Broadband and wide-angle sound wave retroreflection structure based on acoustic channel array

Abstract

The invention belongs to the technical field of acoustic sensing and detection, and provides a broadband and wide-angle sound wave retroreflection structure based on an acoustic channel array, which aims at solving the problems that the effective incident angle of the existing sound wave retroreflection device is smaller, the working frequency band is narrower, the working environment is limited and a plurality of frequency bands cannot be detected, and comprises a plurality of ultra-wideband sound wave retroreflection structure units, each unit comprises three U-shaped acoustic channels of nested structures, protruding structures are arranged in the acoustic channels, and the opening ends of all the ultra-wide-band sound wave retroreflection structure units are located on the same plane, so that the tops of all the ultra-wide-band sound wave retroreflection structure units are flush, and the retroreflection effect of sound waves can be achieved; according to the invention, most sound waves of audible sound frequency bands which can be heard by human ears can be covered, and the device has the characteristics of wide frequency band and wide-angle working, can detect sound waves which are incident at different frequencies and in different directions, and increases the detection range.

Description

Technical Field

[0001] The invention belongs to the technical field of acoustic sensing and detection, and in particular relates to a broadband and wide-angle sound wave back reflection structure based on an acoustic channel array. Background Art

[0002] Acoustic wave retroreflection devices can make the incident sound waves emit in the opposite direction of the incident direction. They can be used in many fields such as remote sensing, non-destructive testing, medical imaging, music monitoring and underwater communication. In environmental monitoring, they are used to detect the gas composition or pollutant concentration in the atmosphere. By emitting light or sound waves of specific wavelengths into the atmosphere, the retroreflector can reflect these wavelengths and transmit the information back to the detector, thereby analyzing the concentration of gas or particulate matter. In industry, retroreflectors are widely used in non-destructive testing technology, especially in detecting internal defects of materials. Ultrasonic retroreflectors can be used to detect internal cracks or cavities in metals, composite materials, etc. By analyzing the characteristics of the echo, the structural integrity and quality of the material can be judged. 3.6kHz~12kHz belongs to the sound wave range audible to the human ear, so controlling the sound wave retroreflection in this frequency band can be applied to human voice or instrument monitoring. In the process of music production and recording, retroreflectors can be used to improve the sound quality and sound transmission effect. Especially when high-fidelity sound monitoring is required, retroreflectors that can accurately reflect sound waves can help capture clearer audio signals and help sound engineers make more precise adjustments. Currently, there are many ways to achieve sound wave retroreflection, such as superlenses and metasurfaces.

[0003] At present, the existing acoustic wave reflectors have a small effective incident angle, a narrow working frequency band, a limited working environment, are unable to detect multiple frequency bands, and have a small detection range, and are unable to adapt to a wider range of application scenarios. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a broadband, wide-angle sound wave reflection structure based on an acoustic channel array in order to solve the problems of narrow frequency band and limited incident angle of the current sound wave reflection device. When the sound wave is incident on the ultra-wideband sound wave reflection array structure of the present invention, the sound wave can be emitted from the direction of the sound wave incident, interfere with the incident sound wave to form a standing wave, and the sound wave achieves a reflection effect.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An ultra-wideband sound wave back reflection structural unit based on acoustic channels comprises three U-shaped acoustic channels of acoustic rigid material, wherein the three U-shaped acoustic channels are nested from outside to inside and are respectively a first acoustic channel, a second acoustic channel and a third acoustic channel, the thickness of the acoustic channel wall is less than the central wavelength of the incident sound wave, the widths w of the three U-shaped acoustic channels are the same, the three U-shaped acoustic channels are filled with gas medium, a plurality of protrusion structures are arranged in the three U-shaped acoustic channels, and each protrusion structure has the same spacing with adjacent protrusion structures.

[0007] Furthermore, the width w of the U-shaped acoustic channel is of the same order of magnitude as the central wavelength of the incident acoustic wave.

[0008] Furthermore, the spacing between the protruding structures is on the order of sub-wavelength of the central wavelength of the incident sound wave, and the thickness of the protruding structures is the same as the thickness of the acoustic channel wall.

[0009] Furthermore, the first acoustic channel contains the first protruding structure, the second acoustic channel contains the second protruding structure, and the third acoustic channel contains the third protruding structure. The first protruding structure is the shortest, the third protruding structure is the longest, and the second protruding structure is between the first and third protruding structures in length.

