Active and passive composite sound absorption device and system

Abstract

The invention discloses an active and passive composite sound absorption device and system. The device comprises a shell, a sound absorption material, a loudspeaker, a front surface microphone, a rear cavity microphone and a controller. A sound absorption material and a loudspeaker are arranged in the shell; one end of the sound absorption material is a sound absorption surface, and external noise can enter the sound absorption material from the sound absorption surface; the sound produced by the loudspeaker can counteract the noise entering the sound absorption material; the front surface microphone is used for acquiring a sound signal absorbed by the sound absorption surface of the sound absorption material; the rear cavity microphone is used for acquiring a sound signal in the cavity of the loudspeaker; and the controller is used for controlling the acoustic impedance of the loudspeaker according to the signals acquired by the front surface generator and the rear cavity microphone. Full-band efficient sound absorption can be realized with a small thickness.

Description

Technical Field

[0001] The present invention relates to the technical field of noise control, and in particular to an active and passive composite sound absorption device and system. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the acceleration of modern industry and urbanization, noise pollution has become a critical issue affecting both the human living environment and the operation of industrial equipment. Traditional passive noise reduction methods, such as porous materials and micro-perforated panels, rely on porous materials and pore structures to absorb sound. While these methods excel at high frequencies, they require significantly increased thickness or volume to be effective at low frequencies, making them generally unsuitable for practical applications.

[0004] Active sound absorption technology uses additional speakers and microphones to build noise feedback control. When size is limited, it can effectively improve the energy dissipation efficiency of low-frequency noise and is an effective supplement to traditional passive methods.

[0005] Traditional active and passive sound absorption structures often adopt a composite form of series connection. Considering factors such as the cavity of the series structure and the rear cavity of the speaker, the volume of the composite structure is still relatively large, which makes it difficult to meet the needs of small-volume sound absorbers. Summary of the Invention

[0006] The present invention proposes an active and passive composite sound absorption device and system, which can achieve high-efficiency sound absorption in the entire frequency band with a relatively small thickness.

[0007] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect, an active-passive composite sound absorption device is proposed, comprising a housing, a sound absorption material, a speaker, a front surface microphone, a rear cavity microphone, and a controller; Sound-absorbing material and a speaker are arranged in the shell; the speaker is embedded in the sound-absorbing material; One end of the sound-absorbing material is the sound-absorbing surface, and external noise can enter the sound-absorbing material from the sound-absorbing surface; the sound emitted by the speaker can offset the low-frequency noise entering the sound-absorbing material; A front surface microphone is used to obtain sound signals from the sound-absorbing surface of the sound-absorbing material; A rear cavity microphone is used to obtain the sound signal in the speaker cavity; The controller is used to control the acoustic impedance of the loudspeaker according to the signals obtained by the front surface microphone and the rear cavity microphone, so as to dissipate the low-frequency noise entering the sound-absorbing material.

[0008] Furthermore, one end of the shell is open, the sound absorbing surface of the sound absorbing material faces the opening, the speaker is embedded in the sound absorbing material, and the sound outlet of the speaker faces the bottom surface of the shell, and the bottom surface of the shell is opposite to the opening of the shell.

[0009] Furthermore, the sound outlet of the speaker is located at the bottom of the speaker, and the top of the speaker adopts a gradual streamlined design.

[0010] Furthermore, there is a set gap between the sound outlet of the speaker and the bottom surface of the housing.

[0011] Furthermore, the speaker is connected to the bottom surface of the housing through a first supporting column.

[0012] Furthermore, one end of the shell is open, the sound-absorbing surface of the sound-absorbing material faces the opening, the speaker is embedded in the inside of the sound-absorbing material, and the sound outlet of the speaker faces the opening of the shell; a scatterer is arranged between the sound outlet of the speaker and the sound-absorbing surface of the sound-absorbing material; the scatterer is used to scatter the sound emitted by the speaker.

[0013] Furthermore, the scatterer is connected to the speaker through a second supporting column.

