CN103310782B - Strong standing wave generation device for symmetric Helmholtz sound sources - Google Patents

Strong standing wave generation device for symmetric Helmholtz sound sources Download PDF

Info

Publication number
CN103310782B
CN103310782B CN201310189787.6A CN201310189787A CN103310782B CN 103310782 B CN103310782 B CN 103310782B CN 201310189787 A CN201310189787 A CN 201310189787A CN 103310782 B CN103310782 B CN 103310782B
Authority
CN
China
Prior art keywords
sound
helmholtz
sound source
standing wave
helmholtz sound
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.)
Active
Application number
CN201310189787.6A
Other languages
Chinese (zh)
Other versions
CN103310782A (en
Inventor
乔正辉
董卫
吴仲武
张庆
杨良华
姚海涛
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Southeast University
Original Assignee
Southeast University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Southeast University filed Critical Southeast University
Priority to CN201310189787.6A priority Critical patent/CN103310782B/en
Publication of CN103310782A publication Critical patent/CN103310782A/en
Application granted granted Critical
Publication of CN103310782B publication Critical patent/CN103310782B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Landscapes

  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

The invention discloses a strong standing wave generation device for symmetric Helmholtz sound sources. The strong standing wave generation device comprises a sound wave guide pipe and the symmetric Helmholtz sound sources arranged at two ends of the sound wave guide pipe; the Helmholtz sound sources are connected with a signal source in parallel through leads, i.e., positive electrodes of a pair of Helmholtz sound sources are simultaneously connected with a positive electrode of the signal source; negative electrodes of the pair of Helmholtz sound sources are simultaneously connected with a negative electrode of the signal source; each Helmholtz sound source comprises an electroacoustic transducer, a cavity and a punching separation board which are positioned on the same axis with the sound wave guide pipe and are sequentially connected in series; a through hole is formed in the middle part of each punching separation board; an end face of each punching separation board is fixedly connected with a pipe mouth of the sound wave guide pipe; and the frequency of radiated sound waves of each electroacoustic transducer is identical with the resonance frequency of the Helmholtz sound sources and is also identical with the certain-order resonance frequency of the sound wave guide pipe. According to the strong standing wave generation device disclosed by the invention, the single-frequency large-amplitude sound voltage and a strong standing wave sound field can be generated by using the small-size electroacoustic transducer.

