Low-frequency sound wave radiation enhancement structure and sound emitting device

Abstract

The application discloses a low-frequency sound wave radiation enhancement structure and a sound emitting device. The low-frequency sound wave radiation enhancement structure comprises a sound inlet pipe, a cavity and a sound outlet pipe. The sound inlet pipe is used for being connected with a sound source. The cavity comprises a sound cavity. The sound inlet pipe is connected with the cavity and communicates with the sound cavity. The sound outlet pipe is connected with the cavity and communicates with the sound cavity. The cross-sectional area of the sound outlet pipe is smaller than that of the sound cavity. The sound of the sound source is transmitted into the cavity through the sound inlet pipe, is emitted from the sound outlet pipe after resonance in the sound cavity, the low-frequency radiation efficiency of the sound wave can be effectively enhanced, the sound pressure level of the low-frequency band is improved, the power of the sound source does not need to be increased, and the reliability of the sound source in operation can be ensured.

Description

Technical Field

[0001] This invention relates to the field of loudspeaker technology, and in particular to a low-frequency sound wave radiation enhancement structure and a sound-generating device. Background Technology

[0002] Electronic devices often contain speakers and sound transmission tubes that communicate with the speaker's sound outlet. These tubes connect to the outside of the electronic device's casing to project sound from the speaker. The size of the speaker's sound outlet must consider its impact on the electronic device's structure, and therefore cannot be too large. For example, the sound outlet of a mobile phone speaker is limited by the phone's size and structural strength. Similarly, in some smart beds, gaming chairs, and pillows, the area available for speaker placement on both sides is extremely limited, and the sound outlets are relatively small. Therefore, these speaker systems inherently suffer from insufficient low-frequency sound wave radiation.

[0003] Current improvement methods typically involve creating a front cavity (the sound tube can serve as its front cavity) in front of the speaker, fabricating the front cavity with a gradually increasing area, similar to a common loudspeaker. This gradually increases the opening area, resulting in a gradual change in impedance and thus increasing the speaker's sound wave radiation efficiency. However, this structure has certain limitations: First, the gradually increasing area of ​​the structure results in a relatively large opening for radiating sound waves; second, the improvement in low-frequency radiation efficiency is not significant. For example, if it is necessary to enhance the sound waves in the 100-300 Hz low-frequency range (the main frequency of human voice), the required opening area needs to reach the meter scale.

[0004] Therefore, for such small-diameter loudspeaker systems, the low-frequency sound pressure level is often increased by forcibly increasing the power. However, this method results in large vibration amplitude, the voice coil is prone to dislodgement, and it also introduces excessive distortion, affecting the overall sound effect.

[0005] Therefore, it is necessary to improve the existing technology to overcome the aforementioned defects. Summary of the Invention

[0006] The purpose of this invention is to provide a low-frequency sound wave radiation enhancement structure and a sound generating device, which can enhance the low-frequency acoustic performance of a small-diameter loudspeaker system.

[0007] To achieve the above-mentioned objectives, in one aspect, the present invention proposes a low-frequency acoustic radiation enhancement structure, characterized in that it comprises:

[0008] The sound inlet pipe is used to connect to the sound source;

[0009] A cavity, including a acoustic cavity, wherein the sound inlet pipe is connected to and communicates with the cavity; and...

[0010] The sound outlet tube is connected to the cavity and communicates with the acoustic cavity. The cross-sectional areas of the sound outlet tube and the sound inlet tube are smaller than the cross-sectional area of ​​the acoustic cavity.

[0011] Furthermore, the inlet pipe and the outlet pipe are connected to opposite sides of the cavity.

[0012] Furthermore, the sound inlet tube and the sound outlet tube are arranged on the same axis.

[0013] Furthermore, the acoustic impedance of the materials of the inlet pipe, cavity, and outlet pipe is greater than or equal to 300 times the air acoustic impedance.

[0014] Furthermore, the cavity is made of an elastic material, and the material hardness of the sound outlet tube is greater than that of the cavity.

[0015] Furthermore, the sound inlet tube is made of rubber, silicone, or plastic; the cavity is made of silicone or soft rubber; and the sound outlet tube is made of plastic.

[0016] Furthermore, the sound outlet tube is located inside the cavity, or the sound outlet tube is located outside the sound cavity, or the sound outlet tube is partially located inside the sound cavity and partially located outside the cavity.

