Isolation structure for reducing acoustic crosstalk of parametric array loudspeaker to microphone

Abstract

The invention discloses an isolation structure for reducing acoustic crosstalk of a parametric array loudspeaker to a microphone, the isolation structure comprises a bottom plate and a plurality of sound isolation units located on the bottom plate, the plurality of sound isolation units are arranged around the microphone on the bottom plate, each sound isolation unit comprises a support body and a plurality of sound isolation parts, each sound isolation part is arranged at the edge of the support body, and each sound isolation part is arranged on the bottom plate. The plurality of sound barrier parts are circumferentially distributed at intervals along the edge of the supporting body, a notch is formed between every two adjacent sound barrier parts, and a sound barrier cavity communicated with the notch is formed between every two adjacent sound barrier parts and the supporting body; the isolation structure isolates the parametric array loudspeaker and the microphone, and the sounding surface of the parametric array loudspeaker is not opposite to the pickup surface of the microphone. According to the novel acoustic isolation structure for isolating the parametric array loudspeaker from the microphone, propagation of sound waves matched with the ultrasonic carrier frequency of the parametric array loudspeaker can be greatly inhibited, and the influence on target audible sound is extremely small.

Description

Technical Field

[0001] This invention relates to the field of acoustic crosstalk technology for microphones, and more specifically to an isolation structure for reducing acoustic crosstalk of a parametric array loudspeaker to a microphone. Background Technology

[0002] Unlike traditional loudspeakers, parametric array loudspeakers are loudspeakers capable of directional audio signal transmission. Specifically, they generate audible difference-frequency sound (frequency f1-f2) through nonlinear self-demodulation of air by finite-amplitude ultrasound (frequency f1 and f2). The main characteristic of parametric array loudspeakers is their strong directivity, enabling directional sound propagation through the air; therefore, parametric array loudspeakers are also known as ultra-directivity loudspeakers.

[0003] However, in existing electronic devices that integrate parametric array speakers and microphones, the high-intensity ultrasonic waves radiated by the parametric array speakers can severely interfere with the microphones, leading to signal saturation and distortion, and reducing the sound pickup quality.

[0004] Therefore, it is necessary to provide a new solution to address the ultrasonic crosstalk problem between the parametric array loudspeaker and the microphone. Summary of the Invention

[0005] The purpose of this invention is to provide an isolation structure that reduces acoustic crosstalk between a parametric array loudspeaker and a microphone.

[0006] To achieve the above objectives, this invention proposes an isolation structure to reduce acoustic crosstalk between a parametric array loudspeaker and a microphone. The isolation structure includes a base plate and multiple acoustic isolation units located on the base plate. The microphone is fixed to the base plate, and the multiple acoustic isolation units are arranged around the microphone on the base plate. Each acoustic isolation unit stands on the base plate and includes a support body and multiple acoustic blocking parts. Each acoustic blocking part is disposed along the edge of the support body, and the multiple acoustic blocking parts are circumferentially spaced along the edge of the support body. A gap is formed between adjacent acoustic blocking parts, and an acoustic blocking cavity communicating with the gap is formed between adjacent acoustic blocking parts and the support body. The isolation structure isolates the parametric array loudspeaker and the microphone, and the sound-emitting surface of the parametric array loudspeaker is not opposite the sound-collecting surface of the microphone. The height of each acoustic isolation unit is 0.5 to 3.0 times the wavelength of the sound wave corresponding to the ultrasonic frequency of the parametric array loudspeaker.

[0007] In a preferred embodiment, the microphone's pickup surface is embedded in the base plate, and / or the microphone is located at the center of the space enclosed by multiple acoustic isolation units; and / or the multiple acoustic isolation units are evenly spaced around the microphone in the circumferential direction; and / or the acoustic isolation units are made of a rigid material, including ABS, aluminum, or steel.

[0008] In a preferred embodiment, the interval between two adjacent acoustic isolation units is 0.5mm to 2.0mm.

