Sound amplification unit capable of controlling sound field range

Abstract

The utility model provides a sound amplification unit capable of controlling a sound field range. The sound amplification unit comprises a sound gathering cover and a linear sound source sound post arranged in the sound gathering cover. The line sound source sound columns comprise medium-high frequency sound columns and low-frequency sound columns which are arranged back to back, and the low-frequency sound columns face the opening direction of the sound gathering cover. The cross section of the sound gathering cover is in the shape of a first-order parabola or a second-order combined parabola. The sound amplification unit forms a sound field control system, realizes effective control of the diffusion range of sound waves, and can effectively reduce sound pollution and sound interference caused by sound leakage and sound staining.

Description

Technical Field

[0001] This utility model relates to a sound amplification device, and more particularly to a sound amplification unit with controllable sound field range. The sound amplification unit includes a sound-focusing enclosure and a linear sound source column disposed within the sound-focusing enclosure, constituting a sound field control system. This system effectively controls the diffusion range of sound waves, thereby effectively reducing sound leakage, sound coloration leading to sound pollution, and sound interference. Background Technology

[0002] Theoretically, point sound sources produce spherical waves, while line sound sources produce cylindrical waves, and their transmission characteristics are fundamentally different. For example... Figure 1 As shown, the wavefront generated by point sound source 2 is a concentric sphere, called a spherical wave. Imagine a spherical sound source in an infinitely uniform medium, whose surface rapidly expands and contracts, with each point on the surface vibrating in phase and amplitude. The wave radiated into the surrounding medium is a spherical wave. This sound wave is spherically symmetric, meaning the sound pressure level depends only on the distance from the center of the sphere. Any sound source of any shape, as long as its size is much smaller than the wavelength, can be considered a point source, radiating spherical waves. For spherical waves, the sound intensity at any distance from the source is inversely proportional to the square of the distance, the sound pressure is inversely proportional to the distance, and the phase difference between the sound pressure and the vibration velocity is inversely proportional to the ratio of the radius of the spherical wave to the wavelength.

[0003] like Figure 2 As shown, the wavefront generated by line sound source 4 is a coaxial cylindrical wave, called a cylindrical wave. A cylindrical wave is a wave whose wavefront is a coaxial cylindrical surface. Imagine an infinitely long uniform line sound source in an infinitely uniform medium; the wave it produces would be an ideal cylindrical sound wave. In a cylindrical sound wave, the sound pressure amplitude is uniformly distributed along the axial direction and inversely proportional to the square root of the distance from the axis along the radial direction. Its radial sound intensity is inversely proportional to the first power of the distance from the axis.

[0004] As can be seen from the above acoustic theory analysis, the acoustic characteristics of a line sound source composed of cylindrical waves are far superior to those of a traditional point sound source composed of spherical waves. Specifically, this is manifested in: 1. Transmission characteristics: twice the efficiency. 2. Good coupling characteristics: low distortion caused by interference. 3. Better directivity control (strong directivity in the vertical direction). Therefore, how to convert spherical waves into cylindrical waves has become the main research focus of researchers in this field.

[0005] Prior art, Chinese patent application CN202210427881.X, discloses an adjustable vertically directional loudspeaker column. This technology uses a series of coaxial cylindrical mid-to-high frequency speakers to form a line sound source loudspeaker column.

[0006] In practical applications of public address systems, there are many situations where precise and controllable amplification range is required to reduce interference between sound sources. For example, the zoned sound control needs of museums and exhibition halls, or square dancing venues, often result in noise pollution and disturbance disputes due to uncontrollable sound field range. Utility Model Content

[0007] The technical problem to be solved by this utility model is to provide a sound amplification unit with controllable sound field range. This sound amplification unit uses a combination of a sound-focusing enclosure and a line sound source column set inside the sound-focusing enclosure to achieve three-dimensional control of sound wave diffusion and realize precise control of the sound field range.

[0008] This invention provides a sound amplification unit with controllable sound field range, including a sound-focusing cover and a line sound source column disposed inside the sound-focusing cover.

[0009] As an improvement, the line sound source columns include mid-to-high frequency sound columns and low frequency sound columns arranged back to back, with the low frequency sound columns facing the opening of the sound-gathering enclosure.

[0010] As an improvement, the cross-section of the sound-focusing enclosure is a first-order parabola. The acoustic center point of the mid-to-high frequency sound column is at the focus of the first-order parabola. The opening width of the first-order parabola is equal to the wavelength corresponding to the mid-to-low frequency crossover frequency. The first-order parabola extends along the axis of the line sound source sound column to form a first-order parabolic surface, which constitutes the inner surface of the sound-focusing enclosure.