[0010] An ultra-wideband sound wave echo reflection array structure based on an acoustic channel, based on the above-mentioned ultra-wideband sound wave echo reflection structure unit based on an acoustic channel, includes a plurality of ultra-wideband sound wave echo reflection structure units arranged in parallel, the outer wall of each ultra-wideband sound wave echo reflection structure unit is fitted with the adjacent ultra-wideband sound wave echo reflection structure unit, the opening ends of all the ultra-wideband sound wave echo reflection structure units are located in the same plane, so that the tops of all the ultra-wideband sound wave echo reflection structure units are flush.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The present invention is a sound wave back reflection structure based on an acoustic channel array, which is composed of a plurality of back reflection units arranged in parallel, each unit is composed of three nested U-shaped channels, each channel has a periodic protrusion of a specific length, and the channel protrusion gradually becomes smaller from the inside to the outside. In free space, when a beam of sound waves is incident on the surface of the sound wave back reflection structure of the present invention, the sound waves can be emitted from the direction of the sound wave incidence. The present invention can achieve the back reflection effect for most incident angles of 3.6kHz to 12kHz sound waves, and can cover most sound waves in the audible sound frequency band audible to the human ear. The present invention has the characteristics of wide-band and wide-angle operation, and can detect sound waves incident at different frequencies and different directions, thereby increasing the detection range. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the sound wave back reflection structure of the present invention;

[0014] Figure 2 is a schematic diagram of the sound wave back reflection structural unit of the present invention;

[0015] Figure 3 The numerical simulation result of the grayscale distribution diagram of the absolute value of the sound pressure when an 11kHz sound wave enters the structure of the present invention at an incident angle of 20°;

[0016] Figure 4 It is the numerical simulation result of the grayscale distribution diagram of the absolute value of the sound pressure of the present invention when an 11kHz sound wave is incident at an incident angle of 65°;

[0017] Figure 5 The numerical simulation result of the grayscale distribution diagram of the absolute value of the sound pressure of the structure of the present invention when a 3.6kHz sound wave is incident on the structure at an incident angle of 45°;

[0018] Figure 6 The numerical simulation result of the grayscale distribution diagram of the absolute value of the sound pressure of the structure of the present invention when a sound wave of 12kHz is incident on the structure at an incident angle of 45°;

[0019] Figure 7 This is a graph of the retroreflection efficiency of the present invention, with the horizontal axis being the frequency, the vertical axis being the incident angle, and the right side being the efficiency marking color.

[0020] In the figure: 1 - first acoustic channel; 2 - second acoustic channel; 3 - third acoustic channel; 4 - first protruding structure; 5 - second protruding structure; 6 - third protruding structure; 7 - acoustic channel pipe wall. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some examples of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] like Figure 1 Shown is a broadband, wide-angle sound wave reflection structure based on an acoustic channel array, wherein the structure is composed of a plurality of units arranged in parallel, the surface of each unit is a plane, and the surface of the array formed by the units is also a plane; the structure is composed of an acoustic rigid material, and the channel is filled with a gas medium.

[0023] like Figure 2 As shown: Each unit is composed of three nested U-shaped channels.

[0024] The width w of each channel is of the same order of magnitude as the central wavelength of the incident acoustic wave.

[0025] Each channel has periodic protrusions of specific length.

[0026] The intervals between periodic protrusions in the channel are on the order of sub-wavelength.

[0027] The period of the protrusion units in each channel is one third of the working center wavelength.

[0028] The length of the protrusion in each unit channel gradually shortens from the inside to the outside, with the innermost channel having the longest protrusion and the outermost channel having the shortest protrusion.

[0029] The thickness of the acoustic channels and protrusions should be smaller than the wavelength of the incident wave.

[0030] The width of the unit incident surface formed by the channel multiplied by the number of units should be greater than the width of the incident sound wave.

[0031] The acoustic channel wall and the protruding structure are made of any material, including resin, rock wool board or metal.

[0032] The gas filled in the acoustic channel is air, nitrogen or other gases.