[0009] In a preferred embodiment, the plurality of sound-blocking portions are evenly spaced along the circumferential edge of the support, and / or the width of the notch is 0.2mm to 1.0mm.

[0010] In a preferred embodiment, the support body includes a first support plate and a second support plate that is perpendicularly intersecting the first support plate, and a sound-blocking part is provided at each of the two outermost edges of the first support plate and the two outermost edges of the second support plate.

[0011] In a preferred embodiment, the first support plate and the second support plate are symmetrical about intersecting axes, and / or each sound-blocking part is symmetrical about the corresponding support plate.

[0012] In a preferred embodiment, the projection of each sound-blocking part on the base plate is arc-shaped with an arc length of 1.5mm to 2.5mm; and / or, the first support plate and the second support plate have the same length, specifically 2.0mm to 6.0mm.

[0013] In a preferred embodiment, the parametric array loudspeaker is located on the side of the isolation structure, and its sound-emitting surface is lower than the acoustic isolation unit.

[0014] In a preferred embodiment, the parametric array loudspeaker is arranged side by side with the base plate, and its sound-emitting surface is flush with the top surface of the base plate.

[0015] In a preferred embodiment, the parametric array loudspeaker employs an electrostatic ultrasonic transducer array, and / or the parametric array loudspeaker includes a substrate layer and a vibrating layer, with an air gap formed between the substrate layer and the vibrating layer, and the vibrating layer vibrates to emit ultrasonic waves under the drive of a driving signal applied between the substrate layer and the vibrating layer.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention proposes a novel acoustic isolation structure for isolating parametric array loudspeakers and microphones. Based on the principle of phonon crystals, the structure forms an acoustic bandgap in a frequency band that matches the ultrasonic carrier frequency of the parametric array loudspeaker through periodically arranged scattering units, thereby greatly suppressing the propagation of sound waves at that frequency. In other words, it can efficiently attenuate specific ultrasonic frequencies (i.e., frequencies that match the ultrasonic carrier frequency of the parametric array loudspeaker) with minimal impact on the audible sound of the target.

[0017] 2. This invention effectively weakens acoustic wave diffraction and achieves comprehensive isolation of crosstalk signals by optimizing several parameters of the isolation structure (including the height of the acoustic isolation unit, the spacing between adjacent acoustic isolation units, the width of the gap, etc.); and the bandgap frequency can be flexibly adjusted through these geometric parameters of the acoustic isolation unit to adapt to different product requirements.

[0018] 3. This invention adopts the principle of local resonance, is small in size, and is easy to integrate into devices with limited space; moreover, this invention can effectively isolate direct waves and diffracted waves at the same time, solving the problem of severe diffraction of traditional baffles. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the acoustic isolation structure (including a parametric array loudspeaker and a microphone) of the present invention; Figure 2 for Figure 1 A top-view structural diagram; Figure 3 This is a top view schematic diagram of the acoustic isolation structure of the present invention; Figure 4 This is a three-dimensional structural diagram of the acoustic isolation unit of the present invention; Figure 5 This is a top view of the acoustic isolation unit of the present invention. Figure 6 This is a schematic diagram of the parametric array loudspeaker in one embodiment of the present invention; Figure 7 This is a simulation diagram of broadband transmission loss of an acoustic isolation structure in a specific embodiment of the present invention.

[0020] The attached figures are labeled as follows: 1. Isolation structure; 11. Base plate; 12. Acoustic isolation unit; 121. Support body; 1211. First support plate; 1212. Second support plate; 122. Acoustic blocking part; 13. Notch; 2. Parametric array loudspeaker; 21. Substrate layer; 22. Vibrating layer; 23. Air gap; 3. Microphone. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0022] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising" shall be understood to include the stated elements or components without excluding other elements or other components.