[0011] Furthermore, the cross-section of the sound-focusing enclosure presents a second-order combined parabola. The acoustic center of the mid-to-high frequency sound column is at the focus of the first-order parabola. The opening width of the first-order parabola is equal to the wavelength corresponding to the mid-to-low frequency crossover frequency. The acoustic center of the low-frequency sound column is at the focus of the second-order parabola. The opening width of the second-order parabola is equal to the wavelength corresponding to the lower limit of the controllable frequency of the low-frequency sound column. The first-order parabola and the second-order parabola intersect at the intersection point. The second-order combined parabola is composed of the first-order parabola before the intersection point and the second-order parabola after the intersection point. The second-order combined parabola extends along the axis of the line sound source sound column to form a second-order combined parabolic surface. The second-order combined parabolic surface constitutes the inner surface of the sound-focusing enclosure.

[0012] The beneficial effects of this utility model compared with the prior art are as follows: (1) By utilizing the linear sound source column, sound wave diffusion control along the axis of the linear sound source column is achieved. As the length of the column axis increases, the lower limit of the controllable frequency will decrease. (2) By utilizing the sound focusing effect of the sound focusing cover, sound wave control in the direction of the opening of the sound focusing cover is achieved. The diffusion control of mid-to-high frequency sound waves is achieved through the first-order parabolic surface, and the diffusion control of low frequency sound waves is achieved through the second-order parabolic surface. (3) By utilizing the sound reflection effect of the sound focusing cover, sound wave diffusion control in the direction of the axis of the second-order combined parabola is achieved. Finally, the sound pressure difference between the inner and outer sound fields of the sound focusing cover can be ≥25dB. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a point sound source and a spherical wave.

[0014] Figure 2 This is a schematic diagram of a line sound source and a cylindrical wave.

[0015] Figure 3A and Figure 3B This is a schematic diagram of the linear sound source column structure in one embodiment of the present invention.

[0016] Figure 4 This is a schematic diagram of the cross-sectional structure of the sound amplification unit in one embodiment of the present invention.

[0017] Figure 5 This is a test curve of the sound pressure field inside and outside the sound-concentrating cover according to an embodiment of this utility model. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] like Figure 1 The diagram illustrates a point sound source and a spherical wave. Point sound source 2 produces a wavefront that is a concentric sphere, referred to as a spherical wave. Imagine a spherical sound source in an infinitely uniform medium. Its surface rapidly expands and contracts, and all points on the surface vibrate with the same phase and amplitude. The wave radiated into the surrounding medium is a spherical wave. This type of sound wave is spherically symmetric, meaning the sound pressure level depends only on the distance from the center of the sphere. Any sound source of any shape, as long as its size is much smaller than the wavelength, can be considered a point sound source, radiating spherical waves. For spherical waves, the sound intensity at any distance from the sound source is inversely proportional to the square of the distance. As shown in the diagram, when the distance from the sound source increases from R to R2 (twice the distance of R), the area of ​​the wavefront increases from A to 4A, and the sound intensity decreases to 1 / 4.

[0020] like Figure 2 The diagram illustrates a line sound source and a cylindrical wave. The line sound source 4 generates a wave whose wavefront is a coaxial cylindrical surface, referred to as a cylindrical wave. A cylindrical wave is a wave whose wavefront is a coaxial cylindrical surface. Imagine an infinitely long, uniform line sound source in an infinitely uniform medium; the wave it produces would be an ideal cylindrical sound wave. In a cylindrical sound wave, the sound pressure amplitude is uniformly distributed along the axial direction and inversely proportional to the square root of the distance from the axis along the radial direction. Its radial sound intensity is inversely proportional to the first power of the distance from the axis. As shown in the diagram, when the sound source distance increases from R to R2 (twice the distance of R), the area of ​​the wavefront increases from A to 2A, and the sound intensity decreases to 1 / 2.

[0021] like Figure 3A and Figure 3B A schematic diagram of a linear sound source column structure, in which... Figure 3A It is a side view. Figure 3BThis is a front view. In one embodiment of this utility model, a line source sound column 6 includes a mid-to-high frequency sound column 8 and a low-frequency sound column 10 arranged back-to-back, with the low-frequency sound column 10 facing the opening of the sound-gathering enclosure (not shown). The mid-to-high frequency sound column 8 consists of a row of six coaxial mid-to-high frequency horns 12, and the low-frequency sound column 10 consists of a row of four low-frequency horns 14. The axis 16 of the mid-to-high frequency horns 12 and the axis 18 of the low-frequency horns 14 are parallel to each other and are in the same plane as the axis 20 of the line source sound column 6, the mid-to-high frequency sound column 8, and the low-frequency sound column 10.

