CN108471577B

CN108471577B - Acoustic device

Info

Publication number: CN108471577B
Application number: CN201810263893.7A
Authority: CN
Inventors: 柯海力
Original assignee: Hansong Nanjing Technology Co ltd
Current assignee: Hansang Nanjing Technology Co ltd
Priority date: 2018-03-28
Filing date: 2018-03-28
Publication date: 2021-05-18
Anticipated expiration: 2038-03-28
Also published as: CN108471577A

Abstract

The invention discloses an acoustic device, comprising: a first compression driver comprising a first diaphragm that vibrates to produce a first sound wave; the annular waveguide is arranged opposite to the first compression driver, a first compression cavity is formed between the annular waveguide and the first diaphragm, and the width of the first compression cavity is close to one quarter of the wavelength corresponding to the highest-frequency sound wave generated by the vibration of the first diaphragm. The acoustic device can realize that sound is uniformly diffused along 360 degrees on a plane vertical to the driving direction of the compression driver, improves the sound production range of the acoustic device, and realizes omnidirectional sound production.

Description

Acoustic device

Technical Field

The invention relates to the technical field of acoustics, in particular to a loudspeaker.

Background

The loudspeaker is a common acoustic sound amplification device, can effectively realize sound reduction and playing, and can meet most of audio application scenes.

However, in some special use occasions, such as air defense warning, disaster prevention propaganda and the like, the sound amplifying device is required to have very good omnidirectional consistency, and the sound emitted by the loudspeaker in the prior art has specific directivity, so that the receiving range of the sound is greatly limited, and obviously, the sound amplifying device is not an ideal sound amplifying device.

Disclosure of Invention

Aiming at the defects in the prior art, the embodiment of the invention aims to provide the acoustic device, by coupling the compression driver with the annular waveguide, sound can be uniformly diffused on a plane perpendicular to the driving direction of the compression driver along 360 degrees, the sound production range of the acoustic device is improved, and omnidirectional sound production is realized.

To achieve these objects and other advantages in accordance with the purpose of the invention, the present invention provides an acoustic device comprising:

a first compression driver comprising a first diaphragm that vibrates to produce a first sound wave;

the annular waveguide is arranged opposite to the first compression driver, a first compression cavity is formed between the annular waveguide and the first diaphragm, and the width of the first compression cavity is close to one quarter of the wavelength corresponding to the highest-frequency sound wave generated by the vibration of the first diaphragm.

Preferably, the first diaphragm is a circular arc convex surface or a conical convex surface.

Preferably, a concave surface is arranged in the center of the annular waveguide, the shape of the concave surface is matched with that of the first diaphragm, and the first compression cavity is formed between the concave surface and the first diaphragm.

Preferably, the first compression driver is annular and the annular waveguide is coaxial with the first compression driver.

Preferably, a first sound wave generated by vibration of the first diaphragm propagates along the first compression chamber.

Preferably, the cross-sectional profile curve of the outer edge of the annular waveguide is an exponential curve.

Preferably, the first compression driver includes any one of a high frequency compression driver, a medium frequency compression driver, or a low frequency compression driver.

Preferably, the high frequency compression driver, the medium frequency compression driver and the low frequency compression driver correspond to the first compression cavities with different widths, respectively.

Preferably, the apparatus further comprises a second compression driver comprising a second diaphragm that vibrates to produce the second acoustic wave.

The second compression driver, the second diaphragm, the first compression driver and the first diaphragm are respectively arranged on two sides of the annular waveguide, and a second compression cavity is formed between the second diaphragm and the annular waveguide.

Preferably, the width of the second compression chamber is approximately one quarter of the wavelength corresponding to the highest-frequency sound wave generated by the vibration of the second diaphragm.

Drawings

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a cross-sectional view of an acoustic device according to an embodiment;

fig. 2 is a schematic diagram illustrating an operation principle of an acoustic device according to an embodiment;

fig. 3 is a cross-sectional view of an acoustic device according to another embodiment;

fig. 4 is a cross-sectional view of an acoustic device according to yet another embodiment;

FIG. 5 is a schematic sound propagation diagram obtained by finite element simulation analysis of an acoustic device according to an embodiment of the present invention;

FIG. 6 is a diagram illustrating the results of a measurement analysis of the output of an acoustic device according to one embodiment;

FIG. 7 is a graph of the sensitivity of an acoustic device according to one embodiment;

fig. 8 is a directivity index curve of an acoustic device according to an embodiment;

FIG. 9 is a diagram of an acoustic three-dimensional output balloon of an acoustic device according to one embodiment;

FIG. 10 is a frequency response curve of an acoustic device according to one embodiment;

fig. 11 is a frequency response curve of an acoustic apparatus after an equalizer is added according to an embodiment.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments.