Description

A kind of strong standing wave generating means of symmetrical Helmholtz sound source
Technical field
The present invention relates to a kind of sound equipment, be specifically related to a kind of strong standing wave generating means of symmetrical Helmholtz sound source.
Background technology
Standing-wave sound field is widely used in sound refrigerator, particulate from fields such as the measurements of the suspension in resonator cavity of the separation gas phase or liquid phase medium, solid particle or drop, sound wave suction cleaner, Demonstration Experiment of Standing Waves In A and discrete state particle size distribution.And these fields standing wave used is single-frequency, general very high to the requirement of standing-wave sound field sound pressure, thus in order to the demand of satisfied increase standing-wave sound field sound pressure in putting into practice, many employings large power, electrically acoustic transducer, realization increases the method that input electrical signal voltage magnitude increases sound pressure amplitudes, and this just causes the volume of electroacoustics transducer comparatively large, heavier-weight, consumption of electric power is higher, thus can limit the application of standing-wave sound field.Most of standing-wave sound field be utilize electroacoustics transducer directly or centre add one end that dividing plate is connected to acoustic waveguide tube indirectly, the other end connects acoustic reflection baffle plate and produces reflective sound wave, thus the incident acoustic wave making reflective sound wave and electroacoustics transducer produce is interfered mutually, forms standing-wave sound field in acoustic waveguide tube.And adopting the method when baffle plate reflection incident acoustic wave, the scattering of passing baffle plate and baffle plate rough surface due to a part of sound wave can produce acoustical energy losses, thus also can limit the application of standing-wave sound field.Patent documentation CN1056176A discloses a kind of resonance tracking system of sound suspending device, adopts the electroacoustics transducer at cylindricality resonator cavity two ends and reflecting surface to produce resonance stationary field by solid particle or suspending drops on the acoustic pressure node of specifying.In this patent application document, the producing method of standing wave just adopts incident wave and reflecting curtain to produce the method for reflection wave on the one hand, and thus when reflecting curtain reflective sound wave, a part of sound wave produces acoustical energy losses through the scattering of baffle plate and baffle plate rough surface; On the other hand, as can be seen from Figure of abstract, electroacoustics transducer resonant cavity is directly connected, thus can easily expect when needing the sound pressure of larger standing-wave sound field to meet larger particle suspension, the input electrical signal of enhancing electroacoustics transducer or replacing is needed to have the electroacoustics transducer of the larger acoustical power of output, be not easy to use common miniature electro-acoustic transducer, reduce the type selecting scope of signal source and electroacoustics transducer.Patent documentation CN102240189A discloses a kind of standing wave type ultrasonic dust collector and dust collection method thereof, the sound radiation face harmony reflecting surface at cavity two ends is adopted to produce standing-wave sound field, suction port is opened at the nodel line place of standing-wave sound field, and utilize acoustic pressure radiant force herein to point in cavity, by this acoustic radiation force, dust is sucked in cavity.In this patent application document, the producing method of standing wave is also the method adopting incident wave and reflecting curtain to produce reflection wave on the one hand, also there is the acoustical energy losses because sound wave causes through baffle plate and the scattering of baffle plate rough surface, on the other hand, as can be seen from Figure of abstract also, electroacoustics transducer is directly connected with cavity, and the sound pressure increasing standing wave is obviously more effective to the suction effect of dust, thus can easily expect when producing the stationary field sound pressure larger than it, also the electroacoustics transducer that the input electrical signal of electroacoustics transducer or replacing have the larger acoustical power of output can only be strengthened, the former requires that signal source has stronger power signal fan-out capability, the parameter request of the latter to transducer is higher, be not easy to use common miniature electro-acoustic transducer, specific large power, electrically acoustic transducer can only be used, type selecting scope is narrower.
Helmholtz resonator has frequency-selecting and amplifies the ability of acoustic pressure.In the application documents of U.S. Patent application US2004/0028246, disclose a kind of loudspeaker apparatus, sound pipe, loudspeaker and sound chamber is utilized to form Helmholtz resonator, by constructing suitable sound pipe structure, realize from exporting the sequential frequency band of Helmholtz resonance frequency to the resonance frequency of sound pipe.Although the effect that the technical scheme of this patented claim realizes makes produced frequency of sound wave make loudspeaker apparatus be provided with certain frequency spectrum fan-out capability like this by consecutive variations in certain frequency spectrum by changing sound pipe length, but the long meeting of sound pipe length causes sound pipe acoustic resistance to increase, and can consume a part of acoustic energy.And utilize Helmholtz resonator to the amplification effect of loudspeaker acoustic pressure and the method giving full play to acoustic pressure amplifying power is not related to.
Summary of the invention
