Sound box airflow noise reduction effect evaluation device and evaluation method

Abstract

The invention provides a sound box airflow noise reduction effect evaluation device and evaluation method, and relates to the technical field of sound box acoustics. The device comprises a sensitivity acquisition unit, a noise acquisition unit and a signal processing unit. The sensitivity acquisition unit acquires sound pressure signals radiated by the tested sound box before and after noise reduction; the signal processing unit performs sensitivity calibration on the tested sound box according to the sound pressure signal; the noise acquisition unit acquires airflow noise signals radiated by the sound outlet holes before and after noise reduction; and the signal processing unit performs frequency domain transformation on the airflow noise signal to obtain noise spectrums before and after noise reduction, determines the average reduction amount of the sound pressure level of the airflow noise according to the spectrums, and generates a quantitative evaluation result of the noise reduction effect according to the average reduction amount. According to the invention, the double acquisition units are arranged, the signal processing unit is introduced to carry out calibration and spectral analysis, and the quantitative index, namely the average reduction amount of the sound pressure level of the airflow noise, is output, so that the individual difference of subjective listening evaluation is effectively overcome, and the reliability of an evaluation result is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of loudspeaker acoustics, in particular to a loudspeaker air flow noise reduction effect evaluation device and method. BACKGROUND

[0002] As the core equipment of audio playback systems, loudspeakers are widely used in home theaters, smart speakers, car audio systems, professional recording studios, and portable Bluetooth speakers. In home theater systems, loudspeakers need to provide immersive low-frequency experiences to enhance the viewing atmosphere. In smart speakers, the low-frequency response is directly related to the clarity of voice interaction. In car audio systems, low-frequency extension capability is an important indicator of improving driving comfort. Designs such as bass reflex ports, acoustic labyrinths, acoustic metamaterials, and bandpass enclosures use the air coupling between the cabinet and the bass reflex port to significantly improve the low-frequency sound pressure level and frequency response range through the Helmholtz resonance principle, becoming the key technology for small-size loudspeakers to achieve high-quality low-frequency output. However, these designs, while enhancing low-frequency performance, also bring significant air flow noise problems. When the loudspeaker produces large-amplitude motion under low-frequency signal excitation, the air inside and outside the cabinet flows at high speed through the bass reflex port. If the air flow velocity exceeds the critical value, the air flow in the port changes from laminar flow to turbulent flow, causing random pressure fluctuations, which are manifested as "whistling" sounds, "wind noise", or low-frequency distortion. This type of noise seriously degrades the clarity of sound quality and listening comfort. In portable speakers with limited cabinet volume, the trade-off between low-frequency performance and air flow noise becomes particularly prominent due to the small design space. To overcome the above air flow noise problems, researchers need to try various noise reduction schemes, such as optimizing the geometry of the bass reflex port, adding damping materials in the acoustic path, or applying new metamaterial structures. Therefore, accurate evaluation of the noise reduction effect is crucial in this optimization process.

[0003] In related technologies, the evaluation of noise reduction effect mainly relies on subjective listening methods. Specifically, researchers play specific low-frequency signals (such as single-frequency sweep or music clips), and tuning experts directly listen to the loudspeaker output sound, judge the intensity of air flow noise and listening comfort based on experience, and give noise reduction effect evaluation results based on listening. However, there are cases where the noise reduction effect evaluation is unreliable. SUMMARY

[0004] The present application provides a loudspeaker air flow noise reduction effect evaluation device and method to improve the problem of unreliable noise reduction effect evaluation in related technologies.

[0005] In a first aspect, the application provides a sound box airflow noise reduction effect evaluation device, which comprises a sensitivity acquisition unit, a noise acquisition unit and a signal processing unit, wherein:

[0006] The sensitivity acquisition unit is configured to acquire a first sound pressure signal and a second sound pressure signal respectively radiated by the measured sound box before and after noise reduction.

[0007] The signal processing unit is electrically connected with the noise acquisition unit and the sensitivity acquisition unit, and is configured to calibrate the sensitivity of the measured sound box according to the first sound pressure signal and the second sound pressure signal, so as to ensure that the sensitivities of the measured sound box before and after noise reduction are consistent.

[0008] The noise acquisition unit is configured to acquire a first airflow noise time domain signal and a second airflow noise time domain signal respectively radiated by the sound hole of the measured sound box before and after noise reduction.