It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures. In the drawings, the shape and size may be exaggerated for clarity, and the same reference numerals will be used throughout the drawings to designate the same or similar components. In the following description, terms such as center, thickness, height, length, front, back, rear, left, right, top, bottom, upper, lower, and the like are used based on the orientation or positional relationship shown in the drawings. In particular, "height" corresponds to the dimension from top to bottom, "width" corresponds to the dimension from left to right, and "depth" corresponds to the dimension from front to back. These relative terms are for convenience of description and are not generally intended to require a particular orientation. Terms concerning attachments, coupling and the like (e.g., "connected" and "attached") refer to a relationship wherein structures are secured or attached, either directly or indirectly, to one another through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.

Fig. 1 is a cross-sectional view of an acoustic device according to an embodiment of the present invention. The acoustic device includes: a first compression driver 106 and a ring waveguide.

The first compression driver 106 is disposed coaxially with the annular waveguide. The first compression driver 106 may be an electric, electrostatic, electromagnetic, piezoelectric, electro-ionic, or pneumatic compression driver, for example. The first compression driver 106 is a small diaphragm speaker that produces sound. The first compression driver 106 comprises a first diaphragm 103, the first diaphragm 103 being disposed at an end of the first compression driver 106 opposite the annular waveguide. The first diaphragm 103 may be a cone diaphragm, a pan bottom diaphragm, a hemispherical diaphragm, or the like. The first diaphragm 103 may be made of natural fibers (such as paper, wool, silk), metal, composite materials (such as fiber fabric plated metal), polymer synthetic fibers (such as plastic), wood fibers, or biological materials. Under the compression drive of the first compression driver 106, the first diaphragm 103 vibrates, generating a first sound wave. The first acoustic wave may propagate in a direction in which the first diaphragm 103 vibrates. The frequency of the first sound wave may be in any frequency band, for example, all audible sound waves. In some embodiments, the first acoustic wave has a frequency of 50Hz-18 KHz.

In some embodiments, the annular waveguide comprises a first annular waveguide 101. The first annular waveguide 101 is disposed opposite the first compression driver 106. A first compression chamber 108 is formed between the first annular waveguide 101 and the first diaphragm 103. A first acoustic wave generated by the vibration of the first diaphragm 103 is transmitted from the first compression chamber 108 and reflected by the curved surface R-1 at the lower end of the first annular waveguide 101, so that the first acoustic wave can propagate both toward 360 ° along a plane perpendicular to the axis b and in a direction perpendicular to the plane.

In other embodiments, the annular waveguide comprises a first annular waveguide 101 and a second annular waveguide 105. As shown in fig. 1, the second annular waveguide 105 is disposed opposite to the first annular waveguide 101, and a plurality of pillars 104 capable of supporting the first annular waveguide 101 are disposed between the second annular waveguide 105 and the first annular waveguide 101, so that the first annular waveguide 101 is spaced apart from the first diaphragm 103 by a specific distance, for example, 6 pillars 104 are uniformly distributed on the periphery of the second annular waveguide 105, and the 6 pillars 104 support the first annular waveguide 101, so that the first annular waveguide 101 is spaced apart from the first diaphragm 103 by 4 cm.

In some embodiments, an opening 107 is opened in the center of the second annular waveguide 105, and the first diaphragm 103 passes through the opening 107 and is opposite to the first annular waveguide 101. The first diaphragm 103 may be of any shape.

In some embodiments, the first diaphragm 103 is a circular arc convex surface. The center of the first annular waveguide 101 is provided with a concave surface 102 matched with the first diaphragm 103, and a first compression cavity 108 is formed between the concave surface 102 and the first diaphragm 103. The width a of the first compression chamber 108 may be a specific value.

In some embodiments, the width a may be two times, one half, one eighth, etc. of the wavelength corresponding to the highest frequency sound wave generated by the vibration of the first diaphragm 103. The corresponding wavelength of the highest frequency sound wave is equal to the ratio of the sound velocity (340m/s) to the highest frequency. For example, the highest frequency of the first sound wave generated by the vibration of the first diaphragm 103 is 4250Hz, and the width a may be one half of the wavelength corresponding to the highest frequency sound wave, that is, the width a is 0.04 m.