Goal of the invention: in order to overcome the deficiencies in the prior art, the invention provides and miniature electro-acoustic transducer can a kind ofly can be utilized to produce the strong standing wave generating means of the symmetrical Helmholtz sound source of large amplitude acoustic pressure and intense standing wave field.
Technical scheme: for solving the problems of the technologies described above, the strong standing wave generating means of a kind of symmetrical Helmholtz sound source provided by the invention comprises acoustic waveguide tube and is installed on the Helmholtz sound source of acoustic waveguide tube two ends symmetry, described Helmholtz sound source is in parallel with signal source by wire, namely the positive pole of a pair Helmholtz sound source is connected with the positive pole of signal source simultaneously, and the negative pole of a pair Helmholtz sound source is connected with the negative pole of signal source simultaneously; Described Helmholtz sound source comprise with acoustic waveguide tube on the same axis and the electroacoustics transducer of connecting successively, cavity and punching dividing plate, the middle part of described punching dividing plate has through hole, and the described end face of punching dividing plate is fixedly connected with the mouth of pipe of acoustic waveguide tube; Described electroacoustics transducer radiated sound wave frequency is identical with the resonant frequency of Helmholtz sound source, and identical with certain rank resonant frequency of acoustic waveguide tube.
As preferably, when the external diameter of electroacoustics transducer is less than the internal diameter of described cavity, described electroacoustics transducer is connected cover plate with being connected with between cavity.
As preferably, described cavity is prismatic cylindrical.
As preferably, described electroacoustics transducer is small-sized electromagnetic type electroacoustics transducer.
As preferably, described electroacoustics transducer is small-sized piezoelectric formula electroacoustics transducer.
Beneficial effect: the present invention forms strong standing wave generating means by adopting the Helmholtz sound source acoustic waveguide tube installation is symmetrical, has following beneficial effect:
1) miniature electro-acoustic transducer can be used to produce intense standing wave field, reduce the dependence to large power, electrically acoustic transducer;
2) when electroacoustics transducer produces the output of little acoustic pressure, acoustic pressure amplification through Helmholtz sound source also can produce large acoustic pressure output, reduce the demand to signal source output signal strength, realize the voltage magnitude allowing input less when producing identical acoustic pressure, therefore can choice for use low-power level signal source;
3) utilize Helmholtz sound source to produce two arrange row ripple in opposite directions produces intense standing wave field, and acoustic waveguide tube end stop can not be caused when producing reflection wave, and sound wave is through baffle plate or the acoustical energy losses that causes because of rough surface scattering.
Accompanying drawing explanation
Fig. 1 is the structural representation of embodiments of the invention;
Fig. 2 is the structural representation of proving installation in embodiments of the invention;
Fig. 3 is the structural representation of compare device in embodiments of the invention;
Fig. 4 is the sound pressure curve of proving installation in Fig. 2;
Fig. 5 is the sound pressure curve of compare device in Fig. 3;
In figure: 1 acoustic waveguide tube, 2Helmholtz sound source, 3Helmholtz sound source, 4 wires, 5 signal sources, 6 electroacoustics transducers, 7 cavitys, 8 punching dividing plates, 8-1 through hole, 9 connect cover plate, 10 microphones, 11 data acquisition bus, 12 acquisition modules, 13 computers.
Embodiment
Embodiment: the structure of the strong standing wave generating means of a kind of symmetrical Helmholtz sound source of the present embodiment as shown in Figure 1, comprise acoustic waveguide tube 1 and the Helmholtz sound source 2 and 3 being installed on acoustic waveguide tube 1 two ends symmetry, Helmholtz sound source 2 and 3 is in parallel with signal source 5 by wire 4, namely a pair Helmholtz sound source 2 with 3 positive pole be connected with the positive pole of signal source 5 simultaneously, a pair Helmholtz sound source 2 with 3 negative pole be connected with the negative pole of signal source 5 simultaneously; Helmholtz sound source 2 and 3 comprise with acoustic waveguide tube 1 on the same axis and the electroacoustics transducer 6 of connecting successively, cavity 7 and the dividing plate 8 that punches, the middle part of punching dividing plate 8 has through hole 8-1, the external diameter of electroacoustics transducer 6 is less than the internal diameter of cavity 7, is connected with and is connected cover plate 9 between electroacoustics transducer 6 with cavity 7.The shape of cavity 7 is preferably prismatic cylindrical, and electroacoustics transducer 6 selects existing small-sized electromagnetic type electroacoustics transducer or small-sized piezoelectric formula electroacoustics transducer.Electroacoustics transducer 6 radiated sound wave frequency is identical with the resonant frequency of 3 with Helmholtz sound source 2, and identical with certain rank resonant frequency of acoustic waveguide tube 1.
The strong standing wave generating means of above-mentioned symmetrical Helmholtz sound source and the principle of work of method and process are: signal source 5 produces the electric signal with the certain voltage amplitude equal with Helmholtz sound source 2 and 3 resonant frequency, and by wire 4 and Helmholtz sound source 2 with 3 electroacoustics transducer 6 be connected, electroacoustics transducer 6 produces the sound wave of corresponding frequencies and sound pressure amplitude, this sound wave does the to-and-fro movement of similar piston in the air column that cavity 7 and through hole 8-1 are formed, acoustic pressure obtains after enhancing again from through hole 8-1 to acoustic waveguide tube 1 radiation, the sound wave of the Helmholtz sound source 2 and 3 at two ends radiation is in opposite directions at acoustic waveguide tube 1 internal interference, form intense standing wave field.