[0023] Combination Figure 1 and Figure 2As shown, the present invention discloses an isolation structure 1 for reducing acoustic crosstalk between a parametric array loudspeaker and a microphone, used to isolate the parametric array loudspeaker 2 and the microphone 3. It includes a base plate 11 and a plurality of acoustic isolation units 12 located on the base plate 11. The plurality of acoustic isolation units 12 surround the microphone 3 to shield the ultrasonic waves emitted by the parametric array loudspeaker 2 from the microphone 3.

[0024] In this embodiment, the microphone 3 is perpendicular to the base plate 11, and its pickup surface is embedded and fixed within the base plate 11. Multiple acoustic isolation units 12 on the base plate 11 are arranged around the pickup surface of the microphone 3, preferably with the pickup surface of the microphone 3 located at the center of the space enclosed by the multiple acoustic isolation units 12. In practice, the multiple acoustic isolation units 12 can be arranged in a square, circular, or other geometric pattern, and can be arranged with uniform or uneven spacing. This invention does not impose any limitations on this, as long as the microphone 3 is completely surrounded. In this embodiment, the multiple acoustic isolation units 12 are arranged around the microphone 3 with uniform circumferential spacing in a square pattern.

[0025] Preferably, combined with Figure 3 As shown, the spacing d1 between adjacent acoustic isolation units 12 ranges from 0.5mm to 2.0mm. The beneficial technical effects of this range are: 1. Suppressing gap acoustic leakage: This spacing is much smaller than the wavelength of the ultrasonic carrier wave (e.g., 40kHz) of the parametric array loudspeaker, less than 4 / 1000. According to acoustic waveguide theory, sound waves are difficult to propagate through diffraction in this subwavelength-scale slit, effectively preventing high-intensity direct ultrasonic waves from leaking into the microphone area through the gap between units. 2. Maximizing acoustic bandgap attenuation: Within the limited space of the base plate, a smaller spacing means that more acoustic isolation units 12 can be arranged with a higher fill rate. The increased density of the acoustic isolation units 12 significantly enhances the overall acoustic bandgap depth, maximizing the transmission loss to the target frequency, thus achieving more thorough acoustic isolation.

[0026] Each acoustic isolation unit 12 is mounted vertically on the base plate 11. To balance device integration and acoustic isolation, its height is preferably 0.5 to 3.0 times the wavelength of the sound wave corresponding to the ultrasonic frequency of the parametric array speaker 2. Specifically, in compact devices, it is preferably 0.5λ to 1.5λ (λ being the sound wave wavelength). For example, for a carrier frequency of 40kHz (wavelength approximately 8.6mm), the height of the acoustic isolation unit 12 is preferably set to 4.5mm to 13mm. At this subwavelength or near-wavelength scale, although the simple geometric acoustic shadowing effect is weak, the present invention utilizes the acoustic band-stop effect excited by the local resonant unit to play a dominant role, effectively suppressing sound wave creep and diffraction along the surface at low heights, solving the problem of sound insulation failure of traditional low baffles. In high-performance isolation scenarios, it is preferably 1.5λ to 3.0λ: for example, set to 13mm to 26mm. At this scale, the geometric acoustic shadowing effect and the resonant band-stop effect produce a synergistic effect. The higher height first attenuates most of the direct wave energy through physical reflection, while the resonant structure at the edge further captures and consumes the remaining diffracted leakage energy, thereby achieving a deep acoustic isolation effect close to -30dB or even lower. Furthermore, in implementation, the material of each acoustic isolation unit 12 is preferably a rigid material, such as ABS, aluminum, or steel.

[0027] Combination Figure 4 and Figure 5 As shown, each acoustic isolation unit 12 specifically includes a support body 121 and multiple acoustic blocking parts 122. The support body 121 specifically includes intersecting first support plates 1211 and second support plates 1212. In this embodiment, the first support plates 1211 and second support plates 1212 are perpendicularly intersecting, forming a cross-shaped distribution, and the first support plates 1211 and second support plates 1212 are preferably symmetrical about the intersecting axis. Of course, the present invention does not limit the number of support plates included in the support body 121, such as three intersecting support plates. In practice, the first support plates 1211 and second support plates 1212 have the same length, preferably 2.0 mm to 6.0 mm.