[0009] The signal processing unit is further configured to perform frequency domain transformation on the first airflow noise time domain signal and the second airflow noise time domain signal to obtain a noise spectrum before noise reduction and a noise spectrum after noise reduction, and determine an average airflow noise sound pressure level reduction in a set frequency range according to the noise spectrum before noise reduction and the noise spectrum after noise reduction, and generate a quantitative evaluation result of the noise reduction effect based on the average airflow noise sound pressure level reduction.

[0010] In a possible implementation, when the signal processing unit is used to determine the average airflow noise sound pressure level reduction in the set frequency range, the average airflow noise sound pressure level reduction satisfies the following formula:

[0011]

[0012] wherein, is the average airflow noise sound pressure level reduction; is the excitation frequency of the single-frequency excitation signal; is the highest frequency in the set frequency range; is the number of frequency points in the set frequency range; is the noise spectrum before noise reduction, is the noise spectrum after noise reduction.

[0013] In a possible implementation, the sensitivity acquisition unit comprises a first microphone, and the first microphone is arranged on the axis of the loudspeaker unit of the measured sound box.

[0014] In a possible implementation, the distance between the first microphone and the loudspeaker unit is 1 meter.

[0015] In a possible implementation, the noise collecting unit comprises a second microphone, and the second microphone is arranged on the axis of the sound hole of the measured speaker.

[0016] In a possible implementation, the distance L between the second microphone and the sound hole satisfies: 0.01 meters≤L≤2 meters.

[0017] In a possible implementation, the distance L between the second microphone and the sound hole is 0.5 meters.

[0018] In a possible implementation, the second microphone is additionally provided with a windproof ball.

[0019] In a possible implementation, the speaker airflow noise reduction effect evaluation device further comprises a first support for supporting the measured speaker, a second support for supporting the sensitivity collecting unit, and a third support for supporting the noise collecting unit.

[0020] In a second aspect, the present application provides a speaker airflow noise reduction effect evaluation method, which is applied to a signal processing unit in the speaker airflow noise reduction effect evaluation device of any one of the first aspect, and the speaker airflow noise reduction effect evaluation method comprises:

[0021] obtaining a first sound pressure signal and a second sound pressure signal respectively radiated by the measured speaker before and after noise reduction;

[0022] performing sensitivity calibration on the measured speaker according to the first sound pressure signal and the second sound pressure signal, so as to ensure that the sensitivities of the measured speaker before and after noise reduction are consistent;

[0023] obtaining a first airflow noise time domain signal and a second airflow noise time domain signal respectively radiated by the sound hole of the measured speaker before and after noise reduction;

[0024] performing frequency domain transformation on the first airflow noise time domain signal and the second airflow noise time domain signal to obtain a noise spectrum before noise reduction and a noise spectrum after noise reduction, and determining an average airflow noise sound pressure level reduction in a set frequency range according to the noise spectrum before noise reduction and the noise spectrum after noise reduction, and generating a quantitative evaluation result of the noise reduction effect based on the average airflow noise sound pressure level reduction.

[0025] In a third aspect, the present application provides a signal processing unit, comprising: a processor, and a memory in communication connection with the processor;

[0026] the memory is used for storing computer execution instructions;

[0027] the processor is used for executing the computer execution instructions stored in the memory, so as to realize the method of the second aspect.

[0028] In a fourth aspect, the present application provides a computer readable storage medium, which stores computer execution instructions, and the computer execution instructions are used to implement the method of the second aspect when executed.

[0029] In a fifth aspect, the present application provides a computer program product, which comprises a computer program, and the computer program is used to implement the method of the second aspect when executed.

[0030] The sound box air flow noise reduction effect evaluation device and method provided by the present application comprise a sensitivity acquisition unit, a noise acquisition unit and a signal processing unit. The sensitivity acquisition unit is used to acquire first sound pressure signals and second sound pressure signals respectively radiated by the measured sound box before and after noise reduction. The signal processing unit is electrically connected with the noise acquisition unit and the sensitivity acquisition unit, and is used to calibrate the sensitivity of the measured sound box according to the first sound pressure signals and the second sound pressure signals, so as to ensure that the sensitivities of the measured sound box before and after noise reduction are consistent. The noise acquisition unit is used to acquire first air flow noise time domain signals and second air flow noise time domain signals respectively radiated by the sound hole of the measured sound box before and after noise reduction. The signal processing unit is further used to perform frequency domain transformation on the first air flow noise time domain signals and the second air flow noise time domain signals, to obtain noise frequency spectrums before and after noise reduction, and to determine an average air flow noise sound pressure level reduction in a set frequency range according to the noise frequency spectrums before and after noise reduction, and to generate a quantitative evaluation result of the noise reduction effect based on the average air flow noise sound pressure level reduction.