In some embodiments, the width a of the first compression chamber 108 is approximately one-quarter of the wavelength corresponding to the highest frequency acoustic wave generated by the vibration of the first diaphragm 103. The corresponding wavelength of the highest frequency sound wave is equal to the ratio of the sound velocity (340m/s) to the highest frequency. "close" as used herein means approximately or equal to the difference between the width a of the first compression chamber 108 and a quarter of the wavelength corresponding to the highest frequency sound wave is maintained within a certain error range. For example, the frequency of the highest frequency sound wave generated by the vibration of the first diaphragm 103 is 17000Hz, and the calculated highest frequency sound wave corresponds to a wavelength of 0.02m, a quarter of the wavelength is 0.005m (5mm), and the error range is ± 0.05mm, that is, the width a of the first compression cavity 108 is between 4.95mm and 5.05 mm.

By the compression driving of the first compression driver 106, the first acoustic wave generated by the vibration of the first diaphragm 103 can propagate along the first compression chamber 108 and propagate to 360 ° in a plane perpendicular to the annular waveguide axis b, thereby improving the sound emission range. The cross section of the outer edges of the first annular waveguide 101 and the second annular waveguide 105 can be a curve with any shape.

In some embodiments, the cross-sectional profile of the outer edges of the first and second

annular waveguides

101, 105 may be curved with different curvatures. For example, the cross-sectional profile curve of the outer edge of the first annular waveguide 101 is an exponential curve, so that after the sound wave is reflected by the outer end curved surface of the first annular waveguide 101, the sound wave can be diffused in the vertical direction while maintaining uniform propagation of the sound wave.

Fig. 2 is a schematic diagram illustrating an operation principle of an acoustic device according to an embodiment of the present invention. The first diaphragm 103 vibrates under the driving action of the first compression driver 106 and generates a first sound wave, and the distance from the center of the first diaphragm 103 to a sound receiving point is greater than 2 times of the geometric size of the first diaphragm 103, for example, the geometric size of the first diaphragm is 6cm, and the distance from the sound receiving point to the center of the first diaphragm is 20 cm. And the phases of the vibrations of the portions of the first diaphragm 103 are approximately the same, for example, the phases of the sound waves emitted from the portions of the first diaphragm 103 are within 5 °. The acoustic device may be regarded as a point sound source, and the first sound wave generated by the first diaphragm 103 is uniformly distributed on a spherical surface having the center of the first diaphragm 103 as a spherical center.

The first diaphragm 103 compresses air in the first compression chamber 108 when vibrating upwards, and a first sound wave is thus formed and forced out of the opening of the first compression chamber 108. The width a of the first compression chamber 108 is approximately one quarter of the wavelength corresponding to the highest frequency sound wave generated by the vibration of the first diaphragm 103, so that the sound intensity transmitted from the first compression chamber 108 is greater. Specifically, the sound wave transmitted from the first compression cavity 108 is equal to the sum of the first sound wave generated by the vibration of the first diaphragm 103 and the reflected wave formed after being reflected by the concave surface 102, since the sound wave has half-wave loss during reflection, and the width a of the first compression cavity 108 is close to one fourth of the wavelength corresponding to the highest-frequency sound wave generated by the vibration of the first diaphragm 103, the propagation distance from the sound wave transmitted to the reflected wave is half wavelength, and then the reflected half-wave loss is added, the reflected wave is different from the first sound wave generated by the vibration of the first diaphragm by exactly one wavelength, that is, the phase of the reflected wave is the same as that of the first sound wave, so that the sound pressure of the sound wave formed after the superposition is larger, that is, the intensity of the sound wave transmitted from the first compression cavity 108 is larger.

The lines with arrows in fig. 2 are used to indicate the propagation paths of the acoustic waves. As can be seen, the first sound wave propagates circumferentially from the opening of the first compression chamber 108 into the gap 200, so that the first sound wave can propagate 360 ° along a horizontal plane perpendicular to the axis of the ring waveguide. And part of the first sound wave which propagates upwards contacts with the lower end curved surface R-1 of the first annular waveguide 101 and is reflected by the lower end curved surface R-1 of the first annular waveguide 101, part of the first sound wave which propagates downwards contacts with the upper end curved surface R-2 of the second annular waveguide 105 and is reflected by the upper end curved surface R-2 of the second annular waveguide 105, because the cross-sectional profile curve of the outer edge of the first annular waveguide 101 is an exponential curve and the cross-sectional profile of the outer edge of the second annular waveguide 105 is also a curve, the first sound wave is diffused to a certain extent in the vertical direction after being reflected, can be uniformly propagated in the area vertical to the horizontal plane, and the propagation range is further expanded.