[0017] Furthermore, the cavity includes two or more acoustic cavities, and each acoustic cavity is provided with a corresponding sound outlet tube.

[0018] Furthermore, at least two acoustic cavities have different volumes, or at least two sound outlet tubes have different cross-sectional areas or lengths.

[0019] Furthermore, the cavity includes a front cavity communicating with the sound inlet pipe and a sound channel connecting the sound cavity and the front cavity.

[0020] Furthermore, the cavity also includes an interconnected plate and a block, the plate being used to separate the acoustic cavity, the block being used to separate the front cavity and the acoustic cavity, and the width of the block being greater than the thickness of the plate.

[0021] On the other hand, the present invention proposes a sound-generating device, comprising:

[0022] loudspeakers; and,

[0023] As described in any of the preceding low-frequency sound wave radiation enhancement structures, the loudspeaker is connected to the sound inlet tube.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The low-frequency sound wave radiation enhancement structure of the present invention is provided with an inlet pipe for connecting to a sound source, a cavity connected to the inlet pipe, and an outlet pipe connected to the cavity. The cross-sectional area of ​​the cavity is larger than that of the outlet pipe. After the sound from the sound source enters the cavity through the inlet pipe, it resonates in the cavity and is then transmitted out through the outlet pipe. This can effectively enhance the low-frequency radiation efficiency of the sound wave, improve the sound pressure level in the low-frequency band and the performance of human voice. Moreover, the low-frequency enhancement effect can be achieved using a common sound source (loudspeaker) without increasing the power of the sound source, which helps to ensure the reliability of the sound source operation.

[0026] 2. As an improvement, the low-frequency sound wave radiation enhancement structure has two or more acoustic cavities, each capable of resonating with sound waves, thereby further improving radiation efficiency and enhancing the low-frequency effect. Furthermore, by changing the volume of the acoustic cavities, or altering the cross-sectional area and length of the sound outlet tube, the resonant frequency of the low-frequency sound wave radiation enhancement structure can be altered, thereby enhancing sound pressure in different frequency bands for even better results. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the low-frequency sound wave radiation enhancement structure in Embodiment 1 of the present invention.

[0028] Figure 2 This is a three-dimensional cross-sectional view of the low-frequency sound wave radiation enhancement structure in Embodiment 1 of the present invention.

[0029] Figure 3 This is a cross-sectional view of the low-frequency acoustic radiation enhancement structure in Embodiment 1 of the present invention.

[0030] Figure 4 This is a schematic diagram showing that the sound outlet tube of the low-frequency sound wave radiation enhancement structure in this invention is located outside the sound cavity.

[0031] Figure 5 This is a schematic diagram of the sound tube of the low-frequency sound wave radiation enhancement structure in this invention, with part of it located inside the sound cavity and part of it located outside the cavity.

[0032] Figure 6 This is a schematic diagram of the low-frequency sound wave radiation enhancement structure in Embodiment 2 of the present invention.

[0033] Figure 7 This is a three-dimensional cross-sectional view of the low-frequency sound wave radiation enhancement structure in Embodiment 2 of the present invention.

[0034] Figure 8 This is a cross-sectional view of the low-frequency acoustic radiation enhancement structure in Embodiment 2 of the present invention.

[0035] Figure 9 This is a perspective view of the low-frequency sound wave radiation enhancement structure of the first example of the present invention.

[0036] Figure 10This is a cross-sectional view of the low-frequency acoustic radiation enhancement structure of the first example of the present invention.

[0037] Figure 11 The graph shows the frequency response curves of the low-frequency sound wave radiation enhancement structure in the first example and the comparative example.

[0038] Figure 12 This is a schematic diagram of the low-frequency sound wave radiation enhancement structure in Embodiment 3 of the present invention.

[0039] Figure 13 This is a schematic diagram of the low-frequency sound wave radiation enhancement structure from another perspective in Embodiment 3 of the present invention.

[0040] Figure 14 This is a three-dimensional cross-sectional view of the low-frequency sound wave radiation enhancement structure in Embodiment 3 of the present invention.

[0041] Figure 15 This is a cross-sectional view of the low-frequency acoustic radiation enhancement structure in Embodiment 3 of the present invention.

[0042] Figure 16 This is a perspective view of the low-frequency sound wave radiation enhancement structure of the second example of the present invention.

