CN108088064B - Active noise reduction device arranged on ventilation pipe orifice and capable of realizing acoustic interaction and control method - Google Patents

Active noise reduction device arranged on ventilation pipe orifice and capable of realizing acoustic interaction and control method Download PDF

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CN108088064B
CN108088064B CN201810036999.3A CN201810036999A CN108088064B CN 108088064 B CN108088064 B CN 108088064B CN 201810036999 A CN201810036999 A CN 201810036999A CN 108088064 B CN108088064 B CN 108088064B
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noise reduction
noise
loudspeaker
input
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CN108088064A (en
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安峰岩
刘碧龙
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Qingdao University of Technology
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/24—Means for preventing or suppressing noise
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/24—Means for preventing or suppressing noise
    • F24F2013/247—Active noise-suppression
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

The invention relates to an active noise reduction device which is arranged at a ventilation pipe orifice and can realize acoustic interaction, comprising a shell, a loudspeaker, a reference microphone, a plurality of error microphones, a controller and a diffuser; the loudspeaker is arranged in the shell; the reference microphone is arranged at the top of the shell, and the acoustic input end of the reference microphone faces the outside of the shell; each error microphone is arranged on the bottom surface of the shell and is arranged at a position close to the edge of the bottom surface; the controller is arranged in the shell, and the loudspeaker, the reference microphone and the error microphones are all connected to the controller through leads; a third through hole is formed in the center of the diffuser, and the bottom surface of the shell is arranged in the third through hole. The invention further provides an active noise reduction control method capable of realizing acoustic interaction. The invention has simple structure and small volume, and can realize acoustic interaction through the active noise reduction device while actively reducing noise.

Description

Active noise reduction device arranged on ventilation pipe orifice and capable of realizing acoustic interaction and control method
Technical Field
The invention relates to the technical field of noise control, in particular to an active noise reduction device which is arranged at a ventilation pipe orifice and can realize acoustic interaction and a control method.
Background
With the progress of modern society and the improvement of living standard of people, the problem of noise pollution is increasingly prominent, and the daily life of people is seriously affected. Along with the wide application of noise control technology, noise from air inlets and outlets of a central air conditioner and a fresh air system has become one of the main noise sources in indoor environments. The noise low-frequency component is prominent, and effective suppression by a passive noise reduction means is difficult in a limited space.
The active noise control is a noise active control technology based on the acoustic wave coherent superposition principle, and the basic principle is that a secondary sound source is introduced into a sound field, and the secondary sound source is utilized to emit 'anti-noise' with the same amplitude as the original noise but opposite phase, so that the original noise is coherently counteracted, and the purpose of noise suppression is achieved. The active noise control technique is small in size and light in weight, and has remarkable advantages in controlling low-frequency noise. The invention patent with publication number of CN104165255B discloses an active and passive composite muffler for a ventilation pipeline, which is mainly used for optimally designing a high-wind-speed ventilation pipeline (such as a ship), has a complex structure and a large volume, and is difficult to be used for pipelines such as a central air conditioner and a fresh air system in daily indoor environments. Meanwhile, the loudspeaker and the microphone in the technical scheme are arranged in the pipeline, so that only noise reduction can be realized, and the acoustic interaction function is not realized.
With the popularization of devices such as intelligent sound equipment and the wide application of voice interaction, the requirement of an acoustic interaction function is increasingly urgent. In order to suppress low frequency noise, the active noise control system must be provided with acoustic input and output devices (e.g. microphones and loudspeakers) that pick up the acoustic signals of the target area (e.g. speech uttered by a person) and emit sound (e.g. music) in the target area, which provides the necessary conditions for simultaneously implementing the acoustic interaction function. However, the interference between active noise reduction and acoustic interaction forms: the microphone of the active noise reduction system is generally placed at a position with more obvious low-frequency noise, which causes larger interference to the acoustic signals such as voice of the extraction target area; in addition, when the loudspeaker of the active noise reduction system is directly used for playing sound signals such as music, the self-adaptive noise reduction algorithm is strongly interfered, and the normal operation of the system is seriously influenced. How to combine active noise reduction with acoustic interaction organically, there is still no effective method at present.
Disclosure of Invention
In order to solve the technical problems, the invention provides an active noise reduction device which is arranged at a ventilation pipe orifice and can realize acoustic interaction and a control method thereof, which can realize active noise reduction and acoustic interaction.
