CN112901887A - Pipeline low-frequency noise control device based on electroacoustic coupling - Google Patents
Pipeline low-frequency noise control device based on electroacoustic coupling Download PDFInfo
- Publication number
- CN112901887A CN112901887A CN202110046347.XA CN202110046347A CN112901887A CN 112901887 A CN112901887 A CN 112901887A CN 202110046347 A CN202110046347 A CN 202110046347A CN 112901887 A CN112901887 A CN 112901887A
- Authority
- CN
- China
- Prior art keywords
- loudspeaker
- downstream
- pipe section
- upstream
- noise control
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
- F16L55/02—Energy absorbers; Noise absorbers
- F16L55/033—Noise absorbers
-
- 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
- G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Mechanical Engineering (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
Abstract
The invention aims to provide a pipeline low-frequency noise control device based on electroacoustic coupling, which comprises an upstream loudspeaker, a downstream loudspeaker and a coupling circuit, wherein a main pipeline section for noise control comprises an upstream air inlet pipeline section, a middle silencing pipeline section and a downstream outlet pipeline section, the silencing pipeline section is respectively provided with the upstream loudspeaker and the downstream loudspeaker, the upstream loudspeaker and the downstream loudspeaker are connected through the coupling circuit, the silencing pipeline section is provided with a slide rail capable of transversely translating along a pipeline wall, and the downstream loudspeaker is arranged on the slide rail. The invention can overcome the defects of the traditional H-Q pipe fixing structure and single silencing frequency band. And the electroacoustic coupling characteristic is utilized, the sound path difference between the main pipeline and the side pipeline is created, the flexibility of the silencer is improved, and the structure size is reduced.
Description
Technical Field
The invention relates to a noise control device, in particular to a pipeline noise control device.
Background
The pipeline noise control method is mainly divided into active control and passive control. The active control method mainly utilizes the principle that sound waves are mutually superposed to control noise, the structure of the system is complex, the system can be stable within a certain time, and the applicable working scene is limited. Passive control methods have been developed for many years and are widely used to effectively eliminate mid-to-high frequency noise. According to the noise control principle, when a passive control device is applied to low-frequency noise control, the noise cancellation band is narrow, and the size of the device is limited by the wavelength of sound waves, and is generally large.
The Herschel-Quincke (H-Q) pipe is a typical low-frequency passive control silencing device, and the sound path difference of sound transmitted between a main pipeline and a bypass pipeline is utilized, so that sound waves at the junction of the main pipeline and the bypass pipeline have phase difference, and the silencing effect is achieved. The patent CN101956884A discloses a semi-active device capable of adjusting a bypass pipeline of an H-Q pipe, which widens the effective sound absorption bandwidth of the conventional H-Q pipe device, and makes the muffler device have a good sound absorption effect at medium and low frequencies, but the device complicates the conventional H-Q pipe, adds devices such as a controller, and makes the volume of the muffler device larger, and the sealing performance of the complicated bypass pipeline with variable length is also a difficult problem in engineering. When the H-Q tube is used for low frequency noise control, the low frequency performance is limited by the length of the bypass line, i.e. the length of the bypass line must be long to eliminate the low frequency noise.
Disclosure of Invention
The invention aims to provide a pipeline low-frequency noise control device based on electroacoustic coupling, which has a noise elimination effect in a specific frequency band.
The purpose of the invention is realized as follows:
the invention relates to a pipeline low-frequency noise control device based on electroacoustic coupling, which is characterized in that: the noise control main pipe section comprises an upstream air inlet pipe section, a middle noise elimination pipe section and a downstream outlet pipe section, wherein the upstream air inlet pipe section, the middle noise elimination pipe section and the downstream outlet pipe section are arranged on the noise control main pipe section, the upstream speaker and the downstream speaker are respectively arranged on the noise elimination pipe section, the upstream speaker and the downstream speaker are connected through the coupling circuit, a sliding rail capable of transversely translating along the pipe wall is arranged on the noise elimination pipe section, and the downstream speaker is arranged on the sliding rail.