[0043] Figure 17 This is a cross-sectional view of the low-frequency acoustic radiation enhancement structure of the second example of the present invention.

[0044] Figure 18 The graph shows the frequency response curves of the low-frequency sound wave radiation enhancement structure in the second example and the comparative example.

[0045] Figure 19 This is a cross-sectional view of the low-frequency acoustic radiation enhancement structure of the third example of the present invention.

[0046] Figure 20 These are the frequency response curves of the low-frequency sound wave radiation enhancement structures in the second and third examples and the comparative example. Detailed Implementation

[0047] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0048] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0049] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0050] Example 1

[0051] like Figures 1 to 3 As shown, a low-frequency sound wave radiation enhancement structure corresponding to a preferred embodiment of the present invention includes an inlet pipe 1, a cavity 2 and an outlet pipe 3, with the cavity 2 connected between the inlet pipe 1 and the outlet pipe 3.

[0052] The inlet pipe 1 is used to connect with a sound source to receive sound emitted from the sound source. The sound received through the inlet pipe 1 passes through the cavity 2 and is emitted through the outlet pipe 3. The sound source is, for example, a loudspeaker. When the inlet pipe 1 is connected to the loudspeaker, it is in close contact with the loudspeaker's sound-emitting surface around its perimeter or is sealed by a sealant to reduce or prevent sound waves from leaking out from the gap between the loudspeaker and the inlet pipe 1, thereby reducing sound leakage and the reduction of sound wave energy.

[0053] Cavity 2 includes acoustic cavity 20. Inlet pipe 1 and outlet pipe 3 are both connected to acoustic cavity 20. Sound waves enter cavity 2 through inlet pipe 1 and resonate within cavity 2 before being emitted from outlet pipe 3. This significantly increases the low-frequency radiation effect and the sound pressure level in the low-frequency range. To ensure reliable resonance of sound waves within acoustic cavity 20, the cross-sectional areas of inlet pipe 1 and outlet pipe 3 are both smaller than the cross-sectional area of ​​acoustic cavity 20. The cross-sectional area refers to the area of ​​the cross section obtained by cutting with a plane perpendicular to the central axis 11 of outlet pipe 3 as the cutting plane.

[0054] Specifically, the sound outlet tube 3 acts as the acoustic mass in this system, while the acoustic cavity 20 acts as the acoustic capacitive (spring). Under the influence of a specific frequency band of sound pressure transmitted through the sound inlet tube 1, the entire spring-mass system resonates. At this time, the volume velocity caused by the acoustic mass vibration of the sound outlet tube 3 increases significantly, thereby increasing the output efficiency of that frequency band. By controlling the relevant parameters of the acoustic cavity 20 and the sound outlet tube 3, the frequency band of the resonant sound wave can be controlled. In the entire system, the sound outlet tube 3 and the acoustic cavity 20 are equivalent to acoustic mass and acoustic capacitive, respectively. To ensure their reliable function, their dimensions (e.g., length, width, height, or diameter) are preferably much smaller than the wavelength corresponding to the resonant frequency of the sound wave and the low-frequency sound wave radiation enhancement structure. As a preferred embodiment, the dimensions of both the sound outlet tube 3 and the acoustic cavity 20 are less than one-tenth of the wavelength corresponding to the resonant frequency of the low-frequency sound wave radiation enhancement structure.

[0055] The resonant frequency of a low-frequency acoustic radiation enhancement structure can be expressed by the following formula:

[0056]

[0057] in, The sound quality brought by the sound outlet tube 3 is expressed by the formula: In the formula, ρ0 is the density of the gas in the tube, l is the tube length, and S is the cross-sectional area of ​​the tube. Ca is the acoustic volume of the acoustic cavity 20, expressed by the formula: In the formula, V is the volume of the acoustic cavity 20, ρ0 is the density of the gas inside, and c0 is the speed of sound of the gas.

