An in-ear earphone acoustic cavity optimization design method based on a bionic cochlea structure

Abstract

The application relates to the field of information technology, in particular to an in-ear earphone acoustic cavity optimization design method based on a bionic cochlea structure, which comprises the following steps: carrying out finite element analysis on the acoustic cavity geometric model, calculating the propagation path and pressure distribution of sound waves in the cavity, and judging whether the sound waves form standing waves in a predetermined frequency range; if the finite element analysis result shows that standing waves exist, adjusting the spiral angle parameter of the logarithmic spiral model, recalculating the sound wave propagation characteristics in the model, and stopping until the standing wave phenomenon is suppressed; according to the optimized spiral taper structure model, combining the acoustic characteristics of the earphone driving unit, calculating the incidence angle of sound waves at the entrance, and judging whether the sound waves can enter the acoustic cavity efficiently; if the sound wave incidence angle exceeds the preset range, adjusting the entrance diameter parameter of the logarithmic spiral model, recalculating the sound wave incidence angle, and stopping until the matching requirement of the driving unit is met.

Description

Technical Field

[0001] The present invention relates to the field of information technology, specifically to the field of in-ear headphones, and more particularly to a method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure. Background Art

[0002] In the design of the in-ear headphone cavity based on the bionic cochlear structure, the key technical problem that needs to be solved in the spiral tapered structure of the sound cavity is how to accurately set the range of the inlet diameter of 6mm and the outlet diameter of 3.2mm to ensure that the sound waves can achieve a smooth transition during propagation while avoiding the occurrence of mid- and high-frequency resonance. The cylindrical sound cavity design of traditional in-ear headphones is prone to forming standing waves at specific frequencies due to its simple structure, resulting in serious distortion of the sound quality (total harmonic distortion THD>5%). In addition, the simple cylindrical structure is prone to local pressure concentration when worn, affecting the user experience.

[0003] In order to solve this problem, a bionic design approach was adopted, and the acoustic cavity was designed as a spiral tapered structure with an entrance diameter of 6mm, which tapers to 3.2mm according to a logarithmic spiral, and the spiral angle is set to 15°. This design can not only effectively suppress the formation of standing waves, but also make the sound waves more uniform and smooth when propagating in the cavity. However, the realization of this spiral structure requires precise control of the parameters of the tapering range. The setting of the entrance diameter needs to take into account the matching with the headphone driver unit to ensure that the sound waves can efficiently enter the acoustic cavity; the exit diameter needs to be adapted to the size of the wearer's ear canal, ensuring the output effect of the sound waves while avoiding excessive pressure on the ear canal.

[0004] In addition, the inner wall of the cavity is equipped with micron-scale scale protrusions with a height of 0.1mm and a spacing of 0.3mm. They are manufactured using a 3D printing titanium alloy integrated molding process. This design aims to further optimize the diffusion of sound waves in the cavity and reduce sound wave reflection and distortion, but it also places higher requirements on the manufacturing process, especially in terms of precision control and material selection. Through the implementation of the above technical solutions, the overall performance of the acoustic cavity has been significantly improved, but various parameters still need to be fine-tuned during the design and manufacturing process to ensure that the acoustic performance and wearing comfort of the final product are optimally balanced. Summary of the Invention

[0005] The present invention provides a method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure, the method comprising the following steps:

[0006] S101, obtaining a logarithmic spiral mathematical model, and constructing a three-dimensional geometric model of a spiral tapered acoustic cavity structure based on parameters of an inlet diameter of 6 mm, an outlet diameter of 3.2 mm, and a spiral angle of 15°;

[0007] S102, performing finite element analysis on the acoustic cavity geometric model, calculating the propagation path and pressure distribution of the sound wave in the cavity, and determining whether the sound wave forms a standing wave within a predetermined frequency range;

[0008] S103. If the finite element analysis results show the existence of standing waves, adjust the spiral angle parameters of the logarithmic spiral model and recalculate the sound wave propagation characteristics in the model until the standing wave phenomenon is suppressed;

[0009] S104. Calculate the incident angle of the sound wave at the entrance based on the optimized spiral tapered structure model and the acoustic characteristics of the headphone driver unit to determine whether the sound wave can efficiently enter the acoustic cavity.

[0010] S105: If the sound wave incident angle exceeds the preset range, adjust the inlet diameter parameter of the logarithmic spiral model and recalculate the sound wave incident angle until the matching requirement of the drive unit is met;

[0011] S106. Add inner wall scale protrusion features to the acoustic cavity geometry model, with a protrusion height of 0.1 mm and a spacing of 0.3 mm, and simulate the diffusion effect of sound waves in the cavity based on computational fluid dynamics;

[0012] S107. If the simulation results show that the sound wave diffusion is uneven, adjust the geometric parameters of the scale protrusions and re-perform the fluid dynamics calculation until the sound wave diffuses evenly in the cavity and there is no significant reflection within the predetermined frequency range;

[0013] S108. Import the final optimized acoustic cavity model into the 3D printing system, use titanium alloy material, and manufacture the acoustic cavity entity through precision molding technology to complete the design of the in-ear headphone cavity based on the bionic cochlear structure.