The present invention may further comprise:
1. the sliding slide rail adjusts the distance between the upstream loudspeaker and the downstream loudspeaker, so that the distance between the upstream loudspeaker and the downstream loudspeaker is matched with the resonance frequency, namely the distance is equal to the half wavelength corresponding to the resonance frequency.
2. The noise enters the main pipe section and then is divided into two paths, the first path is directly transmitted to the downstream loudspeaker through the upstream air inlet pipe section and the middle silencing pipe section, the second path reaches the surface of the upstream loudspeaker to cause the vibration of the vibrating diaphragm to generate induced electromotive force, the downstream loudspeaker produces sound due to the conduction of induced current, and the two paths of sound waves are converged at the downstream loudspeaker to generate destructive interference.
3. And sealing back cavities are arranged outside the upstream loudspeaker and the downstream loudspeaker respectively.
The invention has the advantages that: the invention can overcome the defects of the traditional H-Q pipe fixing structure and single silencing frequency band. And the electroacoustic coupling characteristic is utilized, the sound path difference between the main pipeline and the side pipeline is created, the flexibility of the silencer is improved, and the structure size is reduced.
Drawings
FIG. 1 is a schematic diagram of two paths of sound waves intersecting and overlapping at a downstream loudspeaker;
FIG. 2 is a schematic structural view of the present invention;
fig. 3 shows the transmission loss of the device when the distance between the two loudspeakers is 1 m.
Detailed Description
The invention will now be described in more detail by way of example with reference to the accompanying drawings in which:
with reference to fig. 1-3, the present invention provides a low-frequency noise control device for a pipeline based on electro-acoustic coupling, which includes a main pipe section, an upstream speaker 3, a back cavity 2, an air inlet pipe section 1, a coupling circuit 4, a downstream speaker 5, a back cavity 6, a side plate 7, an outlet pipe section 8, and a limiting block 9.
After the incident sound wave enters the muffled pipe section from the upstream 1 of the main pipe section, it is transmitted from the downstream pipe section 8, where the amplitude of the incident sound wave is reduced. Wherein, a moving coil loudspeaker 3 is arranged on the side surface of the main pipeline near the upstream pipeline section, a closed back cavity 2 is arranged on the back surface of the moving coil loudspeaker, and the upstream loudspeaker is connected with a downstream loudspeaker 5 through a coupling circuit 4. The downstream loudspeaker 5 is mounted on a movable side plate 7 which is movable in translation transversely along the slide of the pipe wall. The upstream and downstream loudspeakers are replaceable, and the loudspeaker most suitable for the noise source can be selected according to different noise source characteristics, namely the peak frequency of the noise source corresponds to the resonance frequency of the selected loudspeaker. The silencing device belongs to a passive silencing device, and the system has no external energy input. Two or more moving coil speakers are placed in sequence along the direction of transmission of noise within the duct. The loudspeaker sets are connected through a coupling circuit. The position parameters and the coupling circuit parameters of the loudspeaker set are adjustable, so that the coverage of different frequency band noises is realized.
The two loudspeakers are connected through a coupling circuit, the two loudspeakers form an equivalent bypass pipe section connected with the main pipe section in parallel, and the inlet pipe section and the outlet pipe section 8 of the loudspeaker 1 are respectively positioned at two ends of the main pipe section. The noise is divided into two paths after entering the main pipe section, one path reaches the surface of the loudspeaker 3 to cause vibration of the vibrating diaphragm and generate induced electromotive force, so that induced current is formed in the two coupled loudspeaker loops, the downstream loudspeaker 5 sounds due to the fact that the induced current is communicated, and the other path is directly transmitted to the downstream loudspeaker 5 through the main pipe section. The two sound waves finally join at the downstream loudspeaker 5, destructive interference is generated due to different transmission phases of the two sound waves, and noise propagating downstream after the two sound waves join is reduced (as shown in fig. 1). At the same time, the downstream moving coil speaker 5 is mounted on a side plate 7 slidable along a slide rail. The position of the downstream loudspeaker 5 is thus adjustable, which provides an additional measure of adjusting the difference in acoustic path between the main duct and the equivalent bypass duct.