[0028] Each sound-blocking part 122 is disposed on the edge of the support body 121, and multiple sound-blocking parts 122 are distributed circumferentially at intervals along the edge of the support body 121, preferably distributed circumferentially at intervals along the edge of the support body 121. In this embodiment, a sound-blocking part 122 is provided at the two outermost edges (i.e., the two side ends) of the first support plate 1211 and the two outermost edges (i.e., the two side ends) of the second support plate 1212, that is, each sound isolation unit 12 has four sound-blocking parts 122. These four sound-blocking parts 122 are evenly distributed circumferentially around the middle support body 121, and preferably each sound-blocking part 122 is symmetrical about the corresponding support plate axis. In this embodiment, the projection of each sound-blocking part 122 on the base plate 11 is arc-shaped, and its arc length is 1.5mm to 2.5mm. The combination of parameters—the lengths of the first and second support plates and the arc length of the acoustic barrier portion—ensures that the acoustic isolation unit has a compact structure and that the acoustic barrier cavity has suitable acoustic capacity, which, in conjunction with the acoustic sensing of the notch, forms a strong blocking band against the ultrasonic carrier wave. Of course, the present invention does not limit the shape of the acoustic barrier portion 122.

[0029] A notch 13 is formed between two adjacent sound-blocking parts 122 to allow sound waves to enter. That is, in this embodiment, each sound-blocking unit has four notches 13, and these four notches 13 are evenly spaced around the center of the central support 121. In implementation, combined with... Figure 3 As shown, the width d2 of each notch 13 is preferably 0.2mm to 1.0mm. This specific width range can bring the following key technical effects: 1. Precise frequency tuning: The notch width d2 directly determines the acoustic quality of the resonator. Within the narrow slit range of 0.2mm to 1.0mm, a sufficiently large acoustic quality can be provided, thereby effectively reducing the inherent resonant frequency of the acoustic isolation unit 12 to the ultrasonic carrier frequency band of the parametric array loudspeaker (e.g., 40kHz). If the width is too large, the resonant frequency will drift to a higher frequency band, resulting in the failure of carrier isolation. 2. Enhanced thermal viscosity dissipation: This sub-millimeter narrow slit design makes full use of the thermal viscosity effect of air in the microchannel. When high-intensity ultrasonic waves attempt to pass through the notch into the acoustic barrier cavity, air molecules generate intense friction and heat exchange at the slit boundary layer, efficiently converting acoustic energy into heat energy for dissipation, thereby significantly improving the peak attenuation of resonant sound absorption. A sound-blocking cavity 122 communicating with the notch 13 is formed between the adjacent sound-blocking part 122 and the first support plate 1211 and the second support plate 1212 of the support body 121.

[0030] The parametric array speaker 2 can be positioned in any location except that its sound-emitting surface is not opposite to the pickup surface of the microphone 3. Preferably, it is positioned on the side of the isolation structure 1, and its sound-emitting surface is lower than the sound isolation unit 12. In this embodiment, the parametric array speaker 2 is arranged side by side with the base plate 11, and its sound-emitting surface is flush with the top surface of the base plate 11.

[0031] In implementation, the parametric array loudspeaker 2 can be an electrostatic ultrasonic transducer array. In this embodiment, the parametric array loudspeaker 1 includes a substrate layer 21 and a vibrating layer 22. The frames of the substrate layer 21 and the vibrating layer 22 are attached to each other, and an air gap 23 is formed between them to allow the vibrating layer 22 to vibrate and emit ultrasonic waves. In implementation, the air gap 23 can be formed in various ways, such as by setting insulating protrusions (not shown) between the substrate layer 21 and the vibrating layer 22, and forming the air gap 23 under the support of the insulating protrusions. Of course, it can also be formed by grooves or other forms on the substrate layer 21 or the vibrating layer 22. The present invention does not limit this. Both the substrate layer 21 and the vibrating layer 22 have conductive layers (not shown) to form a lower electrode and an upper electrode for inputting a drive signal. The vibrating layer 22 emits an audio signal modulated by an ultrasonic carrier under the drive signal loaded between the substrate layer 21 and the vibrating layer 22. In practice, the parametric array loudspeaker can be completely transparent. Specifically, for example, the substrate layer 21 can be made by coating an ITO (indium tin oxide) conductive layer on transparent glass, and the vibrating layer 22 can be made by coating an ITO conductive layer on a transparent PET (polyethylene terephthalate) layer. This invention does not limit this.