[0058] The sound quality and operating frequency can be flexibly adjusted by changing the length and area of ​​the sound outlet tube 3. Generally speaking, the longer the tube and the smaller the area, the greater the sound quality and the lower the corresponding resonant frequency. Furthermore, the larger the volume of the sound cavity 20, the greater the acoustic capacity and the lower the corresponding resonant frequency. The acoustic capacity of the sound cavity 20 is independent of its shape. Therefore, the shape of the sound cavity 20 and the cavity 2 is not limited. Considering the convenience of processing and assembly, it is preferable that their cross-sections are circular or rectangular (i.e., the overall shape is cylindrical or cuboid). In addition, the shapes of the sound inlet tube 1 and the sound outlet tube 3 are also not limited. For example, their cross-sectional shapes can be rectangular or circular. In Embodiment 1, the sound cavity 20 and the cavity 2 are both cuboid in shape, and the sound inlet tube 1 and the sound outlet tube 3 are both cylindrical.

[0059] In a preferred embodiment, the inlet pipe 1 and the outlet pipe 3 are connected to opposite sides of the cavity 2, so that sound waves can propagate from the outlet pipe 3 along the direction in which they enter the inlet pipe 1. This results in smoother sound propagation, reduced energy loss due to changes in direction, and higher efficiency. For example, Figure 3The cavity 2 shown is rectangular in shape and includes a first surface 2a and a second surface 2b arranged opposite each other. The sound inlet pipe 1 and the sound outlet pipe 3 are respectively connected to the first surface 2a and the second surface 2b. Furthermore, the sound inlet pipe 1 and the sound outlet pipe 3 are arranged coaxially to further improve the efficiency of sound wave transmission.

[0060] Furthermore, the acoustic impedance of the materials used for the inlet tube 1, cavity 2, and outlet tube 3 is much greater than that of air. Preferably, the acoustic impedance of these materials is more than 300 times that of air. The inlet tube 1 is preferably made of an elastic material, which, while forming an acoustic waveguide, also possesses a certain degree of deformability, increasing its flexibility and safety. Examples of materials used for the inlet tube 1 include rubber, silicone, or plastic. The cavity 2 is also preferably made of an elastic material, such as silicone or soft rubber, which is relatively soft and deformable. The outlet tube 3 is preferably made of a material with a higher hardness than the cavity 2. This prevents significant deformation under pressure that could block its outlet hole 30, while also maintaining the overall volume as much as possible while the cavity 2 deforms appropriately, ensuring acoustic performance. Preferably, the outlet tube 3 is made of plastic. Additionally, since the outlet surface 31 of the outlet tube 3 needs to contact the outside environment, choosing a plastic material for it ensures that its hardness is not excessive, making it safer and more comfortable. It is understood that the above materials are merely examples and are not limited to these.

[0061] The position of the sound outlet tube 3 relative to the sound cavity 20 is not limited. For example, in the first embodiment, the sound outlet tube 3 is completely disposed inside the cavity 2. (Refer to...) Figure 3 In this embodiment, the sound outlet surface 31 of the sound outlet tube 3 is flush with the second surface 2b of the cavity 2. While the tube 3 affects the volume of the sound cavity 20, the comfort and safety are better because the sound outlet tube 3 does not protrude outside the cavity 2. In the second embodiment, the sound outlet tube 3 is completely located outside the sound cavity 20. (Refer to...) Figure 4 The sound outlet tube 3 does not protrude into the sound cavity 20, thus having almost no impact on the volume of the sound cavity 20. In the third embodiment, refer to... Figure 5 The sound outlet tube 3 is partially located inside the acoustic cavity 20 and partially located outside the cavity 2. Since the volume of the sound outlet tube 3 inside the acoustic cavity 20 affects the volume of the acoustic cavity 20, the resonant frequency of the low-frequency sound wave radiation enhancement structure can also be controlled by adjusting the length of the sound outlet tube 3 extending into the acoustic cavity 20.

[0062] It is understandable that the inlet pipe 1, cavity 2 and outlet pipe 3 can be integrally formed or they can be made of multiple parts connected together.

[0063] Example 2

[0064] like Figures 6 to 8As shown, in this embodiment, both the inlet pipe 1 and the outlet pipe 3 are rectangular tubes, and the cavity 2 and the acoustic cavity 20 are cuboid in shape. The two relatively parallel first sidewalls 10 of the inlet pipe 1 are flush with the two relatively parallel second sidewalls 23 of the cavity 2. The two sidewalls of the outlet pipe 2 borrow from the second sidewalls 23 of the cavity 2. Specifically, the relatively parallel top plate 32 and bottom plate 33 of the outlet pipe 3 are connected to the relatively parallel second sidewalls 23 of the cavity 2.