A sealed back cavity is arranged outside the loudspeaker set to prevent the loudspeaker from leaking sound to the external environment.
According to acoustic knowledge, when two rows of sound waves with the same wavelength and the same amplitude meet, the sound waves are mutually superposed, and if the phase difference of the two rows of sound waves is 180 degrees, or the phase difference is expressed as odd times of half wavelength, wave crests and wave troughs of the two rows of sound waves just meet and are mutually counteracted to generate a noise elimination effect, which is also a mechanism followed by active noise control. In the invention, the wave crest or the wave trough of the sound wave which is transmitted from the incident pipe section and travels to the upstream loudspeaker can excite the vibration of the loudspeaker diaphragm, and induced electromotive force is generated in the loudspeaker, so that the downstream loudspeaker connected with the loudspeaker can sound. Because the circuit is fast in transmission, the loudspeaker system is equivalent to transmitting the sound wave at the upstream loudspeaker to the downstream immediately with almost no time delay. Thus, based on the principle of superposition of sound waves, when the distance L between the two speakers is exactly equal to (2N-1)/2 times the wavelength (N is 1,2,3 …), the effect of noise cancellation is just achieved. According to the theory of sound wave superposition, when the distance L between two loudspeakers is equal to (4N-3,4N-1)/4 times of wavelength, a certain noise elimination effect is achieved, but when the distance is exactly equal to (2N-1)/2 times of wavelength, the noise elimination effect is best. The design of the invention can lead the distance L between the two loudspeakers to change along with the position movement of the side plate (as shown in figure 2), namely, the position of the downstream loudspeaker can move to the corresponding position along with the slide rail, thereby obtaining the best noise elimination effect of the corresponding frequency band.
The noise reduction effect calculation method of the present invention is as follows.
The mechanical impedance of a moving coil speaker can be expressed as: zm＝δ+jωM+K/jω+A2/jωCa
Wherein C isa＝V/ρ0c0 2The equivalent acoustic reactance is added to a sealed cavity at the back of the loudspeaker, V is the volume of the back cavity, A is the effective vibration area of the surface of the loudspeaker diaphragm, omega is the angular frequency,
is an imaginary number, p0、c0Density of air and speed of sound in air.
The resonance frequency of a loudspeaker can thus be expressed as:
when two loudspeakers are connected to formWhen the loop is closed, the electrical impedance in the loop generates an equivalent mechanical impedance Δ Z (Bl)2/2(Re+jωLe)。
Where Re is the direct current resistance of the speaker, Le is the voice coil inductance, and Bl is the product of the magnetic induction of the magnetic field gap and the effective wire length of the voice coil in the magnetic field (unit: T m).
The resulting equivalent impedance acts on the equivalent damping and equivalent mass of the loudspeaker system, so that the shift in the resonant frequency of the loudspeaker becomes:
the Thiele/Small parameters of the mechanical impedance characteristics of the moving coil loudspeaker are measured as follows: the damping δ is 1.67Ns/M, the mass M is 6.5g, and the stiffness K is 1000N/M. Therefore, according to the theoretical formula, the resonance frequency of a single loudspeaker in the connected system is fL170 Hz. At the resonance frequency, the sound waves transmitted to the surface of the loudspeaker diaphragm more easily excite the diaphragm to vibrate, so that the transmission of sound energy is completed, and therefore, the sound attenuation effect at the resonance frequency range is also the best.
Aiming at the characteristics of the selected loudspeakers, the side plate at the downstream is slid to adjust the distance between the two loudspeakers, so that the distance between the two loudspeakers is matched with the resonance frequency, namely the distance is equal to the half wavelength corresponding to the resonance frequency. The present invention will be described in detail with reference to this position as an example.