[0022] Figure 4 This is a cross-sectional structural diagram of the sound amplification unit in one embodiment of the present invention. The cross-section cuts across the axis of the length of the sound amplification unit 22, which is also the axis of the line sound source column. Therefore, the diagram shows a coaxial mid-high frequency horn 12 and a low-frequency horn 14, arranged back-to-back, with the low-frequency horn 14 facing the opening of the sound-focusing enclosure 24. The axis 16 of the mid-high frequency horn 12 and the axis 18 of the low-frequency horn 14 are parallel to each other; therefore, the cross-sectional view shows that axes 16 and 18 are collinear.

[0023] Figure 4 The diagram further illustrates the design of the second-order combined parabolic surface on the inner surface of the acoustic enclosure 24. In the cross-sectional view, the acoustic enclosure 24 is thin-shell shaped, and its cross-section resembles a second-order combined parabola. The mid-to-high frequency sound column, i.e., the acoustic center point F1 of the mid-to-high frequency horn 12, is at the focus of the first-order parabola P1. The opening width L1 of the first-order parabola P1 is equal to the wavelength corresponding to the mid-to-low frequency crossover frequency. The low-frequency sound column, i.e., the acoustic center F2 of the low-frequency horn 14, is at the focus of the second-order parabola P2. The opening width L2 of the second-order parabola P2 is equal to the wavelength corresponding to the lower limit of the controllable frequency of the low-frequency sound column. The first-order parabola P1 and the second-order parabola P2 intersect at point C. The second-order combined parabola is formed by the combination of the first-order parabola P1 before point C (i.e., to the left of point C in the figure) and the second-order parabola P2 after point C (i.e., to the right of point C in the figure). The second-order combined parabola extends along the axis of the sound source column to form a second-order combined parabolic surface. The second-order combined parabolic surface forms the inner surface of the sound-gathering cover.

[0024] Correspondingly, if no second-order parabola is set, the cross-section of the sound-concentrating enclosure will be a first-order parabola. The acoustic center point of the mid-to-high frequency sound column is the focus of the first-order parabola. The opening width of the first-order parabola is equal to the wavelength corresponding to the mid-to-low frequency crossover frequency. The first-order parabola extends along the axis of the line sound source sound column to form a first-order parabolic surface, which constitutes the inner surface of the sound-concentrating enclosure.

[0025] The design steps of the speaker unit of this utility model mainly include:

[0026] (1) Determine the structure and dimensions of the sound column. Based on the requirements of the amplification technical indicators under actual application conditions, select low, medium and high frequency horns, set the crossover frequency, and determine the dimensions of the sound column and the frequency response range of the controllable sound field according to the specifications of the horns.

[0027] (2) Calculate the crossover frequency. According to the line source theory, the acoustic center distance between two adjacent horns should be less than or equal to half the wavelength corresponding to the upper limit of the coupling frequency. Considering that the acoustic center distance between two adjacent horns is approximately equal to the diameter of the horn, the crossover frequency can be determined according to the specifications of the selected horn. For example, the crossover point for low and mid frequencies can be calculated based on the diameter of the low-frequency horn, and the crossover point for mid and high frequencies can be calculated based on the diameter of the mid-frequency horn.

[0028] (3) Determine the acoustic centers of the mid-to-high frequency horn and the low-frequency horn. Theoretically, the acoustic center of the horn is located at the center of the voice coil. The mid-to-high frequency horn uses a coaxial design, and through electronic delay compensation, its coupled acoustic center is located at the center of the mid-frequency and high-frequency horn centers. The acoustic center of the low-frequency horn is located at the center of the low-frequency horn voice coil.