The technical scheme is as follows:
the active noise reduction device is arranged at the vent pipe orifice and can realize acoustic interaction and comprises a shell, a loudspeaker, a reference microphone, a plurality of error microphones, a controller and a diffuser; a first through hole is formed in the bottom surface of the shell, and a second through hole is formed in the top of the shell; the loudspeaker is arranged in the shell, the cone of the loudspeaker faces outwards and is arranged on the first through hole, and the inner space enclosed by the shell and the loudspeaker forms a rear cavity of the loudspeaker; the reference microphone is arranged on the second through hole, and the acoustic input end of the reference microphone faces the outside of the shell; each error microphone is arranged on the bottom surface of the shell and at a position close to the edge of the bottom surface, and the acoustic input end of each error microphone faces to the outside of the shell; the controller is arranged in the shell, and the loudspeaker, the reference microphone and the error microphones are all connected to the controller through leads; the center position of the diffuser is provided with a third through hole, the bottom surface of the shell is arranged in the third through hole, when the diffuser is installed at the ventilation pipe orifice, one side of the shell, which is provided with the reference microphone, is used as the inner side and is arranged in the ventilation pipe orifice, the bottom surface of the shell is used as the outer side and is arranged at the ventilation pipe orifice, and the loudspeaker directly sounds indoors.
More preferably, the controller includes a wireless communication module, and an a/D converter, a digital signal processor, a D/a converter and a power amplifier that connect in order, and the external sound control device carries out two-way communication with the digital signal processor through the wireless communication module, the a/D converter gathers the output signal of reference microphone and each error microphone, the D/a converter will need the signal output that the speaker broadcast to the power amplifier, the power amplifier connects the speaker.
More preferably, the active noise reduction device further comprises a sound absorption material layer, wherein the sound absorption material layer is arranged on the outer surface of the shell except for the bottom surface of the shell, and comprises the outer side of the reference microphone, and the sound absorption material layer is used for increasing the passive noise reduction effect and reducing the wind noise of the reference microphone.
More preferably, the shell is a conical shell, the second through hole is formed in the top of the conical shell, the reference microphone is mounted on the second through hole in a sealing mode, and the sealing connection mode comprises gluing or adding a soft cushion.
The second technical scheme is as follows:
the active noise reduction control method capable of acoustic interaction comprises the steps that the reference microphone picks up an acoustic signal in a ventilation pipeline, wherein the acoustic signal comprises an original noise signal in the pipeline, an inverted noise signal emitted by a loudspeaker and an audio signal input by external sound control equipment played by the loudspeaker; the acoustic signal picked up by the error microphone comprises: the device comprises a residual noise signal formed by superposition of an original noise signal transmitted from the inside of a pipeline and an inverted noise signal sent by a loudspeaker, an audio signal input by external sound control equipment played by the loudspeaker and control voice sent by a person; the digital signal processor is internally provided with a software module which is operated simultaneously and is used for processing acoustic signals, and the software module comprises a noise reduction module, an echo cancellation module and a noise reduction enhancement module; in the process of processing noise reduction and acoustic interaction, the noise reduction module, the echo cancellation module and the noise reduction enhancement module operate simultaneously and are not sequenced;
the control method specifically comprises the following steps:
and the noise reduction module is used for inhibiting low-frequency radiation noise generated in the ventilating duct: the noise reduction module comprises a noise reduction filter, an acoustic feedback channel model, a secondary channel model and a filter updating algorithm module; the noise reduction filter filters original noise in the pipeline and outputs inverted noise with the same amplitude as the original noise but opposite phase, the inverted noise is overlapped with an audio signal input by the external sound control equipment and then is used as an output signal of the noise reduction module to drive the loudspeaker, and the inverted noise is also used as an input of the acoustic feedback channel model; the output signal of the noise reduction module is filtered by the acoustic feedback channel model and then is inverted, and is overlapped with the acoustic signal picked up by the reference microphone, after the superposition, the inverse noise signal picked up by the reference microphone and sent by the loudspeaker and the audio signal input by the external sound control equipment played by the loudspeaker are eliminated, only the original noise in the pipeline is left, the original noise is used as the input of the noise reduction filter, meanwhile, the original noise is also used as the input of the secondary channel model, and the original noise is used as the input of the filter updating algorithm module after being filtered by the secondary channel model;
the echo cancellation module is used for acquiring control voice sent by a person: the echo cancellation module comprises a plurality of sub-modules, the sub-modules are arranged in one-to-one correspondence with the error microphones, and each sub-module comprises an echo cancellation filter and an adaptive algorithm module; the input of the echo cancellation filter is an audio signal input by external sound control equipment, the audio signal is filtered and inverted, and then the audio signal is overlapped with an acoustic signal picked up by the error microphone, the overlapped signal is used as an output signal of the sub-module, the output signal of the sub-module removes the audio signal input by the external sound control equipment played by the loudspeaker, but the audio signal comprises control voice of a person, the output signal of the sub-module is sent to the external sound control equipment through the wireless communication module, and the acoustic interaction is realized by combining the audio signal input by the external sound control equipment through the wireless communication module; meanwhile, the output signals of the submodules are also used as the input of the self-adaptive algorithm module and the input of the filter updating algorithm module, the input of the self-adaptive algorithm module also comprises an audio signal input by external sound control equipment, the self-adaptive algorithm module outputs parameters for updating the echo cancellation filter, and the self-adaptive algorithm module carries out self-adaptive adjustment on the parameters of the echo cancellation filter according to the audio signal input by the external sound control equipment and the output signals of the submodules, so as to better eliminate the audio signal input by the external sound control equipment, which is played by the loudspeaker and picked up by an error microphone;
the input of the filter updating algorithm module comprises the superposition of the output signals of the secondary channel model and the output signals of the echo cancellation sub-modules, and the output of the filter updating algorithm module is used for adaptively adjusting the coefficient of the noise reduction filter, so that the filter updating algorithm module aims at better inhibiting the residual noise signals picked up by the error microphone, and further better active noise reduction effect is achieved.