The invention selects the inherent characteristic of the loudspeaker, and displaces the downstream side plate with the loudspeaker from L to c0/(2fL) The position is such that the silencing device obtains an optimum silencing effect at this frequency.
According to the control principle, the noise control condition of the pipeline can be obtained:
the effective silencing effect is evaluated by the silencing quantity being more than 5 dB, and the effective silencing frequency band displayed in the figure 3 of the calculation result basically conforms to the theoretically predicted silencing frequency band.
The analysis shows that the silencing device has a good sound absorption effect in a low-frequency band.
Claims (4)
1. A pipeline low-frequency noise control device based on electroacoustic coupling is characterized in that: the noise control main pipe section comprises an upstream air inlet pipe section, a middle noise elimination pipe section and a downstream outlet pipe section, wherein the upstream air inlet pipe section, the middle noise elimination pipe section and the downstream outlet pipe section are arranged on the noise control main pipe section, the upstream speaker and the downstream speaker are respectively arranged on the noise elimination pipe section, the upstream speaker and the downstream speaker are connected through the coupling circuit, a sliding rail capable of transversely translating along the pipe wall is arranged on the noise elimination pipe section, and the downstream speaker is arranged on the sliding rail.
2. The electro-acoustic coupling based pipe low frequency noise control device of claim 1, wherein: the sliding slide rail adjusts the distance between the upstream loudspeaker and the downstream loudspeaker, so that the distance between the upstream loudspeaker and the downstream loudspeaker is matched with the resonance frequency, namely the distance is equal to the half wavelength corresponding to the resonance frequency.
3. The electro-acoustic coupling based pipe low frequency noise control device as claimed in claim 2, wherein: the noise enters the main pipe section and then is divided into two paths, the first path is directly transmitted to the downstream loudspeaker through the upstream air inlet pipe section and the middle silencing pipe section, the second path reaches the surface of the upstream loudspeaker to cause the vibration of the vibrating diaphragm to generate induced electromotive force, the downstream loudspeaker produces sound due to the conduction of induced current, and the two paths of sound waves are converged at the downstream loudspeaker to generate destructive interference.
4. A duct low frequency noise control device based on electro-acoustic coupling according to any of claims 1-3, characterized by: and sealing back cavities are arranged outside the upstream loudspeaker and the downstream loudspeaker respectively.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310148575.7A CN116085572A (en) | 2021-01-14 | 2021-01-14 | Electroacoustic coupling-based pipeline low-frequency noise control device |
| CN202110046347.XA CN112901887A (en) | 2021-01-14 | 2021-01-14 | Pipeline low-frequency noise control device based on electroacoustic coupling |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110046347.XA CN112901887A (en) | 2021-01-14 | 2021-01-14 | Pipeline low-frequency noise control device based on electroacoustic coupling |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310148575.7A Division CN116085572A (en) | 2021-01-14 | 2021-01-14 | Electroacoustic coupling-based pipeline low-frequency noise control device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112901887A true CN112901887A (en) | 2021-06-04 |
Family
ID=76114818
