculating a transfer function from the white noise signal and the error signal comprises:
Figure FDA0002980394810000031
wherein the content of the first and second substances,
Figure FDA0002980394810000032
refers to the transfer function, e (Z) refers to the error signal, and x (Z) refers to the white noise signal.
10. The method of claim 6, wherein calculating a secondary signal to be output to the secondary sound source according to the reference signal, the error signal and the transfer function comprises:
y(n)＝xin(n)*w(n)；
Figure FDA0002980394810000033
wherein y (n) denotes a secondary signal, xin(n) refers to the reference signal, w (n) refers to the first adaptive filter coefficients of the noise active controller; mu refers to an iteration coefficient, w (n +1) refers to a second adaptive filter coefficient corresponding to the current noise active controller when the next iteration is started; e (n) refers to the error signal,
Figure FDA0002980394810000034
refers to the impulse response corresponding to the transfer function.
CN202110285773.9A 2021-03-17 2021-03-17 Control device and method for reducing noise inside mute cabin Pending CN112885324A (en)

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