[0014] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0015] The present invention discloses a method for optimizing the acoustic cavity design of in-ear headphones based on a bionic cochlear structure. The method first constructs a spiral tapered structure of the acoustic cavity of a logarithmic spiral model, calculates the sound wave propagation characteristics through finite element analysis, and suppresses the standing wave phenomenon by adjusting the spiral angle parameters. Then, combined with the characteristics of the drive unit, the entrance diameter is optimized to ensure the efficient entry of sound waves. In order to further improve the diffusion of sound waves, micron-scale scale protrusions are added to the inner wall of the cavity, and its geometric parameters are optimized through computational fluid dynamics simulation. Finally, titanium alloy materials and precision molding processes are used to manufacture the optimized acoustic cavity entity. The present invention effectively suppresses standing waves and achieves uniform diffusion of sound waves through bionic design and multi-step iterative optimization, thereby improving the acoustic performance and listening experience of in-ear headphones. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1This is a flow chart of a method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure according to the present invention.

[0017] Figure 2 Schematic diagram of an in-ear headphone acoustic cavity optimization design method based on a bionic cochlear structure according to the present invention.

[0018] Figure 3 This is another schematic diagram of the in-ear headphone acoustic cavity optimization design method based on the bionic cochlear structure of the present invention. DETAILED DESCRIPTION

[0019] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] like Figure 1-3 In this embodiment, a method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure may specifically include:

[0021] S101. Obtain a mathematical model of a logarithmic spiral, and construct a three-dimensional geometric model of a spiral tapered structure of a sound cavity based on parameters of an inlet diameter of 6 mm, an outlet diameter of 3.2 mm, and a spiral angle of 15°.

[0022] Obtain the inlet diameter and outlet diameter of the acoustic cavity, determine the proportional relationship between the two, and obtain the tapering ratio of the spiral structure; based on the proportional relationship, use the logarithmic spiral equation to construct a three-dimensional spatial mathematical model of the spiral, and the mathematical model uses the inlet diameter, outlet diameter and spiral angle as input parameters; based on the mathematical model, generate three-dimensional point cloud data of the spiral and construct the spatial structure of the spiral; obtain the thickness parameters of the acoustic cavity wall, apply the thickness parameters to the spiral spatial structure, and generate a three-dimensional geometric model of the acoustic cavity spiral tapering structure; use the finite element analysis method to grid the three-dimensional geometric model and calculate the flow field distribution inside the acoustic cavity; if the flow field distribution meets the preset conditions, output the three-dimensional geometric model; if the flow field distribution does not meet the preset conditions, adjust the spiral angle and reconstruct the mathematical model until a three-dimensional geometric model that meets the preset conditions is obtained.

[0023] Specifically, acoustic cavity structure design begins with measuring the inlet and outlet diameters. A typical inlet diameter might be 20 cm and an outlet diameter of 5 cm, resulting in a taper ratio of 4:1. This ratio directly influences the propagation characteristics of sound waves and the change in sound pressure level. The cavity's taper ratio determines the degree of sound energy concentration; a larger taper ratio achieves a stronger sound energy focusing effect. A logarithmic spiral is a special curve characterized by a constant angle between any ray originating from the pole and the tangent of the curve. In acoustic cavity design, the spiral angle is typically selected between 30 and 60 degrees. This range ensures efficient sound wave propagation while avoiding the manufacturing difficulties associated with overly steep structures. The coordinates of a two-dimensional spiral can be expressed using a polar coordinate equation and then converted to a rectangular coordinate system. For example, for a logarithmic spiral with a starting radius of 10 cm and a spiral angle of 45 degrees, its coordinate points will gradually converge towards the center as the spiral angle changes. When converting to three-dimensional space, the spiral's rise angle must be considered; a rise angle of 15 to 25 degrees generally yields an ideal spatial structure. The thickness of the acoustic cavity wall must be designed based on material strength and processing technology. For metal materials, the wall thickness is typically between 3 mm and 8 mm to ensure structural strength and effectively block external noise interference. Although thicker walls increase weight, they provide better sound insulation and structural stability. In finite element analysis, mesh density directly impacts calculation accuracy. Areas with large changes in curvature, such as spiral corners, require a finer mesh. Generally speaking, the minimum mesh size should not be larger than one-tenth of the sound wave wavelength. For a 20 kHz sound wave, the mesh size should be less than 0.17 mm. Evaluation criteria for sound field distribution include sound pressure level uniformity and sound energy focusing. At the outlet, the sound pressure level is typically required to be at least 15 decibels higher than at the inlet. If uneven sound pressure distribution or unsatisfactory sound energy focusing is observed, the helix angle can be adjusted to optimize the effect. For example, adjusting the helix angle from 45 degrees to 50 degrees may improve sound energy focusing. If the peak sound pressure exceeds the design requirement of 150 decibels or the distribution is uneven, the helix angle parameters need to be redesigned.

[0024] S102: Perform finite element analysis on the acoustic cavity geometry model, calculate the propagation path and pressure distribution of the sound wave in the cavity, and determine whether the sound wave forms a standing wave within a predetermined frequency range.

[0025] Acquire an acoustic cavity model containing geometric parameters, wherein the acoustic cavity model includes boundary conditions and material properties; adopt a finite element analysis method to divide the acoustic cavity model into grid units to generate a calculation domain; establish a sound pressure calculation equation at the node of each grid unit according to the sound wave propagation equation; obtain a sound pressure distribution diagram in the acoustic cavity by solving the sound pressure calculation equation group; extract node values ​​from the sound pressure distribution diagram, and calculate the sound pressure amplitude at each frequency; if the sound pressure amplitude at a certain frequency presents a periodic distribution within a preset frequency range, it is determined that a standing wave is formed at this frequency; compare the frequency range in which the standing wave is formed with the preset frequency range to obtain an analysis result of the standing wave formation situation.