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110046347.XA Pending CN112901887A (en) | 2021-01-14 | 2021-01-14 | Pipeline low-frequency noise control device based on electroacoustic coupling |
| CN202310148575.7A Pending CN116085572A (en) | 2021-01-14 | 2021-01-14 | Electroacoustic coupling-based pipeline low-frequency noise control device |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310148575.7A Pending CN116085572A (en) | 2021-01-14 | 2021-01-14 | Electroacoustic coupling-based pipeline low-frequency noise control device |
Country Status (1)
| Country | Link |
|---|---|
| CN (2) | CN112901887A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20230032254A1 (en) * | 2021-07-23 | 2023-02-02 | Toyota Motor Engineering & Manufacturing North America, Inc. | Asymmetry sound absorbing system via shunted speakers |
| CN116085572A (en) * | 2021-01-14 | 2023-05-09 | 哈尔滨工程大学 | Electroacoustic coupling-based pipeline low-frequency noise control device |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2043416A (en) * | 1933-01-27 | 1936-06-09 | Lueg Paul | Process of silencing sound oscillations |
| CA1298793C (en) * | 1988-05-12 | 1992-04-14 | Adrian William James | Active noise control |
| WO1993022763A1 (en) * | 1992-05-01 | 1993-11-11 | Fujitsu Ten Limited | Noise control device |
| DE4317403A1 (en) * | 1993-05-26 | 1994-12-01 | Nokia Deutschland Gmbh | Arrangement for active sound damping |
| US5693918A (en) * | 1994-09-06 | 1997-12-02 | Digisonix, Inc. | Active exhaust silencer |
| CN1380488A (en) * | 2001-04-18 | 2002-11-20 | 韩国科学技术研究院 | Exhaust noise controller for internal combustion engine |
| EP2116752A1 (en) * | 2008-04-17 | 2009-11-11 | Behr GmbH & Co. KG | Fluid pressure pulsation attenuation device |
| CN101956884A (en) * | 2010-07-15 | 2011-01-26 | 哈尔滨工程大学 | Novel semi-active control device for pipe exhaust noise |
| CN103439126A (en) * | 2013-07-11 | 2013-12-11 | 哈尔滨工程大学 | Experimental measurement method for medium-high frequency acoustic performance of large-pipe-diameter silencer |
| CN107490473A (en) * | 2017-08-31 | 2017-12-19 | 哈尔滨工程大学 | A kind of silencer test device based on gas flow temperature and flow matches |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1357330A (en) * | 1970-07-01 | 1974-06-19 | Secr Defence | Dynamic silencing systems |
| CN203604904U (en) * | 2013-12-05 | 2014-05-21 | 同济大学 | Micro perforated pipe silencer with adjustable frequency |
| WO2019007700A1 (en) * | 2017-07-07 | 2019-01-10 | Tenneco Gmbh | Noise cancellation system |
| CN107631106A (en) * | 2017-08-24 | 2018-01-26 | 江西泰豪军工集团有限公司 | Discharge duct and its sound reduction method |
| JP2019105579A (en) * | 2017-12-14 | 2019-06-27 | 株式会社ウィズソル | Travel device and pipe inspection system |
| CN208703390U (en) * | 2018-06-26 | 2019-04-05 | 香港大学浙江科学技术研究院 | Noise-reducing structure, silene system and pipe-line system |
| CN209763455U (en) * | 2018-12-14 | 2019-12-10 | 中国船舶重工集团公司第七一四研究所 | Pipeline noise active control system, active and passive composite pipeline silencer and pipeline device |
| CN112901887A (en) * | 2021-01-14 | 2021-06-04 | 哈尔滨工程大学 | Pipeline low-frequency noise control device based on electroacoustic coupling |
-
2021
- 2021-01-14 CN CN202110046347.XA patent/CN112901887A/en active Pending
- 2021-01-14 CN CN202310148575.7A patent/CN116085572A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2043416A (en) * | 1933-01-27 | 1936-06-09 | Lueg Paul | Process of silencing sound oscillations |
| CA1298793C (en) * | 1988-05-12 | 1992-04-14 | Adrian William James | Active noise control |
| WO1993022763A1 (en) * | 1992-05-01 | 1993-11-11 | Fujitsu Ten Limited | Noise control device |
| DE4317403A1 (en) * | 1993-05-26 | 1994-12-01 | Nokia Deutschland Gmbh | Arrangement for active sound damping |
| US5693918A (en) * | 1994-09-06 | 1997-12-02 | Digisonix, Inc. | Active exhaust silencer |