[0014] Furthermore, the front surface microphone is arranged on the sound absorbing surface of the sound absorbing material; The rear cavity microphone is arranged in the inner cavity of the loudspeaker.

[0015] Furthermore, one or more front surface microphones are provided on the sound absorbing surface of the sound absorbing material.

[0016] Furthermore, the controller is used to obtain sound signals from the front surface microphone and the rear cavity microphone and construct an error, and control the acoustic impedance of the speaker according to the error to dissipate low-frequency noise entering the sound absorbing material from the sound absorbing surface.

[0017] In the second aspect, an active-passive composite sound absorption system is proposed, including an active-passive composite sound absorption device proposed in the first aspect.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes an active-passive composite sound absorption device and system. The device includes a sound absorption device, a front surface microphone, a rear cavity microphone, and a controller. A speaker is also disposed within the sound-absorbing material. The front surface microphone captures sound signals from the sound-absorbing surface of the sound-absorbing material; the rear cavity microphone captures sound signals within the speaker cavity. The controller controls the acoustic impedance of the speaker based on the signals captured by the front surface generator and the rear cavity microphone, so that the sound emitted by the speaker can offset the noise entering the sound-absorbing material. The present invention embeds the speaker in the center of the porous material through an active-passive parallel structure. This allows large-area acoustic impedance control to be achieved using a single, small-area speaker, significantly reducing the thickness of the structure and facilitating its use over large areas.

[0019] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0021] Figure 1 This is a schematic structural diagram of a first structure of an active and passive composite sound absorbing device disclosed in an embodiment; Figure 2 This is a schematic structural diagram of a second structure of an active and passive composite sound absorbing device disclosed in an embodiment; Figure 3 This is a block diagram of the active sound absorption control algorithm disclosed in the embodiment.

[0022] Among them: 1-1, shell; 1-2, sound-absorbing material; 1-3, speaker shell; 1-4, speaker unit; 1-5, power amplifier; 1-6, controller; 1-7, front surface microphone; 1-8, rear cavity microphone; 1-9, first support.

[0023] 2-1. Outer shell; 2-2. Sound-absorbing material; 2-3. Speaker housing; 2-4. Speaker unit; 2-5. Power amplifier; 2-6. Controller; 2-7. Front surface microphone; 2-8. Rear cavity microphone; 2-9. Second support column; 2-10. Scatterer. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0027] In the present invention, terms such as "fixed connection," "connected," and "connection" should be interpreted broadly to mean a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediary. Relevant researchers or technicians in this field may determine the specific meanings of these terms in the present invention based on specific circumstances, and they should not be construed as limitations of the present invention.

[0028] In order to reduce the thickness of the sound absorbing device and ensure the sound absorption effect, the present application proposes an active-passive composite sound absorbing device, which integrates active sound absorption technology with passive sound absorption technology.

[0029] Specifically, the present application proposes an active-passive composite sound absorption device, comprising a housing, a sound absorption material, a speaker, a front surface microphone, a rear cavity microphone, and a controller; Sound-absorbing material and a speaker are arranged in the shell; the speaker is embedded in the sound-absorbing material; One end of the sound-absorbing material is the sound-absorbing surface, and external noise can enter the sound-absorbing material through the sound-absorbing surface; the sound emitted by the speaker can offset the low-frequency noise entering the sound-absorbing material. The sound outlet of the speaker is located at the bottom of the speaker, and the top of the speaker adopts a gradual streamlined design; A front surface microphone is used to obtain sound signals from the sound-absorbing surface of the sound-absorbing material; A rear cavity microphone is used to obtain the sound signal in the speaker cavity; The controller is used to control the acoustic impedance of the loudspeaker according to the signals obtained by the front surface microphone and the rear cavity microphone, so as to dissipate the low-frequency noise entering the sound-absorbing material.

[0030] The outer shell plays a supporting and fixing role and is a rectangular hollow rigid shell with an opening at one end and the rest of the surfaces closed; the sound absorbing surface of the sound absorbing material faces the opening, and the speaker is embedded in the sound absorbing material.