[0032] The advantages of this invention are as follows: 1. This invention proposes a novel acoustic isolation structure for isolating parametric array loudspeakers and microphones. Based on the principle of phonon crystals, this structure forms an acoustic bandgap in a frequency band matching the ultrasonic carrier frequency of the parametric array loudspeaker through periodically arranged scattering units. This greatly suppresses the propagation of sound waves at that frequency, effectively attenuating specific ultrasonic frequencies (i.e., frequencies matching the ultrasonic carrier frequency of the parametric array loudspeaker) with minimal impact on the target audible sound. 2. This invention effectively weakens sound wave diffraction by optimizing several parameters of the isolation structure (including the height of the acoustic isolation unit, the spacing between adjacent acoustic isolation units, and the width of the gap, etc.), achieving comprehensive isolation of crosstalk signals. Furthermore, the bandgap frequency can be flexibly adjusted through these geometric parameters of the acoustic isolation unit to adapt to different product requirements. 3. This invention adopts the principle of local resonance (i.e., using an acoustic resonance system composed of "notch + cavity" to accurately capture or even reflect specific ultrasonic frequency bands), has a small size, and is easy to integrate into devices with limited space; moreover, this invention can effectively isolate direct waves and diffracted waves at the same time (i.e., using macroscopic geometric shielding to cut off the direct path of sound waves and coupling microscopic resonance units to suppress diffraction leakage at the edges), solving the problem of severe diffraction of traditional baffles.

[0033] To further verify the beneficial effects of the present invention, this embodiment constructs an acoustic isolation structure model for a parametric array loudspeaker with a specific carrier frequency of 40kHz, and performs acoustic simulation analysis using the finite element method (FEM).

[0034] 1. Model Parameter Settings: In this specific embodiment, the geometric parameters of the acoustic isolation unit are set as follows to ensure the formation of an effective acoustic bandgap around 40kHz: The lattice constant (i.e., the unit spacing, the distance between the center points of two acoustic isolation units) is set to 6.0 mm. This size is smaller than the 40 kHz acoustic wavelength (approximately 8.6 mm), which conforms to the subwavelength design principle of phononic crystals and ensures a compact structure.

[0035] The lengths of the first and second support plates are set to 5.0 mm (i.e., the lateral span of the acoustic isolation unit).

[0036] Arc length of the acoustic barrier: set to 2.0mm.

[0037] Notch width (d2): set to 0.5mm. This narrow slit size, when matched with the acoustic barrier cavity, can produce the required acoustic quality and thermal viscous loss.

[0038] Sound isolation unit height: set to 10.0 mm (approximately 1.2 times the wavelength of sound waves).

[0039] Material: ABS engineering plastic.

[0040] Transmission loss analysis: The simulation frequency range was set from 1kHz to 60kHz to comprehensively evaluate the impact of the structure on different frequency bands.

[0041] Depend on Figure 7 As shown, the present invention: In the audible frequency range (1kHz-20kHz): transmission loss remains at an extremely low level (< 5dB), and the curve is flat, verifying that the structure has almost no attenuation of human voice and ambient sound picked up by the microphone, and has good "acoustic transparency".

[0042] In the ultrasonic carrier band: the transmission loss curve rises sharply at 40kHz, showing a significant attenuation peak with a transmission loss of 25.9dB at this peak. Furthermore, the bandwidth above the 15dB effective isolation threshold reaches approximately 7.5kHz (covering the 36.5kHz to 43.9kHz frequency band), effectively resolving the crosstalk risks associated with parametric arrays.