Fig. 3 is a cross-sectional view of an acoustic device according to another embodiment of the present invention. The acoustic device includes: a first compression driver 106 and a ring waveguide. The first compression driver 106 is disposed coaxially with the annular waveguide. The first compression driver 106 may be an electric, electrostatic, electromagnetic, piezoelectric, electro-ionic, or pneumatic compression driver, for example. The first compression driver 106 includes a first diaphragm 103, and the first diaphragm 103 may be a cone diaphragm, a pan bottom diaphragm, a hemispherical diaphragm, or the like. The first diaphragm 103 may be made of natural fibers (such as paper, wool, silk), metal, composite materials (such as fiber fabric plated metal), polymer synthetic fibers (such as plastic), wood fibers, or biological materials. The first diaphragm 103 vibrates to generate a first sound wave. The frequency of the first sound wave may be in any frequency band, for example, all audible sound waves. In some embodiments, the frequency of the first sound wave generated by the vibration of the first diaphragm 103 is 50Hz-18 KHz.

The annular waveguide comprises a first annular waveguide 101, a first compression cavity 108 is formed between the first annular waveguide 101 and the first diaphragm 103, and a first sound wave generated by the vibration of the first diaphragm 103 is transmitted out of the first compression cavity 108 and reflected by a lower curved surface R-1 of the first annular waveguide 101, so that the first sound wave can propagate along a direction perpendicular to a plane to 360 ° and along the direction perpendicular to the plane.

In some embodiments, the annular waveguide includes a first annular waveguide 101 and a second annular waveguide 105, wherein the second annular waveguide 105 is disposed opposite to the first annular waveguide 101, and a plurality of pillars 104 capable of supporting the first annular waveguide 101 are disposed between the first annular waveguide 101 and the second annular waveguide 105, so that the first annular waveguide 101 is spaced apart from the first diaphragm 103 by a specific distance. For example, 6 vertical columns 104 are uniformly spaced between the first annular waveguide 101 and the second annular waveguide 105, so that the first annular waveguide 101 and the first diaphragm 103 are spaced by 2 cm. The first diaphragm 103 may have any shape.

In some embodiments, the first diaphragm 103 is a conical convex surface. The center of the first annular waveguide 101 is provided with a concave surface 102 matched with the first diaphragm 103, a first compression cavity 108 is formed between the concave surface 102 and the first diaphragm 103, and through the compression driving of a first compression driver 106, a first sound wave generated by the vibration of the first diaphragm 103 is transmitted along the first compression cavity 108 and is diffused to 360 degrees on a plane perpendicular to the axis b of the annular waveguide, so that the sound production range is improved, and under the reflection of an upper end curved surface R-2 of the second annular waveguide 105 and a lower end curved surface R-1 of the first annular waveguide 101, the first sound wave can be uniformly diffused along the direction perpendicular to the plane.

Fig. 4 is a cross-sectional view of an acoustic device according to still another embodiment. The acoustic device includes a first compression driver 106, a second compression driver 110, and a ring waveguide 109.

The first compression driver 106 includes a first diaphragm 103, the second compression driver 110 includes a second diaphragm 111, wherein the first compression driver 106, the first diaphragm 103, the second compression driver 110, and the second diaphragm 111 are respectively disposed on two sides of the annular waveguide 109, and the first compression driver 106 and the second compression driver 110 may be electric, electrostatic, electromagnetic, piezoelectric, ionic, or pneumatic compression drivers, etc. The first diaphragm 103 may be a cone diaphragm, a pan bottom diaphragm, a hemispherical diaphragm, or the like. The first diaphragm 103 and the second diaphragm 111 may be made of natural fibers (such as paper, wool, silk), metal, composite materials (such as fiber fabric plated metal), polymer synthetic fibers (such as plastic), wood fibers or biological materials. The first diaphragm 103 and the second diaphragm 111 may have any shape.