[0026] Specifically, the geometric parameters of the acoustic cavity model include key dimensions such as length, diameter, and wall thickness. These parameters directly influence the propagation characteristics of sound waves within the cavity. For example, a cylindrical acoustic cavity has a length of 500 mm, an inner diameter of 100 mm, and a wall thickness of 10 mm. Regarding boundary conditions, an acoustic pressure excitation with an amplitude of 1 Pa and a frequency range of 100-1000 Hz can be applied to the cavity inlet, while the outlet is set as a free boundary. The cavity material used is steel, with a density of 7850 kg / m³ and a Young's modulus of 210 GPa. When creating finite element meshes, the relationship between the wavelength of the sound wave and the mesh size must be considered. Typically, at least 6-8 mesh elements are required per wavelength to ensure computational accuracy. For the above acoustic cavity model, at an analysis frequency of 500 Hz, the wavelength of the sound wave is approximately 0.7 meters, so the mesh size should be no larger than 0.1 meters. A hexahedral mesh is used, with appropriate densification at the cavity walls, resulting in approximately 20,000 mesh elements. When establishing the sound pressure calculation equation at each grid node, the propagation characteristics of sound waves in the fluid medium must be considered. The sound pressure equation includes a pressure gradient term, a time derivative term, and a sound source term. For harmonic excitation, frequency domain analysis can be used to convert the time domain equation into a frequency domain equation for solution. By solving the sound pressure equations, the sound pressure distribution at different locations within the acoustic cavity can be obtained. Taking 500 Hz excitation as an example, the sound pressure exhibits a clear periodic distribution along the axial direction, with a peak of approximately 1.8 Pa and a trough of approximately 0.2 Pa occurring in the center of the cavity, indicating the formation of a stable standing wave field at this frequency. The periodic distribution of sound pressure amplitude is an important indicator for determining the formation of standing waves. When the distance between adjacent peaks on the sound pressure distribution curve equals half a wavelength, a standing wave is considered to have formed. Analysis shows that clear standing waves are observed in the acoustic cavity within the frequency range of 400-600 Hz, and the waveforms are relatively stable. This is consistent with the expected operating frequency range of 350-650 Hz, indicating that the acoustic cavity design meets the requirements for standing wave formation. There's a corresponding relationship between the geometric dimensions of the acoustic cavity and the frequency of standing waves. Standing waves are most likely to form when the cavity length is an integer multiple of the acoustic wavelength. Taking the aforementioned acoustic cavity as an example, its fundamental frequency is approximately 340 Hz, with resonant frequencies of 680 Hz, 1020 Hz, and so on. By properly selecting the cavity dimensions, the standing wave frequency can be adjusted to fall within the desired range. This periodic distribution of sound pressure helps to enhance the local concentration of acoustic energy and can be used in applications such as acoustic processing and acoustic energy harvesting.

[0027] S103. If the finite element analysis results show the existence of standing waves, adjust the spiral angle parameters of the logarithmic spiral model and recalculate the sound wave propagation characteristics in the model until the standing wave phenomenon is suppressed.

[0028] Obtain finite element analysis results, and determine whether standing waves exist in the finite element analysis results; if standing waves exist, extract the spiral angle parameters of the logarithmic spiral model, and use the spiral angle parameters as adjustment targets; according to a preset spiral angle threshold range, use a gradient descent algorithm to adjust the spiral angle parameters to obtain adjusted spiral angle parameters; substitute the adjusted spiral angle parameters into a sound wave propagation characteristic calculation model, recalculate the sound wave propagation characteristics, and obtain an updated sound field distribution; use a support vector machine algorithm to analyze the updated sound field distribution to determine whether the standing wave phenomenon is suppressed; if the standing wave phenomenon is not completely suppressed, repeatedly adjust the spiral angle parameters and recalculate the sound wave propagation characteristics until the standing wave phenomenon is completely suppressed.

[0029] Specifically, the presence of standing waves is typically manifested as a spatially periodic distribution of sound pressure amplitude. Sound pressure peaks may occur at specific locations within the cavity, such as at the boundaries or at the center. For example, in a rectangular cavity, when the incident wave frequency is the first-order longitudinal mode frequency, sound pressure peaks occur at the two end walls, with a sound pressure node at the center. The presence of standing waves can be determined by analyzing the sound pressure distribution diagrams from finite element calculation results. The spiral angle of a logarithmic spiral is a key parameter describing the shape of the curve. A larger spiral angle causes the curve to unfold more rapidly, increasing the curvature of the sound wave propagation path. A smaller spiral angle tightens the curve, extending the sound wave propagation path. For example, in a certain acoustic cavity, an initial spiral angle of 45 degrees exhibited significant standing waves at a frequency of 2 kilohertz. Using a gradient descent algorithm, the spiral angle can be gradually adjusted. The algorithm calculates the direction and step size for adjusting the spiral angle based on the difference between the sound pressure amplitude and a preset threshold. Calculation of sound wave propagation characteristics requires consideration of medium properties and boundary conditions. For example, the speed of sound in air is approximately 340 meters per second, and the density is approximately 1.2 kilograms per cubic meter. Boundary conditions include total reflection at rigid boundaries and partial absorption at flexible boundaries. Substituting the adjusted helix angle into the computational model yields a new sound field distribution. The support vector machine algorithm establishes a classification hyperplane to determine whether the sound field distribution conforms to standing wave characteristics. Characteristic parameters such as sound pressure amplitude and phase distribution can be used as the classification basis. The classification results can be used to evaluate the effectiveness of standing wave suppression. For example, in one case, standing waves were present in the original sound field between 1,500 Hz and 2,000 Hz. After three adjustments to the helix angle parameter, gradually adjusting the angle from 45 degrees to 30 degrees, the standing waves were significantly suppressed, with the peak sound pressure reduced by 60%. If the first round of adjustments fails to fully suppress the standing waves, iterative optimization is required. Each round of iteration fine-tunes the helix angle parameters based on the results of the previous round. In practical applications, it may be necessary to balance computational efficiency with suppression effectiveness and set appropriate termination criteria for the iterations. For example, suppression is considered achieved when the change in peak sound pressure after two consecutive rounds of adjustments is less than 5%, or when the standing wave sound pressure amplitude is reduced below a threshold.