[0031] The sound absorbing material is a porous sound absorbing material, which is filled inside the shell to absorb the medium and high frequency noise incident on the sound absorbing surface.

[0032] The loudspeaker is essentially a sound box. The loudspeaker is rigidly fixed to the inner wall of the shell and embedded in the porous sound-absorbing material and is located at the geometric center of the porous sound-absorbing material.

[0033] The front surface microphone is arranged on the sound absorbing surface of the sound absorbing material; one or more front surface microphones are arranged on the sound absorbing surface of the sound absorbing material, and one or more front surface microphones are evenly attached to the sound absorbing surface of the porous sound absorbing material to obtain the sound signal absorbed by the sound absorbing surface.

[0034] The rear cavity microphone is arranged in the inner cavity of the loudspeaker and is used to obtain the sound signal in the loudspeaker cavity.

[0035] The controller includes an analog-to-digital converter, a signal processor and a digital-to-analog converter. The input end of the controller is connected to the front surface microphone and the rear cavity microphone, and the output end of the controller is connected to the speaker through a power amplifier.

[0036] The controller is used to obtain the sound signals obtained by the front surface microphone and the rear cavity microphone and construct an error, and control the acoustic impedance of the speaker according to the error to dissipate the low-frequency noise entering the sound absorbing material from the sound absorbing surface.

[0037] The controller runs an adaptive active sound absorption control algorithm and implements closed-loop feedback control.

[0038] like Figure 3 As shown, the adaptive active sound absorption control algorithm is implemented by a controller, an acoustic feedback model, auxiliary filters 1, 2, and 3, and an LMS algorithm. The controller is a FIR filter whose input is the sound signal captured by the front surface microphone. If there are multiple front surface microphones, the sound signals captured by all front surface microphones are superimposed. The output of the controller is the algorithm output. After passing through the digital-to-analog conversion module and power amplifier, it controls the acoustic impedance of the speaker, driving the speaker module to produce sound to dissipate low-frequency noise that enters the sound-absorbing material from the sound-absorbing surface. During operation of the control system, the sound emitted by the speaker is also picked up by the front surface microphone. The algorithm uses the acoustic feedback model to predict these signal components. The acoustic feedback model input is the controller output, which is inverted and superimposed with the signal picked up by the front surface microphone. The superimposed signal now contains only external noise information and is input into the controller as a reference signal.

[0039] Furthermore, auxiliary filters 2 and 3 filter the signals picked up by the front surface microphone and the rear cavity microphone, respectively, and then superimpose them to form a composite error signal. Simultaneously, auxiliary filter 1 filters the reference signal to generate a filtered reference signal. Using this composite error signal and the filtered reference signal, combined with the LMS algorithm, the controller's filter coefficients are adaptively updated. This adaptive update mechanism for the controller's filter coefficients can be run all the time or during specific periods.

[0040] The adaptive active sound absorption control algorithm described above modulates the speaker's equivalent acoustic impedance, enabling it to operate in an active sound absorption mode, thereby increasing the equivalent sound absorption coefficient at low frequencies. Combined with porous sound-absorbing materials that are effective at mid- and high-frequency frequencies, the active-passive composite sound absorption device provided in this application achieves efficient sound absorption across the entire frequency band.

[0041] The present application discloses an active-passive composite sound-absorbing device, which organically combines a passive porous sound-absorbing material with an active sound-absorbing loudspeaker, and can achieve high-efficiency sound absorption across the entire frequency band with a relatively small thickness.

[0042] The present application discloses an active and passive composite sound absorption device that can achieve a larger effective sound absorption area using a single loudspeaker, thereby reducing the installation density of the loudspeakers in the application and effectively reducing costs.

[0043] The active and passive composite sound absorption device disclosed in this application can be used in parallel to cover a large sound absorption area, providing a robust distributed multi-channel control system. By embedding a speaker in the center of a porous material through the active and passive parallel structure, a single, small speaker can achieve large-area acoustic impedance control, significantly reducing the thickness of the structure and facilitating wide-area application. Applications can be expanded to include pipes and three-dimensional spaces, such as rooms.