| CN1380488A (en) * | 2001-04-18 | 2002-11-20 | 韩国科学技术研究院 | Exhaust noise controller for internal combustion engine |
| EP2116752A1 (en) * | 2008-04-17 | 2009-11-11 | Behr GmbH & Co. KG | Fluid pressure pulsation attenuation device |
| CN101956884A (en) * | 2010-07-15 | 2011-01-26 | 哈尔滨工程大学 | Novel semi-active control device for pipe exhaust noise |
| CN103439126A (en) * | 2013-07-11 | 2013-12-11 | 哈尔滨工程大学 | Experimental measurement method for medium-high frequency acoustic performance of large-pipe-diameter silencer |
| CN107490473A (en) * | 2017-08-31 | 2017-12-19 | 哈尔滨工程大学 | A kind of silencer test device based on gas flow temperature and flow matches |
Non-Patent Citations (6)
| Title |
|---|
| （美）白兰姆著，孙衣禄等译: "《录音室手册》", 30 March 1989, 中国电影出版社 * |
| 刘棣华: "《粘弹阻尼减振降噪应用技术》", 30 April 1990, 宇航出版社 * |
| 左育春: "《电子线路实验150例》", 30 June 1987, 甘肃科学技术出版社 * |
| 张聪燕: "基于多通道有源噪声控制算法的研究及应用", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 * |
| 张锦华编译: "《音箱业余设计和制作实例》", 28 February 1991, 人民邮电出版社 * |
| 王天宇: "水下结构低频辐射噪声线谱主动控制方法研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116085572A (en) * | 2021-01-14 | 2023-05-09 | 哈尔滨工程大学 | Electroacoustic coupling-based pipeline low-frequency noise control device |
| US20230032254A1 (en) * | 2021-07-23 | 2023-02-02 | Toyota Motor Engineering & Manufacturing North America, Inc. | Asymmetry sound absorbing system via shunted speakers |
| US11812219B2 (en) * | 2021-07-23 | 2023-11-07 | Toyota Motor Engineering & Manufacturing North America, Inc. | Asymmetry sound absorbing system via shunted speakers |
Also Published As
| Publication number | Publication date |
|---|---|
| CN116085572A (en) | 2023-05-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103503474B (en) | Dual Drive unit earphone | |
| US4628528A (en) | Pressure wave transducing | |
| US2228886A (en) | Electroacoustical apparatus | |
| EP0963681A2 (en) | Directed acoustic stick radiator | |
| CN112901887A (en) | Pipeline low-frequency noise control device based on electroacoustic coupling | |
| US9762994B2 (en) | Active acoustic meta material loudspeaker system and the process to make the same | |
| Lu et al. | An electronically tunable duct silencer using dielectric elastomer actuators | |
| Trinder et al. | Active noise control in finite length ducts | |
| EP0580579B1 (en) | Noise control apparatus | |
| Gao et al. | Manipulation of low-frequency sound with a tunable active metamaterial panel | |
| US5255321A (en) | Acoustic transducer for automotive noise cancellation | |
| Kohlenberg et al. | Modelling of acoustic liners consisting of helmholtz resonators coupled with a second cavity by flexible walls | |
| JP2006349979A (en) | Noise reduction device | |
| CN112233638B (en) | Design method of adjustable low-frequency silencing structure | |
| Li et al. | Acoustic analysis of coupled loudspeakers for low frequency duct noise reflection | |
| US10522128B2 (en) | Sound attenuation device and method | |
| Prasetiyo et al. | Noise Attenuation of a Duct-resonator System Using Coupled Helmholtz Resonator-Thin Flexible Structures. | |
| JP3143182U (en) | Speaker device | |
| Zhang et al. | Low frequency noise control using coupled loudspeaker and negative impedance circuit | |
| Giouvanakis et al. | Design and construction of loudspeakers with low-Bl drivers for low-frequency active noise control applications | |
| Prezelj et al. | A secondary source configuration for control of a ventilation fan noise in ducts | |
| CN210958677U (en) | Through type phase-reversing tube sound box | |
| Zhao et al. | Two-dimensional acoustic analysis of a flute-like silencer | |
| WO2024208335A1 (en) | Doppler effect-based frequency-shifting apparatus, silencing device, and method | |
| Wang et al. | A compact active sound absorption system compensating near-field effect of the secondary source |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210604 |