[0043] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An isolation structure to reduce parametric array loudspeaker to microphone acoustic crosstalk, characterized by, The isolation structure comprises a bottom plate and a plurality of sound isolation units arranged on the bottom plate, the microphone is fixed on the bottom plate, the plurality of sound isolation units are arranged around the microphone on the bottom plate, each sound isolation unit stands on the bottom plate, and each sound isolation unit comprises a support body and a plurality of sound resistance parts, each sound resistance part is arranged at the edge of the support body, and a plurality of sound resistance parts are distributed along the edge of the support body in a circumferential direction, a gap is formed between adjacent sound resistance parts, and a sound resistance cavity is formed between adjacent sound resistance parts and the support body, which communicates with the gap; the isolation structure isolates the parametric array loudspeaker and the microphone, and the sound emitting surface of the parametric array loudspeaker is not opposite to the sound pickup surface of the microphone, the height of each sound isolation unit is 0.5-3.0 times the wavelength of the ultrasonic frequency corresponding to the parametric array loudspeaker.

2. A baffle for reducing acoustic cross-talk between a parametric array loudspeaker and a microphone as defined in claim 1, wherein, The sound pickup surface of the microphone is embedded in the bottom plate, and / or the microphone is located at the center of the space surrounded by the plurality of sound isolation units; and / or the plurality of sound isolation units are uniformly and circumferentially distributed around the microphone. And / or, the material of the sound isolation unit is a hard material, which includes ABS material, aluminum or steel.

3. A baffle for reducing acoustic cross-talk between a parametric array loudspeaker and a microphone according to claim 1, wherein, The interval between the two adjacent sound isolation units is 0.5-2.0 mm.

4. A baffle for reducing acoustic cross-talk between a parametric array loudspeaker and a microphone according to claim 1, wherein, A plurality of sound resistance parts are uniformly and circumferentially distributed along the edge of the support body, and / or the width of the gap is 0.2-1.0 mm.

5. A barrier structure for reducing acoustic cross-talk from a parametric array loudspeaker to a microphone according to claim 1 or 4, wherein, The support body comprises a first support plate and a second support plate arranged perpendicularly intersecting the first support plate, and each of the two outermost edges of the first support plate and the two outermost edges of the second support plate is provided with a sound resistance part.

6. A barrier structure to reduce acoustic cross-talk from a parametric array loudspeaker to a microphone according to claim 5, wherein, The first support plate and the second support plate are axisymmetric about the intersecting axis, and / or each sound resistance part is axisymmetric about the corresponding support plate.

7. A baffle for reducing acoustic cross-talk between a parametric array loudspeaker and a microphone according to claim 6, wherein, The projection of each sound resistance part on the bottom plate is in the shape of a circular arc, and the arc length is 1.5-2.5 mm; and / or the length of the first support plate and the second support plate is the same, specifically 2.0-6.0 mm.

8. A baffle for reducing acoustic cross-talk between a parametric array loudspeaker and a microphone according to claim 1, wherein, The parametric array loudspeaker is located at the side edge of the isolation structure, and its sound emitting surface is lower than the sound isolation unit.

9. A barrier structure to reduce acoustic cross-talk of a parametric array loudspeaker to a microphone according to claim 8, wherein, The parametric array loudspeaker is arranged side by side with the bottom plate, and its sound emitting surface is flush with the top surface of the bottom plate.

10. A baffle structure for reducing acoustic cross-talk between a parametric array loudspeaker and a microphone according to claim 1, 8 or 9, wherein, The parametric array loudspeaker adopts an electrostatic ultrasonic transducer array, and / or the parametric array loudspeaker comprises a substrate layer and a vibration layer, an air gap is formed between the substrate layer and the vibration layer, and the vibration layer vibrates to emit ultrasonic waves under the driving of the driving signal loaded between the substrate layer and the vibration layer.

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