[0044] There are two ways to set up the speakers in this application, one of which is: One end of the housing is open, with the sound-absorbing surface of the sound-absorbing material facing the opening. The speaker is embedded within the sound-absorbing material, with the speaker's sound outlet facing the bottom surface of the housing, which is opposite the opening. A predetermined gap is provided between the speaker's sound outlet and the bottom surface of the housing. The speaker is connected to the bottom surface of the housing via a first support column. This configuration corresponds to the structure of Example 1.

[0045] Another way is: One end of the housing is open, with the sound-absorbing surface of the sound-absorbing material facing the opening. The speaker is embedded within the sound-absorbing material, with the speaker's sound outlet facing the housing's opening. A scatterer is disposed between the speaker's sound outlet and the sound-absorbing surface of the sound-absorbing material. The scatterer is configured to scatter sound emitted by the speaker. The scatterer is connected to the speaker via a second support column. This configuration corresponds to the structure of Example 2.

[0046] The specific structures of the active and passive composite sound absorbing devices of the two speaker arrangement modes are described through Example 1 and Example 2.

[0047] Example 1 like Figure 1 As shown, this embodiment discloses an active-passive composite sound absorbing device, which includes a housing 1-1, a sound absorbing material 1-2, a speaker, a controller, a power amplifier 1-5, a front surface microphone 1-7, and a rear cavity microphone 1-8.

[0048] The outer shell 1-1 is a rectangular hollow rigid shell with an open front surface and closed surfaces. The outer shell has a length and width of 200 mm, a height of 80 mm, and a thickness of 4 mm.

[0049] The sound absorbing material 1-2 is a porous sound absorbing material, which is filled inside the shell 1-1 and is used to absorb the medium and high frequency noise incident on the sound absorbing surface of the sound absorbing material 1-2. The length and width of the porous sound absorbing material are both 196mm and the thickness is 80mm.

[0050] The sound-absorbing surface of the sound-absorbing material 1-2 faces the opening of the shell 1-1, and the sound-absorbing surface of the sound-absorbing material 1-2 is flush with the opening of the shell 1-1; the bottom surface of the sound-absorbing material 1-2 is the surface opposite to the sound-absorbing surface, the bottom surface of the sound-absorbing material 1-2 is in contact with the inner wall of the shell, and a groove for accommodating the speaker is provided on the bottom surface of the sound-absorbing material 1-2.

[0051] The speaker is essentially a sound box, and the top of the speaker rear cavity adopts a gradual streamlined design. Specifically, the speaker includes a speaker shell 1-3 and a speaker unit 1-4; the speaker shell 1-3 is a hollow shell structure, and the top of the speaker shell 1-3 adopts a gradual streamlined design, such as a sphere, a cone or other similar shape with a gradual cross-sectional area, and the speaker unit 1-4 is installed at the bottom of the speaker shell 1-3; that is, the speaker unit 1-4 is arranged opposite to one end of the gradual streamlined design of the speaker shell 1-3.

[0052] The speaker housing 1-3 is installed in the groove of the sound-absorbing material 1-2, and the speaker unit 1-4 faces the groove notch; the bottom of the speaker housing 1-3 is rigidly fixed to the inner wall of the outer shell 1-1 by a number of first support columns 1-9 evenly distributed along its circumference, and is embedded in the interior of the sound-absorbing material 1-2 and is located at its geometric center. At this time, the diaphragm of the speaker unit 1-4, which serves as the sound outlet of the speaker, maintains a set gap of 10 mm with the inner wall of the outer shell to ensure its normal operation. The sound emitted by the speaker through the sound outlet is reflected back into the sound-absorbing material 1-2 by the inner wall of the outer shell, offsetting the low-frequency noise entering the sound-absorbing material 1-2.