The input of the noise reduction enhancement module is the parameter of each echo cancellation filter, and the noise reduction enhancement module overlaps the parameter of each echo cancellation filter and performs time domain smoothing, and the result is used as a new parameter of the secondary channel model to realize the real-time update of the secondary channel model.
More preferably, the noise reduction filter, the acoustic feedback channel model, the secondary channel model, and the echo cancellation filter all employ FIR filters, wherein the secondary channel model and the echo cancellation filter have the same order.
The invention has the following beneficial effects:
(1) The active noise reduction device provided by the invention does not need to modify the original pipeline system, has small volume and convenient use, and can effectively inhibit low-frequency noise radiated from the ventilation pipe orifice to the room;
(2) According to the active noise reduction device provided by the invention, the noise in the ventilating duct is picked up by the reference sensor, and the anti-phase noise is played by the loudspeaker, so that the noise in the duct and the anti-phase noise are mutually counteracted, and the low-frequency noise radiated to the room by the ventilating duct orifice is effectively inhibited;
(3) According to the active noise reduction device provided by the invention, the voice of a person is picked up through the error microphone, and the externally input audio signal is played through the loudspeaker, so that acoustic interaction is realized;
(4) The active noise reduction control method provided by the invention has the functions of sound reproduction and array sound perception, and the active noise control and the acoustic interaction function are organically combined and mutually promoted, so that the active noise control and the acoustic interaction function have better performance than the active noise control and the array sound perception function when independently working.
Drawings
FIG. 1 is a schematic diagram of an active noise reduction device according to the present invention;
FIG. 2 is a front view of an active noise reduction device of the present invention;
FIG. 3 is a schematic diagram of a controller in an active noise reduction device of the present invention;
FIG. 4 is a system block diagram of an active noise reduction control method of the present invention;
fig. 5 is a flow chart of the active noise reduction control method of the present invention.
The reference numerals in the drawings are as follows:
1. a housing; 11. a first through hole; 12. a second through hole; 2. a speaker; 21. a cone; 3. a reference microphone; 4. an error microphone; 5. a controller; 51. a wireless communication module; 52. an A/D converter; 53. a digital signal processor; 54. a D/A converter; 55. a power amplifier; 6. a diffuser; 61. A third through hole; 7. an external sound control device; 8. a layer of sound absorbing material; 100. A noise reduction module; 101. A noise reduction filter; 102. an acoustic feedback channel model; 103. a secondary channel model; 104. a filter updating algorithm module; 200. an echo cancellation module; 201. an echo cancellation filter; 202. an adaptive algorithm module; 300. and the noise reduction enhancing module.
Detailed Description
The invention will be described in detail below with reference to fig. 1 to 5 of the accompanying drawings and specific embodiments.
Embodiment one:
referring to fig. 1 and 2, an active noise reduction device disposed at a vent pipe orifice and capable of acoustic interaction includes a housing 1, a speaker 2, a reference microphone 3, a plurality of error microphones 4 (four are shown in fig. 1 to 3), a controller 5, and a diffuser 6; a first through hole 11 is formed in the bottom surface of the shell 1, and a second through hole 12 is formed in the top of the shell 1; the loudspeaker 2 is arranged in the shell 1, the cone 21 of the loudspeaker is outwards arranged on the first through hole 11, and the inner space enclosed by the shell 1 and the loudspeaker 2 forms a rear cavity of the loudspeaker 2; the reference microphone 3 is provided on the second through hole 12 and an acoustic input end of the reference microphone 3 faces the outside of the case 1; each error microphone 4 is disposed on the bottom surface of the housing 1 and at a position close to the edge of the bottom surface, and the acoustic input end of each error microphone 4 faces to the outside of the housing 1, that is, the noise outside the housing 1 is measured by the reference microphone 3; the controller 5 is arranged in the shell 1, and the loudspeaker 2, the reference microphone 3 and the error microphones 4 are all connected to the controller 5 through leads; the center of the diffuser 6 is provided with a third through hole 61, the bottom surface of the housing 1 is disposed in the third through hole 61, when the diffuser 6 is mounted on a ventilation pipe orifice, one side of the housing 1 provided with the reference microphone 3 is disposed as the inner side, the inner side of the ventilation pipe orifice is disposed to pick up an acoustic signal in a ventilation pipe, the bottom surface of the housing 1 is disposed as the outer side, and the ventilation pipe orifice is disposed to make the speaker 2 directly sound indoors, and meanwhile, the bottom surface error microphone 4 is utilized to pick up an indoor acoustic signal. In the embodiment, the whole diffuser is rectangular, and the bottom surface of the shell 1 is correspondingly arranged at a rectangular ventilation pipe orifice; in other embodiments, the bottom surface of the housing 1 and the grille may be circular, and the diffuser is circular as a whole and is correspondingly disposed at the circular ventilation pipe opening.