[0033] Example

[0034] In this example, the working center wavelength of the sound wave is designed to be 0.049m, corresponding to a sound wave with a frequency of 11kHz. The material of the channel wall and the protruding structure of each reflective unit is resin, with a Young's modulus of 4.5GPa and a mass density of 1117kg / m 3 The gas filled in the acoustic channel is air (sound velocity 343m / s, mass density 1.293kg / m 3 ). The structure of the back reflection array is as follows Figure 1 As shown, it is composed of several retroreflective units arranged in parallel; the retroreflective unit structure is as follows Figure 2 As shown, it is composed of three layers of nested reflective channels. The thickness of each channel wall is 0.001m, the width of the vertical channel is 0.009m, and the width of the horizontal channel is 0.004m. The height of the protruding structure in each acoustic channel is 0.002979m, 0.001944m, and 0.0005m from the inside to the outside, respectively. The thickness of the protruding structure in each channel is 0.001m, and the interval period is 0.005m. When the height of the first protruding structure 4 is 0, that is, the first acoustic channel 1 is a plane, the reflective effect is the same as that of the present embodiment.

[0035] When a sound wave is incident on the surface of the ultra-wideband sound wave echo reflection array structure of the present invention at an incident angle of 20°, the sound wave is emitted at a reflection angle of 20° and interferes with the incident sound wave to form a standing wave. Figure 3 It is a grayscale distribution diagram of the absolute value of the total sound pressure field of the numerical simulation of this embodiment.

[0036] When a sound wave is incident on the surface of the ultra-wideband sound wave back reflection array structure of the present invention at an incident angle of 65°, the sound wave is emitted at 65° and interferes with the incident sound wave to form a standing wave. Figure 4 It is a grayscale distribution diagram of the absolute value of the total sound pressure field of the numerical simulation of this embodiment.

[0037] pass Figure 3 , Figure 4 The simulation results show that the ultra-wideband sound wave back reflection array structure of the present invention has a good back reflection effect on the central wavelength of the sound wave.

[0038] The present invention can achieve the back reflection effect for most incident angles of 3.6kHz to 12kHz sound waves, such as Figure 7 As shown in the table below, the incident angles at which the acoustic wave reflection efficiency in different frequency bands is higher than 50% are shown in the table below:

[0039] Table 1 Range of acoustic wave reflection efficiency higher than 50% at different frequencies

[0040]

[0041] The present invention can cover most of the sound waves in the audible frequency band that can be heard by human ears. The present invention has the characteristics of wide-band and wide-angle operation, and can detect sound waves incident at different frequencies and different directions, thereby increasing the detection range.

[0042] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ultra-wideband sound wave back reflection structural unit based on an acoustic channel, characterized in that: The invention comprises three U-shaped acoustic channels made of acoustic rigid materials, wherein the three U-shaped acoustic channels are nested from the outside to the inside and are respectively a first acoustic channel (1), a second acoustic channel (2) and a third acoustic channel (3), the thickness of the acoustic channel wall (7) is less than the central wavelength of the incident sound wave, the widths w of the three U-shaped acoustic channels are the same, the three U-shaped acoustic channels are filled with gas medium, and a plurality of protruding structures are arranged in the three U-shaped acoustic channels, and the spacing between each protruding structure and the adjacent protruding structure is the same.

2. The ultra-wideband sound wave back reflection structure unit based on acoustic channel according to claim 1, characterized in that: The width w of the U-shaped acoustic channel is of the same order of magnitude as the central wavelength of the incident sound wave.

3. The ultra-wideband sound wave back reflection structure unit based on acoustic channel according to claim 1, characterized in that: The spacing between the protruding structures is at the sub-wavelength level of the central wavelength of the incident sound wave, and the thickness of the protruding structures is the same as the thickness of the acoustic channel wall (7).

4. The ultra-wideband sound wave back reflection structure unit based on acoustic channel according to claim 1, characterized in that: The first acoustic channel (1) contains a first protruding structure (4), the second acoustic channel (2) contains a second protruding structure (5), and the third acoustic channel (3) contains a third protruding structure (6). The first protruding structure (4) is the shortest, the third protruding structure (6) is the longest, and the second protruding structure (5) is between the first protruding structure (4) and the third protruding structure (6) in length.

5. An ultra-wideband acoustic wave echo reflection array structure based on an acoustic channel, based on the ultra-wideband acoustic wave echo reflection structure unit based on an acoustic channel according to any one of claims 1 to 4, characterized in that: It comprises a plurality of parallel arranged ultra-wideband sound wave echo reflection structural units, the outer wall of each ultra-wideband sound wave echo reflection structural unit is fitted with the adjacent ultra-wideband sound wave echo reflection structural unit, the opening ends of all the ultra-wideband sound wave echo reflection structural units are located in the same plane, so that the tops of all the ultra-wideband sound wave echo reflection structural units are flush.

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