[0053] One or more front surface microphones 1-7 are installed on the sound-absorbing surface of the sound-absorbing material 1-2 to obtain the sound signal absorbed by the sound-absorbing surface of the sound-absorbing material. The rear cavity microphone 1-8 is installed in the cavity inside the speaker to measure the sound pressure in the cavity and obtain the sound signal generated by the speaker.

[0054] Controller 1-6 consists of an analog-to-digital converter, a signal processor, and a digital-to-analog converter. Its input is connected to the front surface microphone and the rear cavity microphone, and its output is connected to the power amplifier 1-5 to drive the speaker to produce sound. The signal processor is used to run the adaptive active sound absorption control algorithm and implement closed-loop feedback control.

[0055] Example 2 Since the sound energy of the loudspeaker is high in the front area and low in the edge area, in this embodiment, the installation method of the loudspeaker is improved to produce a new structure of active and passive composite sound absorption device.

[0056] like Figure 2 As shown, this embodiment discloses an active-passive composite sound absorption device, which includes a housing 2-1, a sound absorption material 2-2, a speaker, a controller, a power amplifier 2-5, a front surface microphone 2-7, a rear cavity microphone 2-8 and a scatterer 2-10.

[0057] The outer shell 2-1 is a rectangular hollow rigid shell with an open front surface and closed surfaces. The outer shell has a length and width of 200 mm, a height of 80 mm, and a thickness of 4 mm.

[0058] The sound absorbing material 2-2 is a porous sound absorbing material, which is filled inside the shell 2-1 to absorb the medium and high frequency noise incident on the sound absorbing surface of the sound absorbing material 2-2. The length and width of the porous sound absorbing material are both 196mm and the thickness is 80mm.

[0059] The sound-absorbing surface of the sound-absorbing material 2-2 faces the opening of the shell 2-1, and the sound-absorbing surface of the sound-absorbing material 2-2 is flush with the opening of the shell 2-1; the bottom surface of the sound-absorbing material 2-2 is the surface opposite to the sound-absorbing surface, the bottom surface of the sound-absorbing material 2-2 is in contact with the inner wall of the shell, and a groove for accommodating the speaker and the scatterer 2-10 is provided on the bottom surface of the sound-absorbing material 2-2.

[0060] The speaker includes a speaker housing 2-3 and a speaker unit 2-4.

[0061] The speaker housing 2-3 is a hollow shell structure. The bottom of the speaker is fixed to the inner wall of the outer shell 2-1, which is the surface opposite to the opening of the outer shell 2-1, and the speaker unit 2-4 is installed on the top of the speaker housing 2-3. The diaphragm of the speaker unit 2-4 serves as the sound outlet of the speaker. The diaphragm of the speaker unit 2-4 faces the sound-absorbing surface of the sound-absorbing material 2-2. The sound emitted by the diaphragm directly offsets the noise entering the sound-absorbing material 2-2.

[0062] The scatterer 2-10 is a hollow shell structure, the bottom surface of which is a circular or square plane with an area larger than the diaphragm of the speaker unit 2-4, and the top of which adopts a gradual streamlined design, such as a sphere, cone or other similar shape with a gradual cross-sectional area; the scatterer 2-10 can also be a circular or square plate or perforated plate, and the bottom surface area of ​​the scatterer 2-10 must be larger than the diaphragm area of ​​the speaker unit; in this embodiment, a hemispherical scatterer with a gradual streamlined design is used, and there is a cavity inside the scatterer. The maximum radius of the bottom of the scatterer is 60 mm and the height is 20 mm.

[0063] The bottom surface of the scatterer 2-10 is secured to the top of the speaker housing 2-3 via a plurality of second support columns 2-9 evenly spaced along its circumference. This shields the speaker unit, thereby scattering the sound field and making the sound field more uniform at the front surface of the sound-absorbing material 2-2. The hollow second support columns 2-9 connect the inner cavity of the scatterer to the inner cavity of the speaker housing, thereby expanding the equivalent rear cavity volume of the speaker module and improving its low-frequency performance.