In some embodiments, the first diaphragm 103 and the second diaphragm 111 are circular arc convex surfaces. A first compression cavity 108 is formed between the annular waveguide 109 and the first diaphragm 103, when the first diaphragm 103 vibrates upwards, the first diaphragm 103 compresses air in the first compression cavity 108, a first sound wave is formed and propagates outwards from an opening of the first compression cavity 108, and is reflected by an upper end curved surface R-3 of the annular waveguide 109, so that the sound wave can be uniformly diffused to a plane 360 degrees and a direction perpendicular to the plane, a second compression cavity 112 is formed between the annular waveguide 109 and the second diaphragm 111, the second diaphragm 111 vibrates to generate a second sound wave, and the generation and propagation principle of the second sound wave is the same as that of the first sound wave. The widths of the first compression chamber 108 and the second compression chamber 112 may be a specific value.

In some embodiments, the width of the first compression chamber 108 and the width of the second compression chamber 112 are equal to two times, one half, one eighth, and so on of the wavelength corresponding to the highest frequency sound wave generated by the vibration of the corresponding first diaphragm 103 and second diaphragm 111, respectively. The corresponding wavelength of the highest frequency sound wave is equal to the ratio of the sound velocity (340m/s) to the highest frequency. For example, the frequency of the highest frequency sound wave generated by the vibration of the first diaphragm 103 is 5000Hz, and the width of the first compression cavity 108 is one half of the wavelength corresponding to the highest frequency sound wave, that is, the width of the first compression cavity 108 is 0.034 m. For another example, the frequency of the highest-frequency sound wave generated by the vibration of the second diaphragm 111 is 2000Hz, and the width of the second compression cavity 112 is one half of the wavelength corresponding to the highest-frequency sound wave, that is, the width of the second compression cavity 112 is 0.085 m.

In some embodiments, the width of the first compression chamber 108 is approximately one-fourth of the wavelength corresponding to the highest frequency sound wave generated by the vibration of the first diaphragm 103, and the width of the second compression chamber 112 is approximately one-fourth of the wavelength corresponding to the highest frequency sound wave generated by the vibration of the second diaphragm 111. The corresponding wavelength of the highest frequency sound wave is equal to the ratio of the sound velocity (340m/s) to the highest frequency. "close" as used herein means approximately equal to, i.e., the difference between the width of the first compression chamber 108 and the width of the second compression chamber 112 and a quarter of the wavelength corresponding to the highest frequency sound wave generated by the vibration of the first diaphragm 103 and the second diaphragm 111, respectively, is maintained within a certain error range. For example, the frequency of the highest frequency sound wave generated by the vibration of the first diaphragm 103 is 5000Hz, the corresponding quarter of the wavelength of the highest frequency sound wave is 0.0017m (1.7mm), the error range is ± 0.02mm, and the width of the first compression cavity 108 is between 1.68mm and 1.72 mm. For another example, the frequency of the highest frequency sound wave generated by the vibration of the second diaphragm 111 is 2000Hz, one quarter of the wavelength corresponding to the highest frequency sound wave is 0.00425m (4.25mm), the error range is ± 0.03mm, and the width of the second compression cavity 112 is between 4.22mm and 4.28 mm.

A reflective cavity 113 is further formed between the annular waveguide 109 and the second compression driver 110, and the reflective cavity 113 is disposed around the second compression cavity 112. When the second diaphragm 111 vibrates upwards, the second diaphragm 111 compresses air in the second compression cavity 112, a second sound wave is formed and propagates from the opening of the second compression cavity 112 to the reflection cavity 113, the second sound wave reaches the reflection cavity 113, enters the gap 400 formed between the annular waveguide 109 and the second compression driver 110 through multiple reflections of the upper surface of the second compression driver 110 and the lower surface of the annular waveguide 109, and further propagates through the lower end curved surface R-4 of the annular waveguide 109 by reflection, so that the second sound wave can propagate to 360 ° on a plane perpendicular to the axis of the annular waveguide 109 and can also uniformly propagate along the direction perpendicular to the plane. The first compression driver 106-3 and the second compression driver 110 may be any one of a high frequency compression driver, a medium frequency compression driver, or a low frequency compression driver. The width of the first compression chamber 108 or the second compression chamber 112 is changed accordingly for different frequency compression drivers.