It is identical to realize frequency with acoustic waveguide tube that the present embodiment constructs Helmholtz sound source in the following manner:
1) according to the resonant frequency f of Helmholtz sound source 0expression formula, the structural parameters of design Helmholtz sound source.The resonant frequency f of Helmholtz sound source 0expression formula is:
f 0 = c 2 π π d n 2 / 4 ( l n + 0.73 d n ) ( l t π d t 2 / 4 )
In formula, c is the velocity of sound, is constant during design, d nfor through-hole diameter, l nfor through hole length, d tfor the diameter of cavity, l tfor the length of cavity.
2) according to the intrinsic intrinsic resonance frequency f of acoustic waveguide tube nexpression formula, design acoustic waveguide tube structural parameters.Intrinsic resonance frequency f nexpression formula be:
f n = nc 2 L x
N=1 in formula, 2 ... for resonance exponent number, c is the velocity of sound, is constant during design, L xthe length of acoustic waveguide tube.
3) will in wave frequency, acoustic pressure nodes (position that sound pressure amplitude is minimum), as known constraints value, designs the structural parameters of Helmholtz sound source and acoustic waveguide tube respectively.If the frequency of standing-wave sound field is f n-1, acoustic pressure nodes is N, represents the condition of known constraints respectively.Further, show that N-1 is acoustic waveguide tube resonant frequency f n-1corresponding rank and the resonant frequency f of Helmholtz sound source 0=f n-1.Therefore, according to calculate the length L of acoustic waveguide tube x.When calculating the structural parameters of Helmholtz sound source, consider using the cavity of cylindrical cross-section as cavity, in conjunction with the resonant frequency of Helmholtz sound source f 0 = c 2 π π d n 2 / 4 ( l n + 0.73 d n ) ( l t π d t 2 / 4 ) Know f 0 ∝ d n 2 l n + 0.73 d n , f 0 ∝ 1 l t , f 0 ∝ 1 d t , Further known f 0with cavity length l tand diameter d tchange sensitive, consider the diameter d at cavity in addition tshould not continuously change (when such as using tubing, the diameter model of tubing is more fixing), block board thickness l nas the length l of through hole n, through-hole diameter d nwith the length l of through hole nall can not change arbitrarily, it can thus be appreciated that, by changing the length l of cavity tchange the resonant frequency f of Helmholtz sound source 0it is method for designing eaily.Further, according to the diameter of selected miniature electro-acoustic transducer, the sheet material of selected thickness and tubing, i.e. through hole length l n, cavity diameter d tfor determined value, determine the size connecting cover plate, and selected suitable through-hole diameter d n, wherein, through-hole diameter d nthe cross-sectional area of acoustic waveguide tube is not more than and the cross-sectional area being less than cavity is determined by the cross-sectional area of through hole.Finally, according to calculate and determine the length l of cavity t.
Adopt above dimension constraint relation, the acoustic waveguide tube of the strong standing wave generating means of a kind of symmetrical Helmholtz sound source of the present embodiment selects pipe, length L x=419mm, diameter 35mm, adopt the design resonance frequency of 3 rank resonant frequency 1.286kHz as acoustic waveguide tube of acoustic waveguide tube; The size of Helmholtz sound source is as follows: through-hole diameter d n=8mm, through hole length l n=5mm, cavity length l t=9mm, cavity diameter d tthe resonant frequency of=35mm, Helmholtz sound source is 1.286kHz; Sheet material and tubing all adopt pmma material.Electroacoustics transducer adopts small-sized electromagnetic type loudspeaker, and diameter is 35mm, and resistance is 10 Ω.The output signal frequency of signal source is 1.286kHz, and amplitude is 0.75V, sinusoidal waveform.
The proving installation of the present embodiment as shown in Figure 2, is in acoustic waveguide tube, 1 add microphone 10, data acquisition bus 11, acquisition module 12 and computer 13 for gathering acoustic pressure data on the basis of Fig. 1; Microphone 10 comprises x 1 ~ 9, wherein x 3x 5x 7fourth class branch and the x of acoustic waveguide tube 1 2x 4x 5x 6x 8six Along ents of acoustic waveguide tube 1, x 1x 9distance acoustic waveguide tube 1 two ends 10mm.
The compare device of above-mentioned proving installation as shown in Figure 3, do not punch dividing plate and cavity is with the difference of Fig. 2, electroacoustics transducer 6 is directly connected with acoustic waveguide tube 1, and the sound source namely in Fig. 3 is not Helmholtz sound source, and other conditions of compare device are all identical with proving installation.
In test process, the acoustic pressure of difference in acoustic waveguide tube 1 is sent in acquisition module 12 by data acquisition bus 11 by group of microphone 10 respectively, finally added up by computer record, generate the sound pressure curve as Fig. 4 and Fig. 5, wherein Fig. 4 is the sound pressure curve of proving installation, Fig. 2 is the sound pressure curve of compare device, by more known for two suite lines, under the identical input signal condition in example signal source, maximum standing wave sound pressure amplitude without formation in acoustic waveguide tube during Helmholtz sound source is 3.3pa, the maximum sound pressure amplitude 40.5pa produced in acoustic waveguide tube when having a Helmholtz sound source, therefore, there is the maximum standing wave sound pressure amplitude formed in acoustic waveguide tube during Helmholtz sound source much larger than the situation without Helmholtz sound source, sound pressure amplitude amplifies 40.5/3.3=12.3 doubly.So the strong standing wave generating means of a kind of symmetrical Helmholtz sound source of the present invention can produce larger standing-wave sound field intensity.