The various components of the active noise reduction device of the present invention are further described below.
In this embodiment, as shown in fig. 1, the active noise reduction device further includes a sound absorption material layer 8, and the outer surface of the housing 1 is provided with the sound absorption material layer 8 except for the bottom surface of the housing 1, including the outer side of the reference microphone 3, where the sound absorption material layer 8 is used to increase the passive noise reduction effect and reduce the wind noise of the reference microphone 3.
The casing 1 is the toper casing, the second through-hole 12 open and is located the top of toper casing, the reference microphone 3 install in on the second through-hole 12, the advantage of selecting for use the toper casing is: the wind resistance is low, and no noise is additionally generated.
The joint of the reference microphone 3 and the second through hole 12 is in sealing connection, and the sealing connection mode comprises gluing or adding a soft cushion.
Referring to fig. 3, the controller 5 includes a wireless communication module 51, and an a/D converter 52, a digital signal processor 53, a D/a converter 54 and a power amplifier 55 connected in sequence, the external voice control device 7 communicates with the digital signal processor 53 in two directions through the wireless communication module 51, the a/D converter 52 collects output signals of the reference microphone 3 and each error microphone 4, the D/a converter 54 outputs a signal to be played by the speaker 2 to the power amplifier 55, and the power amplifier 55 is connected to the speaker 2.
The working principle of the invention is as follows: the active noise reduction device is arranged at the ventilation pipe opening, the reference microphone 3 is positioned in the ventilation pipeline, and the picked-up sound signal comprises: the original noise signal inside the pipeline, the inverted noise signal emitted by the loudspeaker 2 and the audio signal input by the external sound control device 7 played by the loudspeaker 2, wherein the inverted noise signal is noise which is processed by the digital signal processor 53 and is the same as the original noise in amplitude but opposite in phase, and the inverted noise and the original noise are mutually counteracted outside the pipe orifice, so that the low-frequency noise radiated from the ventilation pipe orifice into the room is greatly attenuated, and active noise reduction is realized. The error microphone 4 is located at the vent pipe mouth, and the picked-up acoustic signals include: the residual noise signal formed by superposition of the original noise signal propagated from the inside of the pipeline and the inverted noise signal emitted from the loudspeaker (2), the audio signal input by the external sound control device 7 played by the loudspeaker (2) and the control voice emitted by the person. The active noise reduction can greatly attenuate the residual noise signal, and the audio signal input by the external voice control device 7 can be processed and eliminated by the digital signal processor 53, so that pure control voice is obtained, and the control voice is transmitted to the external voice control device 7 by the wireless communication module 51; meanwhile, the audio input of the external sound control device 7 is sent to the digital signal processor 53 through the wireless communication module 51, and the audio is processed by the digital signal processor 53 and then is sent to the loudspeaker 2 through the power amplifier 55, so that the acoustic interaction function with the external sound control device 7 is realized.
Embodiment two:
referring to fig. 4 and 5, in combination with the active noise reduction device according to the first embodiment, the reference microphone 3 picks up an acoustic signal in a ventilation duct, which includes an original noise signal in the duct, an inverted noise signal emitted by the speaker 2, and an audio signal input by an external sound control device 7 played by the speaker 2; the acoustic signals picked up by the error microphone 4 include: a residual noise signal formed by superposition of an original noise signal propagated from the inside of the pipeline and an inverted noise signal emitted by the loudspeaker 2, an audio signal input by an external sound control device 7 played by the loudspeaker 2, and a control voice emitted by a person; the digital signal processor 53 is provided with software modules for processing acoustic signals, including a noise reduction module 100, an echo cancellation module 200 and a noise reduction enhancement module 300; the three are operated simultaneously and are not in sequence;
the control method specifically comprises the following steps:
low frequency radiation noise generated in the ventilation duct is suppressed by the noise reduction module 100, specifically: the noise reduction module 100 comprises a noise reduction filter 101, an acoustic feedback channel model 102, a secondary channel model 103 and a filter update algorithm module 104; the noise reduction filter 101 filters original noise inside a pipeline and outputs inverted noise with the same amplitude but opposite phase to the original noise, the inverted noise is overlapped with an audio signal input by the external sound control device 7 and then is used as an output signal of the noise reduction module 100 to drive the loudspeaker 2, and meanwhile, the output signal of the noise reduction module 100 is also used as an input of the acoustic feedback channel model 102; the output signal of the noise reduction module 100 is filtered by the acoustic feedback channel model 102 and then is inverted, and is overlapped with the acoustic signal picked up by the reference microphone 3, after the superposition, the inverted noise signal picked up by the reference microphone 3 and sent by the loudspeaker 2 and the audio signal input by the external sound control equipment 7 played by the loudspeaker 2 are eliminated, only the original noise in the pipeline is left, the original noise is used as the input of the noise reduction filter 101, meanwhile, the original noise is also used as the input of the secondary channel model 103, and the original noise is filtered by the secondary channel model 103 and then is used as the input of the filter updating algorithm module 104;