[0030] S104. Based on the optimized spiral tapered structure model and the acoustic characteristics of the headphone driver unit, the incident angle of the sound wave at the entrance is calculated to determine whether the sound wave can efficiently enter the acoustic cavity.

[0031] The geometric parameters of the optimized spiral tapered structure model are obtained, and combined with the acoustic characteristic parameters of the headphone drive unit, the propagation direction of the sound wave at the entrance is obtained; the incident angle of the sound wave at the entrance is calculated according to the angle between the sound wave propagation direction and the normal at the entrance; if the incident angle is less than a preset threshold, it is determined that the sound wave can efficiently enter the sound cavity; an acoustic simulation algorithm is used to simulate the propagation path of the sound wave in the sound cavity; according to the propagation path of the sound wave in the sound cavity, the attenuation of the sound wave in the sound cavity is analyzed; according to the sound wave attenuation, the geometric parameters of the spiral tapered structure model are adjusted to obtain an optimized spiral tapered structure model, and the optimized spiral tapered structure model is used to optimize the acoustic performance of the sound cavity; the acoustic performance parameters of the optimized sound cavity are obtained, and the incident angle of the sound wave at the entrance is recalculated according to the acoustic performance parameters; if the recalculated incident angle meets the preset conditions, it is determined that the optimization of the spiral tapered structure model is completed.

[0032] Specifically, the geometric parameters of the spiral tapered structure model primarily include the spiral length, spiral angle, and tapering ratio. For example, consider an in-ear headphone with a dynamic acoustic driver unit, an 8mm diaphragm diameter, and an operating frequency range of 20 Hz to 20,000 Hz. When optimizing the acoustic cavity structure, the propagation characteristics of sound waves at the entrance need to be considered. The angle between the sound wave propagation direction and the entrance normal determines whether the sound wave can efficiently enter the acoustic cavity. A threshold of 30 degrees is typically used as the default angle of incidence. In acoustic simulation analysis, the finite element method is used to model the sound wave propagation path. For example, a sound wave with a frequency of 1000 Hz, after emanating from the driver unit, first passes through a sound conduit and enters the spiral tapered acoustic cavity. The sound conduit has a diameter of 3 mm and a length of 5 mm. Upon entering the acoustic cavity, if the angle of incidence is 25 degrees, which is less than the preset threshold of 30 degrees, the sound wave can effectively enter the cavity and propagate along the spiral path. Sound waves attenuate as they propagate within an acoustic cavity, primarily due to viscous losses and thermal conduction losses. The acoustic performance of the acoustic cavity can be optimized by adjusting the geometric parameters of the spiral tapered structure. For example, adjusting the spiral angle from the initial 75 degrees to 80 degrees can reduce the energy loss of the sound wave during propagation by approximately 15%. At the same time, adjusting the tapering ratio from 1.5 to 1.8 can make the sound wave propagation path smoother, reducing reflection and scattering during propagation. The acoustic performance parameters of the acoustic cavity include the sound pressure level response curve, phase response, and harmonic distortion. The optimized acoustic cavity structure can increase the sound pressure level at a frequency of 1000 Hz by approximately 3 decibels and reduce harmonic distortion by approximately 0.5%. When the sound wave incident angle was recalculated, the adjusted incident angle was found to be 22 degrees, which is more ideal than the previous 25 degrees, further improving the efficiency of sound waves entering the acoustic cavity. In practical applications, the optimization of the acoustic cavity structure also needs to consider material properties and processing technology. Taking polycarbonate as an example, its excellent acoustic and processing properties allow for the creation of complex spiral tapered structures through injection molding. By adjusting mold temperature and injection pressure, the smoothness of the acoustic cavity's inner wall can be ensured, minimizing scattering losses during sound wave propagation. The resulting spiral tapered structure not only effectively guides sound wave propagation but also provides a superior acoustic experience.

[0033] S105: If the sound wave incident angle exceeds a preset range, adjust the entrance diameter parameter of the logarithmic spiral model and recalculate the sound wave incident angle until the matching requirement of the drive unit is met.