Claims (5)

1. a strong standing wave generating means for symmetrical Helmholtz sound source, is characterized in that comprising: acoustic waveguide tube and the Helmholtz sound source being installed on acoustic waveguide tube two ends symmetry, and described Helmholtz sound source is in parallel with signal source by wire; Described Helmholtz sound source comprise with acoustic waveguide tube on the same axis and the electroacoustics transducer of connecting successively, cavity and punching dividing plate, the middle part of described punching dividing plate has for the through hole through sound wave, and the described end face of punching dividing plate is fixedly connected with the mouth of pipe of acoustic waveguide tube; Described electroacoustics transducer radiated sound wave frequency is identical with the resonant frequency of Helmholtz sound source, and identical with certain rank resonant frequency of acoustic waveguide tube; The resonant frequency of Helmholtz sound source f 0 expression formula is:
In formula, cfor the velocity of sound, d n for through-hole diameter, l n for through hole length, d t for the diameter of cavity, l t for the length of cavity.
2. the strong standing wave generating means of a kind of symmetrical Helmholtz sound source according to claim 1, is characterized in that: the external diameter of described electroacoustics transducer is less than the internal diameter of described cavity, and described electroacoustics transducer is connected cover plate with being connected with between cavity.
3. the strong standing wave generating means of a kind of symmetrical Helmholtz sound source according to claim 2, is characterized in that: described cavity is prismatic cylindrical.
4. the strong standing wave generating means of a kind of symmetrical Helmholtz sound source according to claim 1,2 or 3, is characterized in that: described electroacoustics transducer is small-sized electromagnetic type electroacoustics transducer.
5. the strong standing wave generating means of a kind of symmetrical Helmholtz sound source according to claim 1,2 or 3, is characterized in that: described electroacoustics transducer is small-sized piezoelectric formula electroacoustics transducer.
CN201310189787.6A 2013-05-21 2013-05-21 Strong standing wave generation device for symmetric Helmholtz sound sources Active CN103310782B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201310189787.6A CN103310782B (en) 2013-05-21 2013-05-21 Strong standing wave generation device for symmetric Helmholtz sound sources

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201310189787.6A CN103310782B (en) 2013-05-21 2013-05-21 Strong standing wave generation device for symmetric Helmholtz sound sources

Publications (2)

Publication Number Publication Date
CN103310782A CN103310782A (en) 2013-09-18
CN103310782B true CN103310782B (en) 2015-06-17

Family

ID=49135927

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201310189787.6A Active CN103310782B (en) 2013-05-21 2013-05-21 Strong standing wave generation device for symmetric Helmholtz sound sources

Country Status (1)