the echo cancellation module 200 acquires control voice sent by a person, specifically: the echo cancellation module 200 comprises a plurality of sub-modules, the sub-modules are arranged in one-to-one correspondence with the error microphone 4, and each sub-module comprises an echo cancellation filter 201 and an adaptive algorithm module 202; the input of the echo cancellation filter 201 is an audio signal input by the external sound control device 7, the audio signal is filtered and inverted, and then the audio signal is overlapped with an acoustic signal picked up by the error microphone 4, the overlapped signal is used as an output signal of the sub-module, the output signal of the sub-module removes the audio signal input by the external sound control device 7 played by the loudspeaker 2, but includes control voice of a person, the output signal of the sub-module is sent to the external sound control device 7 through the wireless communication module 51, and acoustic interaction is realized by combining the audio signal input by the external sound control device 7 through the wireless communication module 51.
Meanwhile, the output signals of the sub-modules are also used as the input of the adaptive algorithm module 202 and the input of the filter updating algorithm module 104, the input of the adaptive algorithm module 202 also comprises the audio signal input by the external sound control device 7, and the adaptive algorithm module 202 outputs the parameters for updating the echo cancellation filter 201.
The adaptive algorithm module 202 adaptively adjusts parameters of the echo cancellation filter 201 according to the audio signal input by the external voice control device 7 and the output signal of the submodule, so as to better eliminate the audio signal input by the external voice control device 7 played by the speaker 2 and picked up by the error microphone 4;
the input of the filter updating algorithm module 104 includes the superposition of the output signal of the secondary channel model 103 and the output signal of each echo cancellation sub-module, and the output of the filter updating algorithm module 104 is used for adaptively adjusting the coefficient of the noise reduction filter 101, so as to better suppress the residual noise signal picked up by the error microphone 4, thereby realizing better active noise reduction effect.
The algorithms adopted by the filter updating algorithm module 104 and the adaptive algorithm module comprise LMS, RLS, AP and other general adaptive algorithms.
In this embodiment, the noise reduction filter 101, the acoustic feedback channel model 102, the secondary channel model 103, and the echo cancellation filter 201 all use FIR filters, where the secondary channel model 103 and the echo cancellation filter 201 have the same order.
The input of the noise reduction enhancement module 300 is the parameters of each echo cancellation filter 201, and the noise reduction enhancement module 300 superimposes and time-domain smoothes the parameters of each echo cancellation filter 201, and then the result is used as a new parameter of the secondary channel model 103 to realize real-time update of the secondary channel model 103.
In the application scenario of the active noise reduction control method of the present invention, in the initial operation stage of the noise reduction module 100, the noise reduction module 100 does not operate stably, and the acoustic signal picked up by the error microphone 4 is composed of three parts: firstly, low-frequency noise radiated from the opening of the ventilating duct into the room, secondly, an audio signal (such as music) input by an external sound control device 7 played by the loudspeaker 2, and thirdly, control voice emitted by a person. The three acoustic signal components interfere with each other, thereby affecting the functional effect of the different acoustic processing modules.
First, after the noise reduction module 100 stably operates, the low-frequency noise component radiated from the pipe orifice into the room is greatly suppressed, and the low-frequency noise radiated from the ventilation pipe orifice into the room picked up by the error microphone 4 is attenuated to a greater extent. The basic principle of the noise reduction module 100 is as follows: the original noise signal inside the duct is picked up by the reference microphone 3, filtered by the noise reduction filter 101 and the speaker 2 is driven to emit the opposite phase noise having the same amplitude as the original noise but opposite phase, which is cancelled with the original noise, thereby greatly attenuating the low frequency noise radiated from the ventilation pipe opening into the room. But in actual operation the signal picked up by the reference microphone 3 mainly comprises four parts: the original noise signal inside the pipeline, the anti-phase noise emitted by the loudspeaker 2, the audio signal (such as music) input by the external sound control equipment 7 played by the loudspeaker 2, and the control voice emitted by the person. Since the reference microphone 3 is placed inside the canal, the upper fourth part has a weak signal, the influence of which is negligible; however, the second and third portions will form a feedback loop, severely interfering with the proper operation of the noise reduction module 100. To eliminate this feedback loop, an acoustic transfer function model between the loudspeaker 2 and the reference microphone 3 is built using the acoustic feedback channel model 102, so that the second, third part signal is predicted and eliminated from the reference signal.