[0065] Figure 9 and Figure 10 As a first example of a low-frequency sound wave radiation enhancement structure, the figure shows the specific dimensional parameters of the main parts of the low-frequency sound wave radiation enhancement structure. Specifically, the length of cavity 2 is 400mm, the width is 200mm, and the height is 200mm. The thickness of the hole in the inlet pipe 1 is 35mm, the thickness of the hole in the outlet pipe 3 is 60mm, and the length extending into the sound cavity 20 is 50mm. The wall thickness of inlet pipe 1, cavity 2, and outlet pipe 3 is 5mm.

[0066] like Figure 11 As shown, Figure 11 The diagram shows the low-frequency sound wave radiation enhancement structure of the first example and the frequency response curves of the comparative example, where the loudspeaker is only installed with... Figure 10 The structure of the sound inlet tube 1 shown is closer to the actual sound output of the loudspeaker because the sound inlet tube 1 is equivalent to the sound transmission tube described in the background art. Curve 1 (solid line) in the figure represents the loudspeaker with only [the following text is missing: "installed"] Figure 10 The first example shows the frequency response curve (i.e., the comparative frequency response curve) measured 1m away from the outlet of the sound tube 3 without the cavity 2 and the outlet tube 3 installed. The second example shows the frequency response curve measured 1m away from the outlet of the sound tube 3 after the low-frequency sound wave radiation enhancement structure of the first example is installed. As can be seen from the figure, after adding the low-frequency sound wave radiation enhancement structure of the first example, the sound pressure in the low-frequency range of 80Hz~160Hz is significantly improved (>6 dB).

[0067] Example 3

[0068] refer to Figures 12 to 15 Similar to Example 2, in Example 3, the inlet pipe 1 and outlet pipe 3 of the low-frequency sound wave radiation enhancement structure are both rectangular tubes, the cavity 2 is roughly cuboid in shape, the two relatively parallel first sidewalls 10 of the inlet pipe 1 are flush with the two second sidewalls 23 of the cavity 2, the outlet pipe 2 is located inside the cavity 2 and its two sidewalls borrow from the second sidewalls 23 of the cavity 2.

[0069] In this embodiment, the low-frequency sound wave radiation enhancement structure includes two or more relatively independent acoustic cavities 20. The number shown in the figure is three, and each acoustic cavity 20 is provided with a sound outlet tube 3 that communicates with it.

[0070] The cavity 2 also includes a front cavity 21 communicating with the sound inlet pipe 1 and a sound channel 22 connecting the sound cavity 20 and the front cavity 21. Each sound cavity 20 is provided with a sound channel 22 communicating with it. The front cavity 21 and the sound channel 22 are used to transmit the sound waves from the sound inlet pipe 1 into the three sound cavities 20. Preferably, the cross-sectional area of ​​the sound channel 22 is smaller than the cross-sectional area of ​​the sound cavity 20 directly communicating with it. In this embodiment, the width of the sound channel 22 is the same as the width of the sound cavity 20, and its cross-sectional area is reduced by reducing the thickness of the sound channel 22.

[0071] The two adjacent acoustic cavities 20 and the two adjacent acoustic channels 22 are separated by an isolator set in the cavity 2. The isolator can be plate-shaped or block-shaped. By adjusting the position, thickness and distance between two adjacent isolators, the volume of the acoustic cavity 20, acoustic channel 22 and front cavity 21 can be changed.

[0072] In a preferred embodiment, the isolating element includes a plate 24 for separating two adjacent acoustic cavities 20 and a block 25 for separating the front cavity 21 and the acoustic cavity 20. In the figure, the plate 24 and the block 25 are perpendicular. The width B1 of the block 25 is set to be greater than the thickness B2 of the plate 24 to reduce the mutual influence between the front cavity 21 and the acoustic cavity 20 and improve the acoustic effect. In the figure, the acoustic channel 22 is located between the blocks 25 of two adjacent isolating elements or formed between the blocks 25 and the outer shell of the cavity 2.