[0029] (4) Determine the second-order combined parabolic surface of the acoustic shield. According to acoustic theory, the size of the baffle is approximately equal to the wavelength of the controllable frequency. Therefore, it can be deduced that the opening width L1 of the first-order parabola is equal to the wavelength corresponding to the crossover frequency of the low-frequency and mid-frequency ranges. In addition, the acoustic center F1 of the mid-high frequency horn is at the focus of the first-order parabola P1. Thus, the shape of the first-order parabola P1 corresponding to the mid-high frequency horn can be determined. Similarly, the opening width L2 of the second-order parabola P2 is equal to the wavelength corresponding to the lower limit of the controllable frequency of the low-frequency sound column. Furthermore, the acoustic center F2 of the low-frequency horn is at the focus of the second-order parabola P2. Thus, the shape of the second-order parabola P2 corresponding to the low-frequency horn can be determined. Subsequently, the first-order parabola P1 and the second-order parabola P2 intersect at point C. The second-order combined parabola is formed by the combination of the first-order parabola P1 before point C (i.e., to the left of point C in the figure) and the second-order parabola P2 after point C (i.e., to the right of point C in the figure). The second-order combined parabola extends along the axis of the sound source column to form a second-order combined parabolic surface, which constitutes the inner surface of the sound-gathering cover.

[0030] Correspondingly, if no second-order parabola is set, the cross-section of the sound-concentrating enclosure will be a first-order parabola. The acoustic center point of the mid-to-high frequency sound column is the focus of the first-order parabola. The opening width of the first-order parabola is equal to the wavelength corresponding to the mid-to-low frequency crossover frequency. The first-order parabola extends along the axis of the line sound source sound column to form a first-order parabolic surface, which constitutes the inner surface of the sound-concentrating enclosure.

[0031] (5) Combined Focusing. In actual assembly, actual focusing tests must be performed to ensure that the acoustic center F1 of the mid-to-high frequency horn is at the focus of the first-order parabola P1, and the acoustic center F2 of the low-frequency horn is at the focus of the second-order parabola P2. Accordingly, with the acoustic enclosure specifications fixed, the positions of the mid-to-high frequency horn and the low-frequency horn can be finely adjusted to meet the focusing requirements.

[0032] (6) Actual measurement confirmation. Once the actual measurement of the sound pressure difference inside and outside the sound-concentrating cover reaches the design target, the design scheme can be confirmed, mold opening can be carried out, and mass production can begin.

[0033] Figure 5 The figure shows the sound pressure test curves of the sound field inside and outside the sound-focusing enclosure according to an embodiment of the present invention. In the figure, curve A is the sound pressure test curve of the sound field inside the sound-focusing enclosure, and curve B is the sound pressure test curve of the sound field outside the sound-focusing enclosure. The test curves show that (1) the sound pressure inside the sound-focusing enclosure is generally greater than the sound pressure outside the sound-focusing enclosure, indicating that the sound-focusing enclosure has the function of reducing sound leakage. (2) In a specific frequency band, such as the 5K to 10K Hz band, the sound pressure inside the sound-focusing enclosure is about 30dB greater than the sound pressure outside the sound-focusing enclosure, indicating that the sound-focusing enclosure has a stronger ability to reduce sound leakage in this frequency band.

Claims

1. A sound amplification unit with controllable sound field range, characterized in that... It includes a sound-focusing enclosure and a line sound source column set inside the sound-focusing enclosure.

2. The sound amplification unit with controllable sound field range according to claim 1, characterized in that... The linear sound source columns include mid-to-high frequency sound columns and low frequency sound columns arranged back to back, with the low frequency sound columns facing the opening of the sound-gathering cover.

3. The sound amplification unit with controllable sound field range according to claim 2, characterized in that... The cross-section of the sound-gathering cover is a first-order parabola. The acoustic center point of the mid-to-high frequency sound column is the focus of the first-order parabola. The opening width of the first-order parabola is equal to the wavelength corresponding to the mid-to-low frequency crossover frequency. The first-order parabola extends along the axis of the line sound source sound column to form a first-order parabolic surface. The first-order parabolic surface forms the inner surface of the sound-gathering cover.

4. The sound amplification unit with controllable sound field range according to claim 2, characterized in that... The cross-section of the sound-gathering enclosure presents a second-order combined parabola. The acoustic center of the mid-to-high frequency sound column is at the focus of the first-order parabola. The opening width of the first-order parabola is equal to the wavelength corresponding to the mid-to-low frequency crossover frequency. The acoustic center of the low-frequency sound column is at the focus of the second-order parabola. The opening width of the second-order parabola is equal to the wavelength corresponding to the lower limit of the controllable frequency of the low-frequency sound column. The first-order parabola and the second-order parabola intersect at the intersection point. The second-order combined parabola is composed of the first-order parabola before the intersection point and the second-order parabola after the intersection point. The second-order combined parabola extends along the axis of the line sound source sound column to form a second-order combined parabolic surface. The second-order combined parabolic surface constitutes the inner surface of the sound-gathering enclosure.

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