The signal driving the loudspeaker 2 comprises a superposition of two parts: firstly, the output of the noise reduction filter 101 drives the loudspeaker 2 to emit inverse noise so as to complete the active noise reduction function; and secondly, the audio signal input by the external sound control device 7 drives the loudspeaker 2 to complete sound reproduction, i.e. sound such as music expected by a user is emitted.
After the noise reduction module 100 works stably, the inverse noise emitted by the loudspeaker 2 and the original noise of the ventilation pipeline are mutually counteracted, so that the first part of noise energy picked up by the error microphone 4 is greatly attenuated. However, since the speaker 2 is located close to the error microphone 4, the audio signal (i.e., the sound desired by the user) input from the external voice control device 7, which is played by the speaker 2, is more energetic, and will cause a strong disturbance to other sound signal components in the room. The function of the echo cancellation module 200 is to remove this interference, and the signal-to-noise ratio of other indoor acoustic signal components in the output signal of the module will be greatly improved.
Secondly, when the noise reduction module 100 does not enter a stable working state, the output signals of the echo cancellation sub-modules still have stronger pipe orifice low-frequency radiation noise components. Therefore, after the output signals of all the echo cancellation submodules are overlapped, the output signals are input into the noise reduction module 100, and the filter updating algorithm module 104 adjusts parameters of the noise reduction filter 101 according to low-frequency noise energy in the overlapped signals, so that the noise reduction module 100 enters a stable working state. The other input of the filter update algorithm module 104 is the in-tube raw noise signal filtered by the secondary channel model 103, and an acoustic transfer function model of the sum of the picked-up signals of the loudspeaker 2 to all error microphones 4 is built up by using the secondary channel model 103. The filter update algorithm module 104 may employ a general adaptive algorithm such as LMS, RLS, AP.
In the field of active noise control, the secondary channel model 103 refers to the transfer function between the loudspeaker 2 and the error microphone 4, which in the present invention refers to the transfer function of the sum of the loudspeaker 2 to all error microphone 4 signals. As described above, the noise reduction module 100 needs to utilize the model of this transfer function to perform the adaptive adjustment function of the parameters of the noise reduction filter 101. In practice, the frequency response of the secondary channel is often time-varying, subject to obstructions, moving objects in the room, and fatigue characteristics of the speaker 2. This will cause a discrepancy between the secondary channel model 103 and the actual response, thereby affecting the noise reduction effect and even the stability of the overall module. While the echo cancellation module 200 exactly contains an effective estimate of the time-varying secondary channel model 103, the echo cancellation module 200 and the noise reduction module 100 are organically combined using a noise reduction enhancement module.
The specific implementation process is now given in combination with specific algorithms:
the signals are represented as follows: reference microphone signal
Figure SMS_1
I-th error microphone signal +.>
Figure SMS_5
External sound source input signal->
Figure SMS_7
Noise reduction filter output signal->
Figure SMS_3
Noise reduction module outputs signal +.>
Figure SMS_4
Output signal of acoustic feedback channel model
Figure SMS_6
Secondary channel model output signal->
Figure SMS_8
Echo cancellation submodule output signal corresponding to ith error microphone
Figure SMS_2
。
Noise reduction module 100:
the noise reduction filter 101 is an N-order FIR filter with coefficients of
Figure SMS_9
The filter inputs and outputs are respectively:
Figure SMS_10
，
Figure SMS_11
；
the output of the noise reduction module 100 is
Figure SMS_12
And->
Figure SMS_13
Is superimposed on the (d): />
Figure SMS_14
This signal drives the speaker 2 to sound through the power amplifier 55;
at the same time, the method comprises the steps of,
Figure SMS_15
also as input signal to the acoustic feedback channel model 102, an output +.>
Figure SMS_16
The method comprises the steps of carrying out a first treatment on the surface of the The acoustic feedback path model 102 is a K-order FIR filter with filter coefficients +.>
Figure SMS_17
The input-output relationship is as follows:
Figure SMS_18
；
the secondary channel model 103 is an L-order FIR filter with filter coefficients
Figure SMS_19
The input-output relationship is:
Figure SMS_20
；
all are put together
Figure SMS_21
Superimposed to get->
Figure SMS_22
Utilize->
Figure SMS_23
And->
Figure SMS_24
Adaptively updating the coefficients of the noise reduction filter 101 according to an LMS algorithm: />
Figure SMS_25
，
Figure SMS_26
，
In the middle of
Figure SMS_27
Is a constant and typically takes a value of 0.1.
Initializing: before the algorithm is executed,
Figure SMS_28
set 0->
Figure SMS_29
And->
Figure SMS_30
It is obtained by an off-line system identification method in which the acoustic feedback path model 102 is the transfer function between the input signal of the power amplifier 55 and the output signal of the reference microphone 3, and the secondary path model 103 is the transfer function between the input signal of the power amplifier 55 and the output superimposed signal of all error microphones 4.