The relevant acoustic properties of the acoustic device can be obtained by performing finite element simulation analysis on the device. Fig. 5 is a schematic sound propagation diagram obtained by finite element simulation analysis of an acoustic device according to an embodiment. As can be seen from the figure, the results of finite element simulation of the acoustic device show that the acoustic wave emerging from the compression chamber opening is a spherical wave. As shown, the

curves

510, 520, 530 and 540 all represent wave fronts of sound waves, the

curves

510, 520, 530 and 540 are arc-shaped and parallel to each other, which indicates that along the propagation direction of the sound waves, the wave fronts of the sound waves are spherical waves parallel to each other, and the sound pressures in all directions of the acoustic device are the same, thereby indicating that the sound emitted by the acoustic device is non-directional, has no phase difference and can be uniformly propagated.

Fig. 6 is a schematic diagram showing the result of measurement and analysis of the output of an acoustic device according to an embodiment. Curve 610 is a listening window curve for the acoustic device that is equal to the mean of the axial frequency response of the acoustic device, which in some embodiments represents the frequency response at 10 ° vertically and 10 °, 20 ° and 30 ° horizontally. Curve 620 is the acoustic power curve of the acoustic device, which is equal to the sum of the acoustic power radiated by the acoustic device in all directions, and it can be seen from the figure that curve 610 and curve 620 tend to coincide, and it follows that the axial frequency response of the acoustic device and the frequency response in all directions are nearly the same, and the acoustic device is nearly in a non-directional sound production mode. In the figure, a curve 630 is a directivity index curve of the acoustic device, the directivity index represents the difference between an axial frequency response curve 610 and an acoustic power curve 620, and it can be seen that the directivity index curve 630 approaches a straight line, so that the acoustic device realizes an almost flat directivity index and displays an omnidirectional sound field.

As shown in fig. 7, a sensitivity curve of an acoustic device according to an embodiment is provided. The abscissa of the graph represents frequency and the ordinate represents sound pressure level, and the sensitivity of the acoustic device corresponds to the average frequency response at an input signal of 2.83V. The sensitivity of the acoustic device is measured in order to obtain the output of the acoustic device at a standard input voltage. Curve 710 is the axial frequency response of the acoustic device at an input signal of 2.83V and curve 720 is the off-axis frequency response of the acoustic device at an input voltage of 2.83V. As can be seen in FIG. 7, at frequencies below 10³At Hz, curves 710 and 720 almost completely coincide, at frequencies greater than 10³At Hz, curves 710 and 720 are slightly different but close to coincident, as can be seen whenFrequency below 10³At Hz, the sound pressure output by the acoustic device in all directions is almost the same, and the frequency is more than 10³At Hz, the output sound pressures of the acoustic device in all directions are slightly different, but approximately the same.

Fig. 8 is a directivity index curve of an acoustic device according to an embodiment, where the abscissa in fig. 8 represents frequency and the ordinate represents directivity index. The directivity index represents the difference between the axial frequency response and the off-axis frequency response of the acoustic device. The directivity index curve in fig. 8 can be obtained from the curve 710 and the curve 720 in fig. 7. As can be seen from fig. 8, at frequencies below 10³In Hz, the directivity index curve of the acoustic device is a straight line, the directivity index is 0, and the frequency is more than 10³In Hz, the directivity index curve of the acoustic device is a broken line with slight fluctuation, the broken line fluctuates at the directivity index of 0, and the directivity index tends to be 0. It follows that the axial and off-axis frequency responses of the acoustic device are almost identical, i.e. the acoustic device outputs sound pressures in all directions. The directivity index is an important parameter for describing the directivity characteristics of an acoustic device, and indicates the magnitude of the sound pressure level of a directional sound source increased over a non-directional sound source at the same radiation distance between the directional sound source and the non-directional (omni-directional radiation) sound source. The directivity index of the acoustic device tends to 0, which indicates that the acoustic device can be equivalent to a non-directional sound source, that is, the sound emitted by the acoustic device is non-directional and can realize omnidirectional sounding.

Fig. 9 is a diagram of an acoustic three-dimensional output balloon of an acoustic device according to an embodiment. Fig. 910, 920, 930, 940, and 950 show the acoustic output at a balloon radius of 3m when the acoustic device operates at 1kHz, 2kHz, 4kHz, 8kHz, and 16kHz, respectively, and it can be seen that the acoustic device outputs sound having a sound pressure level of about 73dB at an operating frequency of 1 kHz. At an operating frequency of 2kHz, the sound pressure level of the sound output by the acoustic device is approximately 70 dB. At an operating frequency of 4kHz, the sound pressure level of the sound output by the acoustic device is approximately 68 dB. At an operating frequency of 8kHz, the sound pressure level of the sound output by the acoustic device is approximately 66 dB. At an operating frequency of 16kHz, the sound pressure level of the sound output by the acoustic device is approximately 64 dB. Therefore, the sound pressure of the acoustic device does not change greatly along with the change of the frequency, and the acoustic device can keep a stable working state under different working frequencies.