[0073] In this embodiment, since multiple acoustic cavities 20 are provided, sound waves can resonate within the multiple acoustic cavities 20 and emit sound through the sound outlet tube 3. By controlling the size of the acoustic cavities 20 and parameters such as the length and cross-sectional area of ​​the sound outlet tube 3, the resonant frequency of each acoustic cavity 20 can be changed, thereby increasing the sound pressure level in different frequency bands and enhancing the sound pressure level of the sound waves in a wider low-frequency range. Specifically, refer to... Figure 11 , Figure 11 In the curve 2, the sound pressure level is significantly improved in the 80 Hz~160 Hz frequency band, but the sound pressure level decreases again in the 200~400 Hz range. By adding a sound cavity 20, the sound pressure level in the 200~400 Hz range can be enhanced.

[0074] Figure 16 and Figure 17A second example of a low-frequency sound wave radiation enhancement structure is shown. The specific dimensions of each part of the low-frequency sound wave radiation enhancement structure in the second example are shown in the figure. For ease of description, the three acoustic cavities 20 from top to bottom in the figure are referred to as the first acoustic cavity 20a, the second acoustic cavity 20b, and the third acoustic cavity 20c, respectively. The corresponding acoustic channels 22 and the sound outlet tubes 3 are referred to as the first acoustic channel 22a, the second acoustic channel 22b, the third acoustic channel 22c, the first sound outlet tube 3a, the second sound outlet tube 3b, and the third sound outlet tube 3c, respectively. Among them, the second acoustic channel 22b has the largest thickness, while the first acoustic channel 20a and the second acoustic channel 20c have the same thickness. The second acoustic cavity 20b has the largest thickness, while the first acoustic cavity 20a and the third acoustic cavity 20c have the same thickness. The third acoustic cavity 20c has the shortest length, while the first acoustic cavity 20a and the second acoustic cavity 20b have the same length. Thus, the volumes of the three acoustic cavities 20, from largest to smallest, are the second acoustic cavity 20b, the first acoustic cavity 20a, and the third acoustic cavity 20c. The thickness of the sound outlet hole of the third sound outlet tube 3c is the smallest, while the thickness of the sound outlet holes of the first sound outlet tube 3a and the second sound outlet tube 3b is the same.

[0075] Figure 18 The diagram shows the low-frequency sound wave radiation enhancement structure of the second example and the frequency response curve of the comparative example (the comparative example is the same as the comparative example in Example 2). In the diagram, curve 3 represents the frequency response curve of the speaker when only installed... Figure 17 The frequency response curve (i.e., the comparative frequency response curve) is measured at a distance of 1m from the outlet of the sound tube 3 when the sound inlet tube 1 is installed without cavity 2 and sound outlet tube 3. Curve 4 is the frequency response curve measured at a distance of 1m from the outlet of the sound tube 3 after the same loudspeaker is equipped with the low-frequency sound wave radiation enhancement structure of the second example. The three acoustic cavities 20 of the low-frequency sound wave radiation enhancement structure of the second example are connected in parallel, each controlling a different frequency resonance. The resonance frequency of the first acoustic cavity 20a is about 200 Hz, the resonance frequency of the second acoustic cavity 20b is about 130 Hz, and the resonance frequency of the third acoustic cavity 20c is about 350 Hz. Figure 18 As can be seen, the sound pressure level is significantly improved from 100Hz to 500Hz, with the resonance peak near 500Hz brought about by the higher-order resonance mode of the second acoustic cavity 20b. Clearly, by setting up multiple acoustic cavities 20, multiple frequency ranges in the low-frequency band achieve a higher sound pressure level than the comparative model, resulting in better low-frequency performance.

[0076] Figure 18 In the sound, the resonance peak produced by the first acoustic cavity 20a is not obvious. This is because the resonance is located in the valley created by the resonance of the second acoustic cavity 20b, indicating coupling between the first and second acoustic cavities 20a and 20b. Although it cannot produce a distinct resonance peak, it still has a significant effect on improving the overall sound pressure level. (Reference) Figure 20 , Figure 20 Compared to Figure 18A third example frequency response curve—curve 5—has been added. The structure of the third example is examined. Figure 19 Compared to the second example, it omits the first acoustic cavity 20a, possessing only the second acoustic cavity 20b and the third acoustic cavity 20c. The dimensions of each part in the third example are identical to the corresponding dimensions of the parts in the second example. Figure 20 As can be seen, the sound pressure level of curve 4 is greater than that of curve 5 in almost the entire frequency range. This shows that the first acoustic cavity 20a has a significant effect on improving the overall sound pressure level.

[0077] It is understandable that the specific dimensional parameters in the examples above are only examples and can be changed as needed, such as reducing the overall size due to the available space at the installation location.