Echo cancellation module 200:
the echo cancellation filter 201 corresponding to the ith echo cancellation sub-module is an L-order FIR filter with filter coefficients
Figure SMS_31
Input->
Figure SMS_32
And output->
Figure SMS_33
The relation of (2) is:
Figure SMS_34
；
the output of the echo cancellation sub-module is:
Figure SMS_35
；
pair of using LMS algorithm
Figure SMS_36
Updating:
Figure SMS_37
，
in the middle of
Figure SMS_38
Is a constant and typically takes a value of 0.1.
Initializing: before the algorithm is executed,
Figure SMS_39
set to 0.
Noise reduction enhancement module 300:
all the echo cancellation filter 201 coefficients
Figure SMS_40
Adding, processing with time domain smoothing algorithm, and obtaining result +.>
Figure SMS_41
Updating:
Figure SMS_42
，
in the middle of
Figure SMS_43
Is a constant and typically takes a value of 0.01.
The invention provides an active noise reduction control method capable of acoustic interaction, which has an acoustic replay function, wherein a user provides a sound source input signal by using an external sound control device 7 and plays audio expected to be heard by the user through a loudspeaker 2; and an array sound sensing function, namely forming an array through a plurality of error sensors, sensing control voice sent by a person and sending the control voice to an external sound control device 7; and simultaneously, the active noise control and the echo cancellation control are organically combined. The active noise control adopts a feedforward structure and an algorithm, and can inhibit the noise of a ventilation pipeline at the position of the error microphone 4, so that the array formed by the error microphone 4 is less interfered by low-frequency noise when picking up indoor acoustic signals (namely control voice sent by a person); meanwhile, under the condition that the sound source of the external sound control equipment 7 is input for indoor sound replay, the parameters of the secondary channel model 103 are dynamically and real-timely adjusted by utilizing the intermediate parameters of the self-adaptive algorithm of echo cancellation, so that the real-time update of the physical channel model between the loudspeaker 2 and the error microphone 4 is realized, and the stability and the noise reduction effect of the active noise reduction system are improved. In addition, because the ventilation pipe orifice is generally positioned at the middle part of the indoor ceiling, the array formed by the error microphones 4 is less affected by sound reflection and scattering caused by indoor furniture and moving objects, the accuracy of acoustic signal pickup is improved, and the comfort of acoustic interaction products is improved.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present invention.

Claims (3)

1. Locate the active noise reduction device that ventilates the mouth of pipe and can acoustic interaction, its characterized in that: comprises a shell (1), a loudspeaker (2), a reference microphone (3), a plurality of error microphones (4), a controller (5) and a diffuser (6); a first through hole (11) is formed in the bottom surface of the shell (1), and a second through hole (12) is formed in the top of the shell (1); the loudspeaker (2) is arranged in the shell (1), the cone (21) of the loudspeaker is outwards arranged on the first through hole (11), and the inner space enclosed by the shell (1) and the loudspeaker (2) forms a rear cavity of the loudspeaker (2); the reference microphone (3) is arranged on the second through hole (12) and the acoustic input end of the reference microphone (3) faces the outside of the shell (1); each error microphone (4) is arranged on the bottom surface of the shell (1) and is arranged at a position close to the edge of the bottom surface, and the acoustic input end of each error microphone (4) faces the outside of the shell (1); the controller (5) is arranged in the shell (1), and the loudspeaker (2), the reference microphone (3) and the error microphones (4) are all connected to the controller (5) through leads; a third through hole (61) is formed in the center of the diffuser (6), the bottom surface of the shell (1) is arranged in the third through hole (61), when the diffuser (6) is installed on a ventilation pipe orifice, one side of the shell (1) provided with the reference microphone (3) is used as the inner side and is arranged in the ventilation pipe orifice, the bottom surface of the shell (1) is used as the outer side and is arranged in the ventilation pipe orifice, and the loudspeaker (2) directly sounds indoors; the controller (5) comprises a wireless communication module (51), and an A/D converter (52), a digital signal processor (53), a D/A converter (54) and a power amplifier (55) which are sequentially connected, wherein an external sound control device (7) is in bidirectional communication with the digital signal processor (53) through the wireless communication module (51), the A/D converter (52) collects output signals of the reference microphone (3) and each error microphone (4), the D/A converter (54) outputs signals required to be played by a loudspeaker (2) to the power amplifier (55), and the power amplifier (55) is connected with the loudspeaker (2); the sound absorption device further comprises a sound absorption material layer (8), wherein the sound absorption material layer (8) is arranged on the outer surface of the shell (1) except the bottom surface of the shell (1), the sound absorption material layer (8) comprises the outer side of the reference microphone (3), and the sound absorption material layer (8) is used for increasing the passive noise reduction effect and reducing the wind noise of the reference microphone (3); the shell (1) is a conical shell, the second through hole (12) is formed in the top of the conical shell, and the reference microphone (3) is mounted on the second through hole (12) in a sealing mode.