[0031] The present application overcomes the fuzziness and individual difference of the traditional subjective listening evaluation by setting independent sensitivity acquisition units and noise acquisition units and introducing a signal processing unit for automatic sensitivity calibration and spectrum analysis, and finally outputs the quantitative index of "average air flow noise sound pressure level reduction", which changes the qualitative judgment of the noise reduction effect depending on human ear experience into accurate measurement depending on objective data, and significantly improves the reliability, consistency and repeatability of the evaluation result, thereby significantly improving the research and development efficiency of sound box air flow noise problem troubleshooting and noise reduction scheme optimization. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.

[0033] Figure 1 A structural schematic diagram of the sound box air flow noise reduction effect evaluation device provided for the exemplary embodiments of the present application;

[0034] Figure 2 A schematic diagram of the air flow noise test spectrum provided for the exemplary embodiments of the present application;

[0035] Figure 3 The arrangement schematic diagram of the sound box air flow noise reduction effect evaluation device with the phase inverter tube facing forward is provided for the exemplary embodiments of the present application;

[0036] Figure 4 The arrangement schematic diagram of the sound box air flow noise reduction effect evaluation device with the phase inverter tube facing backward is provided for the exemplary embodiments of the present application;

[0037] Figure 5 The arrangement schematic diagram of the sound box air flow noise reduction effect evaluation device with the phase inverter tube facing left / right is provided for the exemplary embodiments of the present application;

[0038] Figure 6 The arrangement schematic diagram of the sound box air flow noise reduction effect evaluation device with the phase inverter tube facing downward is provided for the exemplary embodiments of the present application;

[0039] Figure 7 The flowchart of the sound box air flow noise reduction effect evaluation method is provided for the exemplary embodiments of the present application;

[0040] Figure 8 The structure schematic diagram of the signal processing unit is provided for the exemplary embodiments of the present application.

[0041] In the figure, 10 is the sound box air flow noise reduction effect evaluation device; 11 is the sensitivity collection unit; 12 is the noise collection unit; 13 is the signal processing unit; 131 is the processor; 132 is the memory; 133 is the communication interface; 14 is the sound box to be measured; 141 is the box body; 142 is the loudspeaker unit; 143 is the sound hole; 15 is the windproof ball; 16 is the first support; 17 is the second support; 18 is the third support.

[0042] The specific embodiments of the present application have been shown in the above-mentioned figures, and will be described in more details hereinafter. These figures and textual descriptions are not intended to limit the scope of the concept of the present application by any means, but to illustrate the concept of the present application to the person skilled in the art by referring to the specific embodiments. DETAILED DESCRIPTION

[0043] The exemplary embodiments will be described in detail herein, and the examples are shown in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims.

[0044] The terms "first", "second", and the like in the description and in the claims of the present application are used for distinguishing between similar objects and not necessarily for describing a specific sequential or chronological order. It is to be understood that the use of the terms so construed can be interchanged, such that, for example, embodiments of the present application described herein can operate in other sequences than the one illustrated or described herein. Further, the terms "comprises", "comprising", "includes", "including" and the like are to be construed open-ended, meaning that they are used to describe a process, system, product or article of manufacture that comprises, but is not limited to, those elements expressly listed after such terms in this document. In other words, when the specification states a process, system, product or article of manufacture that comprises elements A, B and C, the process, system, product or article of manufacture can also comprise other elements not expressly listed or the elements A, B and C can exist in different formats.

[0045] It should be noted that the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of related data need to comply with relevant laws, regulations and standards, and provide corresponding operation portal for user to choose authorization or refusal.

[0046] In the related art, when relying on subjective listening to evaluate the noise reduction effect, the evaluation result is completely based on the personal auditory perception and experience judgment of the tuning expert, resulting in that the evaluation result is seriously subject to individual auditory sensitivity differences, listening experience, physical and mental state at the time, and personal preferences and other uncertain factors. Such an evaluation mechanism relying on "people" rather than "objective standards" often leads to a lack of unified quantitative benchmark for the evaluation result, poor reproducibility, and easy misjudgment and inconsistent conclusions in evaluation by different personnel or at different time points, so that the final noise reduction effect evaluation result lacks reliability and comparability, and cannot provide stable and reliable decision basis for objective comparison and optimization of technical solutions.