By targeting the radiated acoustic power of the acoustic device for equalization, a flat frequency response can be obtained from any direction of the acoustic device. In order to flatten the high frequency characteristics of the acoustic device, an equalizer is added in front of the diaphragm of the acoustic device, and in some embodiments, a recursive Filter (IIR Filter) is used as the equalizer. Fig. 10 shows the frequency response curves of the acoustic device and the equalizer. Curve 1010 is the frequency response curve of the acoustic device, and curve 1020 is the frequency response curve of the recursive Filter (IIR Filter), and it can be seen from the figure that, in the case of no equalizer, the acoustic device has a sharp front d near the upper frequency limit and a valley c at a lower frequency, and the frequency response curve of the acoustic device fluctuates greatly, especially in the high frequency region. Fig. 11 is a frequency response curve of an acoustic device after an equalizer is added. The equalizer can compensate the defects of the loudspeaker and the sound field by adjusting the electric signals with various frequencies, and the frequency response curve of the acoustic device obtained by adding a recursive Filter (IIR Filter) as the equalizer is smoother, especially when the frequency is more than 10³At Hz, the curve varies within 4dB, so that the acoustic device can obtain brighter treble.

By adopting one or more of the above embodiments in combination, the embodiments of the present invention have at least the following advantages: the invention provides an acoustic device, which can realize the omnibearing and uniform diffusion of sound in the plane direction of 360 degrees and the direction vertical to the plane by coupling a compression driver with an annular waveguide, thereby improving the sound production range, and the produced sound has no directivity and good sound quality; aiming at compression drivers with different frequencies, the width of the compression cavity can be adjusted to adapt, so that the acoustic device has a wide application range; the acoustic device is simply coupled by the compression driver and the annular waveguide, and has simple manufacturing process and low manufacturing cost.

While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the embodiments, which are fully applicable in all kinds of fields of application of the invention, and further modifications may readily be effected by those skilled in the art, so that the invention is not limited to the specific details without departing from the general concept defined by the claims and the scope of equivalents.

Claims

1. An acoustic device, comprising:

an annular waveguide disposed opposite the first compression driver and forming a first compression cavity with the first diaphragm,

the width of the first compression cavity is close to one fourth of the wavelength corresponding to the highest-frequency sound wave generated by the vibration of the first diaphragm;

the apparatus further includes a second compression driver including a second diaphragm that vibrates to produce a second acoustic wave;

a second compression cavity is formed between the second diaphragm and the annular waveguide; a third compression cavity is further arranged between the annular waveguide and the second compression driver so as to increase the reflection times of the sound waves between the annular waveguide and the second compression driver;

the second compression driver, the second diaphragm, the first compression driver and the first diaphragm are respectively arranged on two sides of the annular waveguide.

2. The acoustic apparatus of claim 1, wherein the first diaphragm is convex.

3. The acoustic device of claim 2, wherein the annular waveguide is centrally provided with a concave surface, the concave surface being shaped to match the first diaphragm, the concave surface and the first diaphragm defining the first compression chamber therebetween.

4. The acoustic apparatus of claim 1, wherein the first compression driver is annular and the annular waveguide is coaxial with the first compression driver.

5. The acoustic apparatus of claim 1, wherein a first acoustic wave generated by vibration of the first diaphragm propagates along the first compression chamber.

6. The acoustic apparatus of claim 1, wherein the cross-sectional profile of the outer edge of the annular waveguide is exponential.

7. The acoustic apparatus of claim 1, wherein the first compression driver comprises any one of a high frequency compression driver, a mid frequency compression driver, or a low frequency compression driver.

8. The acoustic apparatus of claim 7, wherein the high frequency compression driver, the mid frequency compression driver, and the low frequency compression driver each correspond to different widths of the first compression cavity.

9. The acoustic apparatus of claim 1, wherein the width of the second compression chamber is approximately one quarter of the wavelength corresponding to the highest frequency acoustic wave generated by vibration of the second diaphragm.