2. An active noise reduction control method capable of acoustic interaction, characterized in that it combines the active noise reduction device of claim 1, the reference microphone (3) picks up an acoustic signal in the ventilation duct, which comprises an original noise signal inside the duct, an inverted noise signal emitted by the speaker (2) and an audio signal input by an external sound control device (7) played by the speaker (2); the acoustic signal picked up by the error microphone (4) comprises: the device comprises a residual noise signal formed by superposition of an original noise signal transmitted from the inside of a pipeline and an inverted noise signal emitted by a loudspeaker (2), an audio signal input by an external sound control device (7) played by the loudspeaker (2) and control voice emitted by a person; the digital signal processor (53) is internally provided with a software module which is operated simultaneously and is used for processing acoustic signals, and the software module comprises a noise reduction module (100), an echo cancellation module (200) and a noise reduction enhancement module (300), wherein the noise reduction module (100), the echo cancellation module (200) and the noise reduction enhancement module (300) are operated simultaneously in the process of processing noise reduction and acoustic interaction, and the noise reduction are not sequential;
the control method specifically comprises the following steps:
-suppressing, by the noise reduction module (100), low frequency radiation noise generated in the ventilation duct: the noise reduction module (100) comprises a noise reduction filter (101), an acoustic feedback channel model (102), a secondary channel model (103) and a filter updating algorithm module (104); the noise reduction filter (101) filters original noise in a pipeline and outputs inverted noise with the same amplitude as the original noise but opposite phase, and the inverted noise is overlapped with an audio signal input by the external sound control equipment (7) and then is used as an output signal of the noise reduction module (100) to drive the loudspeaker (2) and is also used as an input of the acoustic feedback channel model (102); the output signal of the noise reduction module (100) is filtered by the acoustic feedback channel model (102) and then is inverted, the inverted noise signal which is picked up by the reference microphone (3) and is sent by the loudspeaker (2) and the audio signal which is input by the external sound control equipment (7) and is played by the loudspeaker (2) are eliminated after being overlapped, only original noise in a pipeline is left, the original noise is used as the input of the noise reduction filter (101), meanwhile, the original noise is also used as the input of the secondary channel model (103), and the original noise is filtered by the secondary channel model (103) and is used as the input of the filter updating algorithm module (104);
the echo cancellation module (200) is used for acquiring control voice sent by a person: the echo cancellation module (200) comprises a plurality of sub-modules, the sub-modules are arranged in one-to-one correspondence with the error microphone (4), and each sub-module comprises an echo cancellation filter (201) and an adaptive algorithm module (202); the input of the echo cancellation filter (201) is an audio signal input by an external sound control device (7), the audio signal is filtered and inverted, and then the audio signal is overlapped with an acoustic signal picked up by the error microphone (4), the overlapped signal is used as an output signal of the sub-module, the output signal of the sub-module removes the audio signal input by the external sound control device (7) played by the loudspeaker (2), but comprises control voice of a person, the output signal of the sub-module is sent to the external sound control device (7) through the wireless communication module (51), and the audio signal input by the external sound control device (7) through the wireless communication module (51) is combined to realize acoustic interaction; meanwhile, the output signals of the sub-modules are also used as the input of the self-adaptive algorithm module (202) and the input of the filter updating algorithm module (104), the input of the self-adaptive algorithm module (202) also comprises an audio signal input by an external sound control device (7), the self-adaptive algorithm module (202) outputs a parameter used for updating the echo cancellation filter (201), and the self-adaptive algorithm module (202) carries out self-adaptive adjustment on the parameter of the echo cancellation filter (201) according to the audio signal input by the external sound control device (7) and the output signal of the sub-module, so as to better eliminate the audio signal which is picked up by an error microphone (4) and is input by the external sound control device (7) played by the loudspeaker (2);
the input of the filter updating algorithm module (104) comprises superposition of the output signal of the secondary channel model (103) and the output signal of each echo cancellation sub-module, and the output of the filter updating algorithm module (104) is used for adaptively adjusting the coefficient of the noise reduction filter (101) so as to better inhibit the residual noise signal picked up by the error microphone (4), thereby realizing better active noise reduction effect;
the input of the noise reduction enhancement module (300) is the parameter of each echo cancellation filter (201), and the noise reduction enhancement module (300) superimposes and time-domain smoothes the parameter of each echo cancellation filter (201), and then the result is used as a new parameter of the secondary channel model (103) to realize the real-time update of the secondary channel model (103).
3. An active noise reduction control method capable of acoustic interaction according to claim 2, characterized in that: the noise reduction filter (101), the acoustic feedback channel model (102), the secondary channel model (103) and the echo cancellation filter (201) all adopt FIR filters, wherein the secondary channel model (103) and the echo cancellation filter (201) have the same order.
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