[0078] The present invention also proposes a sound-generating device, which includes a loudspeaker and a low-frequency sound wave radiation enhancement structure. The loudspeaker has a sound-emitting end, and a sound inlet tube 1 is connected to the sound-emitting end to guide the sound waves emitted by the loudspeaker. Preferably, the sound inlet tube 1 completely covers the sound-emitting surface of the loudspeaker, and the connection between the sound inlet tube 1 and the loudspeaker is in tight contact or sealed by a sealing element to reduce sound wave leakage and improve sound transmission efficiency.

[0079] The above are merely specific embodiments of the present invention, and any improvements made based on the concept of the present invention shall be considered within the scope of protection of the present invention.

Claims

1. A low-frequency acoustic radiation enhancement structure, characterized in that, include: The sound inlet tube (1) is used to connect to the sound-emitting surface of the sound source. The sound inlet tube (1) completely covers the sound-emitting surface to receive the sound emitted by the sound source. Cavity (2), including acoustic cavity (20), the sound inlet pipe (1) is connected to and communicates with the acoustic cavity (20); and, The sound outlet tube (3) is connected to the cavity (2) and communicates with the acoustic cavity (20). The cross-sectional areas of the sound outlet tube (3) and the sound inlet tube (1) are both smaller than the cross-sectional area of ​​the acoustic cavity (20). After the sound from the sound source enters the cavity (2) through the sound inlet tube (1), it resonates in the acoustic cavity (20) of the cavity (2) and then is transmitted out through the sound outlet tube (3). The dimensions of the sound outlet tube (3) and the acoustic cavity (20) are both smaller than one-tenth of the wavelength of the sound wave corresponding to the resonant frequency of the low-frequency sound wave radiation enhancement structure. The inlet pipe (1) and the outlet pipe (3) are connected to opposite sides of the cavity (2). The inlet pipe (1) and the sound source are located on the same side of the cavity (2). The sound emitted by the sound source can be transmitted from the outlet pipe (3) along the direction of entering the inlet pipe (1).

2. The low-frequency acoustic radiation enhancement structure as described in claim 1, characterized in that, The inlet pipe (1) and the outlet pipe (3) are arranged on the same axis.

3. The low-frequency acoustic radiation enhancement structure as described in claim 1, characterized in that, The acoustic impedance of the materials of the inlet pipe (1), cavity (2) and outlet pipe (3) is greater than or equal to 300 times the air acoustic impedance.

4. The low-frequency acoustic radiation enhancement structure as described in claim 3, characterized in that, The cavity (2) is made of an elastic material, and the material hardness of the sound outlet tube (3) is greater than that of the cavity (2).

5. The low-frequency acoustic radiation enhancement structure as described in claim 1, characterized in that, The sound outlet tube (3) is located inside the cavity (2), or the sound outlet tube (3) is located outside the sound cavity (20), or the sound outlet tube (3) is partially located inside the sound cavity (20) and partially located outside the cavity (2).

6. The low-frequency acoustic radiation enhancement structure according to any one of claims 1 to 5, characterized in that, The cavity (2) includes two or more acoustic cavities (20), and each acoustic cavity (20) is provided with a corresponding sound outlet tube (3).

7. The low-frequency acoustic radiation enhancement structure as described in claim 6, characterized in that, The resonant frequencies of each acoustic cavity (20) are different; At least two acoustic cavities (20) have different volumes, or at least two sound outlet tubes (3) have different cross-sectional areas or lengths.

8. The low-frequency acoustic radiation enhancement structure as described in claim 6, characterized in that, The cavity (2) includes a front cavity (21) communicating with the sound inlet tube (1) and a sound channel (22) connecting the sound cavity (20) and the front cavity (21).

9. The low-frequency acoustic radiation enhancement structure as described in claim 8, characterized in that, The cavity (2) also includes a plate (24) and a block (25) connected to each other. The plate (24) is used to separate the acoustic cavity (20), and the block (25) is used to separate the front cavity (21) and the acoustic cavity (20). The width of the block (25) is greater than the thickness of the plate (24).

10. A sound-generating device, characterized in that, include: speaker; as well as, The low-frequency sound wave radiation enhancement structure as described in any one of claims 1 to 9, wherein the loudspeaker is connected to the sound inlet tube (1).

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