[0034] Obtain a current value of the sound wave incident angle, and determine whether the current value exceeds a preset range value; if the current value exceeds the preset range value, adjust the inlet diameter parameter value of the logarithmic spiral model to obtain an adjusted inlet diameter parameter value; use the adjusted inlet diameter parameter value to recalculate the sound wave incident angle to obtain a recalculated sound wave incident angle; determine whether the recalculated sound wave incident angle meets a preset drive unit matching requirement; if the recalculated sound wave incident angle does not meet the preset drive unit matching requirement, cyclically adjust the inlet diameter parameter value and recalculate the sound wave incident angle until it meets the preset drive unit matching requirement; if the recalculated sound wave incident angle meets the preset drive unit matching requirement, determine a final inlet diameter parameter value of the logarithmic spiral model; based on the final inlet diameter parameter value, output a sound wave incident angle calculation result that meets the preset drive unit matching requirement.

[0035] Specifically, the range of sound wave incident angles is often closely related to the acoustic characteristics of the driver unit. For example, in headphone acoustic cavity design, the sound wave incident angle should be controlled between 0 and 30 degrees to ensure efficient sound wave entry and a well-defined sound field distribution. A larger incident angle can lead to increased sound wave reflection, resulting in increased sound energy loss and impacting sound reproduction quality. Adjusting the entrance diameter parameter of the logarithmic spiral model requires consideration of multiple factors. For high-end in-ear headphones, for example, an initial entrance diameter of 6 mm may result in a sound wave incident angle of 40 degrees, exceeding the preset 30-degree range. In this case, the entrance diameter should be gradually adjusted, increasing by 0.5 mm at a time, until the incident angle falls within the appropriate range. In practice, increasing the entrance diameter to 8 mm can reduce the incident angle to around 25 degrees, meeting design requirements. The matching requirements between the sound wave incident angle and the driver unit are reflected in multiple aspects. Modern dynamic drivers typically require an entrance angle between 20 and 30 degrees, while piezoelectric drivers can accommodate a wider range of entrance angles. For example, a dynamic headphone exhibits optimal frequency response flatness and minimal distortion at an incident angle of 28 degrees. Exceeding this range can lead to reduced high-frequency response or prominent mid-range frequencies. During the cyclic adjustment process, a reasonable adjustment step size must be established. For example, in a miniature headphone design, the initial entrance diameter is 5 mm and the entrance angle is 35 degrees. Using an adjustment step size of 0.3 mm, after four adjustments, the entrance diameter increases to 6.2 mm and the entrance angle decreases to 26 degrees, achieving the optimal match with the 9 mm dynamic driver. The final entrance diameter parameters must also meet manufacturing process requirements. In actual production, if the final calculated entrance diameter is 7.83 mm, it can be rounded to 7.8 mm to account for machining accuracy and process limitations. This subtle adjustment typically does not significantly affect the sound wave incident angle, but it can significantly improve production efficiency and yield. Verification of the output results is equally important. In an actual case, the optimized incident angle was 23 degrees. Acoustic testing found that at this angle, the frequency response curve fluctuation of the headphones in the range of 20 Hz to 20,000 Hz remained within plus or minus three decibels, with small sound coloration and accurate sound field positioning, fully confirming the reliability of the optimization results.

[0036] S106. Add inner wall scale protrusion features to the acoustic cavity geometry model, with a protrusion height of 0.1 mm and a spacing of 0.3 mm. Simulate the diffusion effect of sound waves in the cavity based on computational fluid dynamics.

[0037] Acquire three-dimensional data information of the acoustic cavity geometric model, and perform feature extraction on the inner wall surface of the acoustic cavity geometric model; if the feature extraction result includes a scale protrusion structure, obtain the protrusion height and spacing parameters of the scale protrusion structure; reconstruct the inner wall surface morphology of the acoustic cavity model according to the geometric feature parameters of the scale protrusion structure; adopt computational fluid dynamics methods to establish a mathematical model of the diffusion of sound waves in the acoustic cavity model; set the inner wall boundary conditions of the acoustic cavity model in the mathematical model, and the inner wall boundary conditions include the geometric features of the scale protrusion structure; solve the diffusion process of the sound wave in the acoustic cavity model by a numerical calculation method, and obtain the diffusion effect data of the sound wave in the acoustic cavity model with the scale protrusion structure features.

[0038] Specifically, 3D data analysis of the acoustic cavity geometry model first requires accurate geometric information of the cavity's inner surface. For example, a high-precision 3D scanner can be used to collect a point cloud of the inner wall data, achieving a scanning accuracy of 0.01 mm. During feature extraction, the distribution characteristics of the scaly protrusions are emphasized. Assume that the inner wall surface is composed of regularly arranged scaly protrusions, each ranging in height from 0.5 to 1 mm, with spacing of approximately 5 mm between adjacent protrusions. This unique surface morphology is similar to structures commonly found in bioacoustic systems, such as the microstructure of owl wings. When reconstructing the inner wall surface morphology, the effect of the scaly protrusions on sound wave propagation must be considered. By establishing a parametric geometric model, the protrusions are simplified into regular conical or hemispherical units. For example, if the protrusions are conical, they can be set with a base diameter of 1 mm and a height of 0.8 mm, distributed in a hexagonal array. This structure effectively reduces sound wave reflection and increases sound energy absorption. Setting boundary conditions is crucial in numerical simulations of sound wave diffusion. The acoustic impedance of the inner wall surface depends on the material properties. If a porous material is used, its acoustic impedance may be around 40,000 reels. The presence of scale protrusions changes the way sound waves interact with the boundary, producing a microscopic scattering effect. In practical applications, this structure can reduce directional reflection of sound waves and improve acoustic diffusion. Numerical calculations use the finite element method to solve the acoustic wave equation, and the meshing must fully consider the characteristic dimensions of the scale structure. For example, a 20 kHz sound wave has a wavelength of approximately 17 mm, requiring a mesh size no larger than one-sixth of the wavelength, or less than 3 mm. Calculation results show that an inner wall with scale protrusions can significantly alter the sound field distribution. The sound pressure level distribution becomes more uniform, the reverberation time is shortened by approximately 15%, and the sound energy decay curve is smoother. This structure has important applications in the acoustic design of venues such as concert halls and recording studios. The scale structure's effects vary across different frequency ranges. At low frequencies (e.g., 100 to 500 Hz), sound absorption is enhanced primarily by increasing surface area. In the mid- to high-frequency bands (e.g., 1,000 to 5,000 Hz), scattering is the primary method for achieving uniform distribution of the sound field. By rationally designing the geometric parameters of the scale structure, it is possible to directionally control sound waves in specific frequency bands, achieving the desired acoustic effect.