Country Link
CN (1) CN103310782B (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105139847B (en) * 2015-08-14 2018-10-02 东南大学 A kind of Acoustic focusing device of enhancing
CN105032110B (en) * 2015-08-20 2016-10-19 东南大学 A kind of two-dimensional acoustic field migrates the device of suspended particulate substance
CN106934234B (en) * 2017-03-09 2021-05-07 南京大学 Method for controlling particles to move along curved track by constructing curved standing wave
CN110099348A (en) * 2018-01-29 2019-08-06 京元电子股份有限公司 Has the microphone element test holder structure of more acoustical generators
CN112179818B (en) * 2020-11-16 2023-12-26 南京工程学院 Pulverized coal fuel particle characteristic testing device
CN115090502B (en) * 2022-06-15 2023-06-23 浙江大学 Device for generating high-level sound waves

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1256259A1 (en) * 2000-02-17 2002-11-13 American Technology Corporation Acoustically asymmetric bandpass loudspeaker with multiple acoustic filters
CN101461254A (en) * 2005-09-20 2009-06-17 皇家飞利浦电子股份有限公司 Audio transducer system with long port
CN102655628A (en) * 2012-02-23 2012-09-05 北京航天计量测试技术研究所 Device and method for detecting high sound pressure-phase shifting characteristic of microphone
CN203260319U (en) * 2013-05-21 2013-10-30 东南大学 Strong standing wave generator of symmetrical Helmholtz sound sources

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1256259A1 (en) * 2000-02-17 2002-11-13 American Technology Corporation Acoustically asymmetric bandpass loudspeaker with multiple acoustic filters
CN101461254A (en) * 2005-09-20 2009-06-17 皇家飞利浦电子股份有限公司 Audio transducer system with long port
CN102655628A (en) * 2012-02-23 2012-09-05 北京航天计量测试技术研究所 Device and method for detecting high sound pressure-phase shifting characteristic of microphone
CN203260319U (en) * 2013-05-21 2013-10-30 东南大学 Strong standing wave generator of symmetrical Helmholtz sound sources

Also Published As

Publication number Publication date
CN103310782A (en) 2013-09-18

Similar Documents

Publication Publication Date Title
CN103310782B (en) Strong standing wave generation device for symmetric Helmholtz sound sources
Lu et al. An electronically tunable duct silencer using dielectric elastomer actuators
CN101841255A (en) Noise power generation device and power generation method
CN105550433B (en) A kind of capacitive micromachined ultrasonic sensor characteristics analysis method
Yuan et al. Low frequency acoustic energy harvester based on a planar Helmholtz resonator
CN203260319U (en) Strong standing wave generator of symmetrical Helmholtz sound sources
CN103248980A (en) Method and device for generating low-frequency sound wave
Li et al. Dual-band piezoelectric acoustic energy harvesting by structural and local resonances of Helmholtz metamaterial
CN107809186B (en) A kind of close-coupled sound wave generating device for broad band low frequency
CN201639508U (en) Noise electricity generator
CN108376542A (en) A kind of gas heater of active noise reduction
CN204887464U (en) Anti low frequency noise's microphone monomer
CN103926018A (en) Liquid temperature measuring device and method
CN204514861U (en) A kind of multilayer material sound absorption performance prediction device
CN106208799A (en) Acoustic energy sampler and apply its sound sensing element
CN103262575A (en) Oscillator device and electronic instrument
CN108964518B (en) Air sound energy gathering and collecting device and system
Roes et al. The effect of reflections on the performance of an acoustic energy transfer system
CN206178108U (en) Liquid crystal display instrument of usable noise electricity generation
KR20110061023A (en) Ultrasonic transducer using planar parallel langevin mounting piezoelectric element, method for manufacturing the ultrasonic transducer, gasmeter using the ultrasonic transducer, distance measuring device using the ultrasonic transducer
CN113630686A (en) High-strength Helmholtz sound source design method based on pattern recognition
CN108417127B (en) Acoustic metasurface experimental device
CN206409225U (en) It is a kind of to improve the acoustic detection probe of penetration range
Li et al. Low-frequency duct noise control using coupled loudspeakers
CN110165937B (en) Sub-wavelength low-frequency sound wave generator with embedded logarithmic solenoid

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C14 Grant of patent or utility model
GR01 Patent grant