[0047] To solve the above problems, the embodiment of the present application provides a kind of sound box airflow noise reduction effect evaluation scheme, by constructing a set of objective quantitative evaluation device, effectively solve the inherent defects of traditional subjective listening evaluation, the device adopts dual-channel acquisition and two-stage processing architecture, specifically, by sensitivity calibration ensure that the sound pressure output consistency of the measured sound box before and after noise reduction, exclude non-related variable interference;Further, the time domain signal of airflow noise is transformed and spectrum analyzed in frequency domain, and then the average reduction of airflow noise sound pressure level in the set frequency range is determined, to obtain a unique and reproducible quantitative evaluation value, so that the evaluation of noise reduction effect is changed from relying on human ear experience to objective data, which significantly improves the accuracy and efficiency of evaluation, and further significantly improves the reliability of noise reduction effect evaluation, and provides stable and reliable decision basis for objective comparison and optimization of technical solutions.

[0048] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes can not be described again in some examples. The embodiments of the present application will be described below with reference to the drawings.

[0049] Figure 1 A structural schematic diagram of an audio box airflow noise reduction effect evaluation device provided for an exemplary embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, the audio box airflow noise reduction effect evaluation device 10 includes a sensitivity acquisition unit 11, a noise acquisition unit 12, and a signal processing unit 13. Figure 1

[0050] The sensitivity acquisition unit 11 is configured to acquire a first sound pressure signal and a second sound pressure signal respectively radiated by a measured audio box before and after noise reduction.

[0051] The signal processing unit 13 is electrically connected to the noise acquisition unit 12 and the sensitivity acquisition unit 11, and is configured to calibrate the sensitivity of the measured audio box according to the first sound pressure signal and the second sound pressure signal, so as to ensure that the sensitivities of the measured audio box before and after noise reduction are consistent.

[0052] The noise acquisition unit 12 is configured to acquire a first airflow noise time domain signal and a second airflow noise time domain signal respectively radiated by a sound hole of a measured audio box before and after noise reduction.

[0053] The signal processing unit 13 is further configured to perform frequency domain transformation on the first airflow noise time domain signal and the second airflow noise time domain signal to obtain a noise spectrum before noise reduction and a noise spectrum after noise reduction, and determine an average airflow noise sound pressure level reduction in a set frequency range according to the noise spectrum before noise reduction and the noise spectrum after noise reduction, and generate a quantitative evaluation result of the noise reduction effect based on the average airflow noise sound pressure level reduction.

[0054] ​The sound hole refers to an opening on the sound box for air exchange between the inside and outside of the box, and common forms include a reverse phase tube, an acoustic labyrinth outlet, and a radiation port of an acoustic metamaterial structure. The core responsibility of the sensitivity acquisition unit 11 is to monitor whether the overall output capability of the sound box as a sound source changes before and after the implementation of the noise reduction scheme. Specifically, the sensitivity acquisition unit 11 is configured to acquire a first sound pressure signal radiated by the sound box before noise reduction and a second sound pressure signal radiated by the sound box after noise reduction. The core responsibility of the noise acquisition unit 12 is to capture the noise caused by the high-speed airflow generated by the sound hole of the sound box. Specifically, the noise acquisition unit 12 is configured to acquire a first airflow noise time-domain signal radiated by the sound hole before noise reduction and a second airflow noise time-domain signal radiated by the sound hole after noise reduction. The signal processing unit 13 is electrically connected to the sensitivity acquisition unit 11 and the noise acquisition unit 12 (for example, through a data acquisition card and a cable), receives the signals transmitted by the sensitivity acquisition unit 11 and the noise acquisition unit 12, and executes a preset core algorithm.

[0055] For example, the sound box airflow noise reduction effect evaluation device 10 is arranged in an anechoic chamber. The signal processing unit 13 receives the first sound pressure signal and the second sound pressure signal from the sensitivity acquisition unit 11, and by comparing the two signals, the signal processing unit 13 can determine whether the noise reduction scheme affects the sound pressure sensitivity of the sound box. The calibration target is to adjust the input signal (such as voltage) driving the sound box under test, so that the sound pressure level measured by the sensitivity acquisition unit 11 under the same excitation signal remains consistent before and after noise reduction, thereby ensuring that the subsequent evaluation of airflow noise is conducted under the premise that the overall loudness of the sound box remains unchanged, effectively reducing the evaluation errors caused by changes in sensitivity.