[0039] S107. If the simulation results show that the sound wave diffuses unevenly, the geometric parameters of the scale protrusions are adjusted and the fluid dynamics calculation is re-performed until the sound wave diffuses evenly in the cavity and there is no significant reflection within the predetermined frequency range.

[0040] Based on the results of the sound wave diffusion simulation, determine whether the degree of diffusion uniformity meets the preset conditions. If the diffusion is uneven, obtain the current geometric parameters of the scale protrusions and adjust them. Use the adjusted geometric parameters to re-calculate the fluid mechanics to obtain new sound wave diffusion simulation results. Based on the new simulation results, analyze the diffusion uniformity of the sound wave in the cavity and the reflection intensity within the predetermined frequency range. If the sound wave diffusion is still uneven or the reflection intensity exceeds the preset threshold, adjust the geometric parameters again and repeat the calculation process. Through multiple iterative calculations, determine the optimal combination of geometric parameters. Finally, obtain the optimized result that satisfies the uniform diffusion of the sound wave and no significant reflection.

[0041] Specifically, the uniformity of sound wave diffusion can be assessed by measuring the sound pressure level distribution. Multiple measurement points are set up within the cavity, and the changes in sound pressure over time are recorded. For example, twenty measurement points are evenly spaced within the cavity. If the sound pressure level deviation at each point exceeds a preset threshold of three decibels, the diffusion is determined to be uneven. Adjustment of the geometric parameters of the scale projections requires consideration of both height and spacing. If the sound pressure in a certain area is too high, the scale height in that area can be appropriately increased to enhance the scattering effect, for example, from 0.1 mm to 0.15 mm. If the sound pressure distribution exhibits significant periodic fluctuations, the scale spacing can be adjusted, for example, from 0.3 mm to 0.25 mm to break up the periodic distribution. In fluid dynamics calculations, attention must be paid to the behavior of sound waves at different frequencies. For example, when the incident sound wave frequency is 1,000 Hz, a peak sound pressure of five decibels is observed in a certain area of ​​the cavity using the original scale parameters. By adjusting the scale height in that area to 0.12 mm and the spacing to 0.28 mm, the peak sound pressure is reduced to within three decibels. Controlling the intensity of sound wave reflection is crucial to preventing the formation of standing waves. In practical applications, a threshold of no more than 0.3 can be set for the reflection coefficient. When the reflection coefficient reaches 0.4 at a specific location, the geometric shape of the scales needs to be comprehensively considered. By designing the scale edges with a gradual transition pattern, directional reflection of sound waves can be effectively reduced. The optimization process is iterative, with the improvement in the sound pressure distribution observed after each iteration. A typical optimization process may require five to six iterations. For example, after the first round of adjustments, the sound pressure deviation may be reduced from 5dB to 4dB, then to 3.5dB in the second round, until it is finally controlled within the 2dB range. Each iteration also requires checking the sound wave response in different frequency bands to ensure that the desired effect is achieved within the target frequency range. The final optimization result should meet the requirements for both sound pressure uniformity and reflection control. In one actual case, the optimized scale structure achieved a sound pressure level deviation within ±1.5dB in the range of 500Hz to 2000Hz, with a maximum reflection coefficient of no more than 0.25, achieving the expected acoustic performance target. This optimized structure can provide an important reference for the design of acoustic equipment.

[0042] S108. Import the final optimized acoustic cavity model into the 3D printing system, use titanium alloy material, and manufacture the acoustic cavity entity through precision molding technology to complete the design of the in-ear headphone cavity based on the bionic cochlear structure.

[0043] Obtain the optimized acoustic cavity model data, perform parametric modeling on the bionic cochlear structure, and obtain a three-dimensional model. Generate a file format recognizable by 3D printing based on the three-dimensional model. Use titanium alloy material as the manufacturing raw material, set the precision molding process parameters, and obtain the printing parameters. Import the 3D printing file into the printing system and start the manufacturing process. Obtain real-time data during the printing process to determine whether the molding accuracy meets the preset threshold. If the accuracy does not meet the preset threshold, adjust the process parameters and restart the printing process; if the accuracy meets the preset threshold, generate the final earphone cavity entity, and complete the design based on the bionic cochlear structure.