[0064] The bottom of the loudspeaker is rigidly fixed to the inner wall of the housing 2-1, and the loudspeaker is embedded in the porous sound-absorbing material 2-2 and is located at its geometric center.

[0065] One or more front surface microphones 2-7 are installed on the sound-absorbing surface of the sound-absorbing material 2-2 to obtain the sound signal absorbed by the sound-absorbing surface of the sound-absorbing material. A rear cavity microphone 2-8 is installed in the cavity inside the speaker to measure the sound pressure in the cavity and obtain the sound signal generated by the speaker.

[0066] Controller 2-6 consists of an analog-to-digital converter, a signal processor, and a digital-to-analog converter. Its input is connected to the front surface microphone and the rear cavity microphone, and its output is connected to the power amplifier 2-5 to drive the speaker to produce sound. The signal processor is used to run the adaptive active sound absorption control algorithm and implement closed-loop feedback control.

[0067] This embodiment scatters the sound emitted by the speaker by providing a scatterer 2-10, thereby ensuring the uniformity of the sound attenuation and thereby improving the sound attenuation performance of the device.

[0068] Example 3 In this embodiment, an active-passive composite sound absorption system is disclosed, including an active-passive composite sound absorption device proposed in Example 1 or Example 2.

[0069] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. An active and passive composite sound absorbing device, characterized in that: It includes a housing, a sound absorbing material, a speaker, a front surface microphone, a rear cavity microphone and a controller; Sound absorbing material and a speaker are arranged in the shell; The speakers are embedded in the sound-absorbing material; One end of the sound-absorbing material is the sound-absorbing surface, and external noise can enter the sound-absorbing material from the sound-absorbing surface; The sound emitted by the speaker can offset the noise entering the sound-absorbing material; A front surface microphone is used to obtain sound signals from the sound-absorbing surface of the sound-absorbing material; A rear cavity microphone is used to obtain the sound signal in the speaker cavity; The controller is used to control the acoustic impedance of the loudspeaker according to the signals obtained by the front surface generator and the rear cavity microphone.

2. The active-passive composite sound absorbing device according to claim 1, characterized in that: One end of the shell is open, the sound absorbing surface of the sound absorbing material faces the opening, the speaker is embedded in the sound absorbing material, and the sound outlet of the speaker faces the bottom surface of the shell, and the bottom surface of the shell is opposite to the opening of the shell.

3. The active-passive composite sound absorbing device according to claim 2, characterized in that: There is a set gap between the sound outlet of the speaker and the bottom surface of the housing.

4. The active-passive composite sound absorbing device according to claim 2, characterized in that: The loudspeaker is connected to the bottom surface of the housing through a first supporting column.

5. The active-passive composite sound absorbing device according to claim 1, characterized in that: One end of the housing is open, the sound absorbing surface of the sound absorbing material faces the opening, the speaker is embedded in the sound absorbing material, and the sound outlet of the speaker faces the opening of the housing; a scatterer is arranged between the sound outlet of the speaker and the sound absorbing surface of the sound absorbing material; Diffusers are used to scatter the sound emitted by the speakers.

6. The active-passive composite sound absorbing device according to claim 5, characterized in that: The scatterer is connected to the loudspeaker through a second supporting column.

7. The active-passive composite sound absorbing device according to claim 1, characterized in that: The front surface microphone is arranged on the sound absorbing surface of the sound absorbing material; The rear cavity microphone is arranged in the inner cavity of the loudspeaker.

8. The active-passive composite sound absorbing device according to claim 7, characterized in that: One or more front surface microphones are arranged on the sound absorbing surface of the sound absorbing material.

9. The active-passive composite sound absorbing device according to claim 1, characterized in that: The controller is used to obtain the sound signals of the front surface generator and the rear cavity microphone and construct an error, and control the sound of the speaker according to the error to offset the noise entering the sound absorbing material from the sound absorbing surface.

10. An active and passive composite sound absorption system, characterized in that: An active-passive composite sound absorbing device comprising any one of claims 1-9.

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