[0044] Specifically, the parametric modeling of the bionic cochlear structure must be adapted from the basic structural characteristics of the human cochlea. When modeling the spiral tube, Bezier curves can be used to control the twisting path. The radius gradient of each turn is set to 0.5 mm, and the total number of spiral turns is set to two and a half. This better simulates the spiral shape of the human ear. Regarding the structural parameter setting, the cavity adopts a quasi-elliptical cross-section with a major axis of four millimeters and a minor axis of three millimeters to ensure smooth sound wave transmission. The generation of 3D printing file formats must consider printer compatibility. Common formats such as point cloud data must be converted to a triangular facet format, with each triangular facet having a side length of no more than 0.1 mm to ensure surface refinement. Regarding titanium alloy material selection, spherical powder with a particle size between 15 and 45 microns is recommended to ensure flowability during printing and sintered density. The precision molding process parameters directly impact the quality of the final product. The laser power can be set between 180 and 200 watts, the scanning speed between 800 and 1,000 millimeters per second, and the layer thickness set to 30 microns. This combination of parameters ensures sufficient material melting and prevents overburning. During the printing process, the overlap ratio for each scan layer is set to 30%, effectively preventing poor interlayer bonding. The real-time monitoring system focuses on two key aspects: first, the morphological characteristics of the melt pool. A high-speed camera captures the melt pool dimensions. When the melt pool diameter exceeds a preset value by 10%, the laser power is adjusted immediately. Second, the flatness of the built layer is monitored in real time using a laser rangefinder. Deviations exceeding 50 microns require compensation. A closed-loop control strategy is used for process parameter adjustment. If the density of a specific area is detected to be less than 99.5%, the energy density in that area can be appropriately increased by reducing the scanning speed by 5% to 10%. If the surface roughness exceeds the specified value, the scanning path needs to be optimized. A checkerboard scanning strategy can be used, with each small area set to a side length of 5 mm. The final earphone cavity requires post-processing. First, a stress relief heat treatment is performed at 600 degrees Celsius for two hours. Next, a surface treatment is performed using sandblasting with 120-mesh aluminum oxide grit to achieve a uniform surface texture. This ensures good acoustic performance and service life of the product.

[0045] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure, characterized in that: The method comprises the following steps: S101, obtaining a mathematical model of a logarithmic spiral, and constructing a three-dimensional geometric model of a spiral tapered acoustic cavity structure based on parameters of an inlet diameter of 6 mm, an outlet diameter of 3.2 mm, and a spiral angle of 15°; S102, performing finite element analysis on the acoustic cavity geometric model, calculating the propagation path and pressure distribution of the sound wave in the cavity, and determining whether the sound wave forms a standing wave within a predetermined frequency range; S103. If the finite element analysis results show the existence of standing waves, adjust the spiral angle parameters of the logarithmic spiral model and recalculate the sound wave propagation characteristics in the model until the standing wave phenomenon is suppressed; S104. Calculate the incident angle of the sound wave at the entrance based on the optimized spiral tapered structure model and the acoustic characteristics of the headphone driver unit to determine whether the sound wave can efficiently enter the acoustic cavity. S105: If the sound wave incident angle exceeds the preset range, adjust the inlet diameter parameter of the logarithmic spiral model and recalculate the sound wave incident angle until the matching requirement of the drive unit is met; S106. Add inner wall scale protrusion features to the acoustic cavity geometry model, with a protrusion height of 0.1 mm and a spacing of 0.3 mm, and simulate the diffusion effect of sound waves in the cavity based on computational fluid dynamics; S107. If the simulation results show that the sound wave diffusion is uneven, adjust the geometric parameters of the scale protrusions and re-perform the fluid dynamics calculation until the sound wave diffuses evenly in the cavity and there is no significant reflection within the predetermined frequency range; S108. Import the final optimized acoustic cavity model into the 3D printing system, use titanium alloy material, and manufacture the acoustic cavity entity through precision molding technology to complete the design of the in-ear headphone cavity based on the bionic cochlear structure.

2. The method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure according to claim 1, characterized in that: The S101 includes: Obtain the inlet diameter and outlet diameter of the acoustic cavity, determine the proportional relationship between the two, and obtain the tapering ratio of the spiral structure; According to the proportional relationship, a logarithmic spiral equation is used to construct a three-dimensional mathematical model of the spiral, wherein the mathematical model uses the inlet diameter, the outlet diameter and the spiral angle as input parameters; According to the mathematical model, three-dimensional point cloud data of the spiral is generated to construct the spatial structure of the spiral; Obtaining a thickness parameter of the acoustic cavity wall, applying the thickness parameter to the spiral spatial structure, and generating a three-dimensional geometric model of the acoustic cavity spiral tapered structure; Using a finite element analysis method to mesh the three-dimensional geometric model and calculate the flow field distribution inside the acoustic cavity; If the flow field distribution meets the preset conditions, outputting the three-dimensional geometric model; If the flow field distribution does not meet the preset conditions, the helix angle is adjusted and the mathematical model is reconstructed until a three-dimensional geometric model meeting the preset conditions is obtained.

3. The method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure according to claim 1, characterized in that: The S102 includes: Acquiring an acoustic cavity model including geometric parameters, wherein the acoustic cavity model includes boundary conditions and material properties; Using a finite element analysis method, grid cells are divided on the acoustic cavity model to generate a calculation domain; According to the sound wave propagation equation, a sound pressure calculation equation is established at the node of each grid unit; By solving the sound pressure calculation equation group, a sound pressure distribution diagram in the sound cavity is obtained; Extracting node values ​​from the sound pressure distribution diagram and calculating the sound pressure amplitude at each frequency; If the sound pressure amplitude at a certain frequency presents a periodic distribution within the preset frequency range, it is determined that a standing wave is formed at this frequency; The frequency range in which the standing wave is formed is compared with the preset frequency range to obtain an analysis result of the standing wave formation situation.

4. The method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure according to any one of claims 1 to 3, characterized in that: The S103 includes: Obtaining finite element analysis results, and determining whether there is a standing wave in the finite element analysis results; If the standing wave exists, extracting the spiral angle parameter of the logarithmic spiral model and using the spiral angle parameter as an adjustment target; According to a preset spiral angle threshold range, the spiral angle parameter is adjusted using a gradient descent algorithm to obtain an adjusted spiral angle parameter; Substituting the adjusted helix angle parameter into the sound wave propagation characteristic calculation model, recalculating the sound wave propagation characteristic, and obtaining an updated sound field distribution; Using a support vector machine algorithm to analyze the updated sound field distribution to determine whether the standing wave phenomenon is suppressed; If the standing wave phenomenon is not completely suppressed, the spiral angle parameter is repeatedly adjusted and the acoustic wave propagation characteristics are recalculated until the standing wave phenomenon is completely suppressed.

5. The method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure according to any one of claims 1 to 3, characterized in that: The S104 includes: Obtaining geometric parameters of the optimized spiral tapered structure model, and combining them with acoustic characteristic parameters of the headphone driver unit to obtain the propagation direction of the sound wave at the entrance; Calculating the incident angle of the sound wave at the entrance according to the angle between the sound wave propagation direction and the normal line at the entrance; If the incident angle is less than a preset threshold, it is determined that the sound wave can efficiently enter the acoustic cavity; Using an acoustic simulation algorithm to simulate the propagation path of the sound wave in the acoustic cavity; analyzing the attenuation of the sound wave in the acoustic cavity according to the propagation path of the sound wave in the acoustic cavity; According to the sound wave attenuation, the geometric parameters of the spiral tapered structure model are adjusted to obtain an optimized spiral tapered structure model, wherein the optimized spiral tapered structure model is used to optimize the acoustic performance of the sound cavity; Acquiring acoustic performance parameters of the optimized acoustic cavity, and recalculating the incident angle of the sound wave at the entrance according to the acoustic performance parameters; If the recalculated incident angle meets the preset conditions, it is determined that the optimization of the spiral tapered structure model is completed.

6. The method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure according to any one of claims 1 to 3, characterized in that: The S105 includes: Obtaining a current value of the sound wave incident angle, and determining whether the current value exceeds a preset range; If the current value exceeds the preset range, adjusting the inlet diameter parameter value of the logarithmic spiral model to obtain an adjusted inlet diameter parameter value; Recalculating the sound wave incident angle using the adjusted inlet diameter parameter value to obtain a recalculated sound wave incident angle; Determining whether the recalculated sound wave incident angle meets a preset drive unit matching requirement; If the recalculated sound wave incident angle does not meet the preset drive unit matching requirement, the inlet diameter parameter value is cyclically adjusted and the sound wave incident angle is recalculated until the preset drive unit matching requirement is met; If the recalculated sound wave incident angle meets the preset drive unit matching requirement, determining a final inlet diameter parameter value of the logarithmic spiral model; According to the final inlet diameter parameter value, a calculation result of the sound wave incident angle that meets the preset drive unit matching requirement is output.

7. The method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure according to any one of claims 1 to 3, characterized in that: The S106 includes: Acquiring three-dimensional data information of a vocal cavity geometric model, and performing feature extraction on an inner wall surface of the vocal cavity geometric model; If the feature extraction result includes a scale-shaped protrusion structure, obtaining protrusion height and spacing parameters of the scale-shaped protrusion structure; Reconstructing the inner wall surface morphology of the acoustic cavity model according to the geometric characteristic parameters of the scale-shaped protrusion structure; A mathematical model of the diffusion of sound waves in the acoustic cavity model is established using a computational fluid dynamics method; Setting inner wall boundary conditions of the acoustic cavity model in the mathematical model, wherein the inner wall boundary conditions include geometric features of the scale-shaped protrusion structure; The diffusion process of the sound wave in the acoustic cavity model is solved by a numerical calculation method, and the diffusion effect data of the sound wave in the acoustic cavity model having the scale-protrusion structural feature is obtained.

8. The method for optimizing the acoustic cavity of an in-ear headphone based on a bionic cochlear structure according to any one of claims 1 to 3, characterized in that: The S107 includes: According to the acoustic wave diffusion simulation results, determine whether the diffusion uniformity meets the preset conditions; If the diffusion is uneven, obtain the current scale protrusion geometric parameters for adjustment; The adjusted geometric parameters are used to re-calculate the fluid dynamics and obtain new simulation results of the acoustic wave diffusion. Based on the new simulation results, the diffusion uniformity of the sound wave in the cavity and the reflection intensity within the predetermined frequency range are analyzed; If the sound wave diffusion is still uneven or the reflection intensity exceeds the preset threshold, the geometric parameters are adjusted again and the calculation process is repeated; Determine the optimal geometric parameter combination through multiple iterative calculations; Finally, an optimized result is obtained that satisfies the uniform diffusion of sound waves and has no significant reflection.

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