[0056] On the basis of the sensitivity calibration, the signal processing unit 13 processes the first airflow noise time-domain signal and the second airflow noise time-domain signal from the noise acquisition unit 12. Since the airflow noise appears as a chaotic waveform in the time domain and is difficult to quantify directly, the signal processing unit 13 performs frequency domain transformation, such as Fast Fourier Transform (FFT), on the two time-domain signals, respectively, to convert the airflow noise time-domain signal from the time domain to the frequency domain, thereby obtaining the clear noise spectrum before noise reduction and the noise spectrum after noise reduction. Further, according to the noise spectrum before noise reduction and the noise spectrum after noise reduction, the average reduction of the airflow noise sound pressure level in the set frequency range is determined, and a quantitative evaluation result of the noise reduction effect is generated based on the average reduction of the airflow noise sound pressure level. The frequency domain transformation is a signal processing technique used to convert signal analysis from the time domain to the frequency domain to form a frequency spectrum. The average reduction of the airflow noise sound pressure level is a single numerical index representing the comprehensive effect of the noise reduction scheme in the entire airflow noise frequency band, with a unit of decibel (dB). The larger the value, the better the noise reduction effect.

[0057] The sound box air flow noise reduction effect evaluation device provided by the embodiment of the application, through the setting of the independent sensitivity acquisition unit and the noise acquisition unit, and the introduction of the signal processing unit for automatic sensitivity calibration and spectrum analysis, finally outputs the quantitative index of the accurate "air flow noise sound pressure level average reduction amount", effectively overcomes the fuzziness and individual difference of the traditional subjective listening evaluation, changes the qualitative judgment of the noise reduction effect evaluation from the dependence on the human ear experience to the precision measurement of the objective data, significantly improves the reliability, consistency and repeatability of the evaluation results, and thus significantly improves the research and development efficiency of the sound box air flow noise problem troubleshooting and noise reduction scheme optimization.

[0058] In some embodiments, when the signal processing unit is used to determine the air flow noise sound pressure level average reduction amount in the set frequency range, the air flow noise sound pressure level average reduction amount satisfies the following formula:

[0059]

[0060] wherein, refers to the air flow noise sound pressure level average reduction amount; refers to the excitation frequency of the single frequency excitation signal; refers to the highest frequency in the set frequency range; refers to the number of frequency points in the set frequency range; refers to the noise spectrum before noise reduction, refers to the noise spectrum after noise reduction.

[0061] For example, the following process is performed by using a professional electro-acoustic test system: the resonance frequency (f b ) of the measured sound box is determined by applying a sweep signal and measuring the impedance of the measured sound box; the resonance frequency is used as a single frequency excitation signal (f ), which is applied to the measured sound box, and the noise acquisition unit at the outlet of the inverter pipe synchronously acquires the air flow noise time domain signal recorded within 1 to 10 seconds; the acquired air flow noise time domain signal is subjected to fast Fourier transform to convert it into a noise spectrum; through analysis and verification, the main energy of the air flow noise is concentrated in the frequency band of 10 times the resonance frequency (10f b ) to 20 kHz, so the subsequent quantitative evaluation is based on this specific frequency band.

[0062] Correspondingly, the set frequency range is 10f b -20 kHz, and the air flow noise sound pressure level average reduction amount in the frequency range of 10f b -20 kHz is determined by using the above formula. For example Figure 2A schematic diagram of the airflow noise test spectrum provided for the exemplary embodiments of the present application. According to the calculation formula of the average reduction of the airflow noise sound pressure level proposed in the embodiments of the present application, the quantitative results are as follows: the average reduction of the airflow noise sound pressure level of the noise reduction scheme 1 = 6.3 dB, and the average reduction of the airflow noise sound pressure level of the noise reduction scheme 2 = 5.8 dB. Due to , it is objectively determined that the noise reduction effect of the noise reduction scheme 1 is better than that of the scheme 2. This conclusion is highly consistent with the consistent evaluation obtained by a plurality of senior sound tuning experts through subjective blind listening test, thereby powerfully proving that the quantitative indicator of the average reduction of the airflow noise sound pressure level proposed in the embodiments of the present application can accurately and reliably evaluate the performance of the noise reduction scheme, and effectively overcomes the fuzziness and uncertainty of subjective evaluation.

[0063] In some embodiments based on the above embodiments, the sensitivity acquisition unit includes a first microphone, and the first microphone is arranged on an axis of the loudspeaker unit of the measured sound box.

[0064] In some embodiments, the distance between the first microphone and the loudspeaker unit is 1 meter.

[0065] For example, the core component of the sensitivity acquisition unit is the first microphone, which is a sensor capable of converting sound pressure signals into corresponding electrical signals, and its performance needs to meet the requirements of high-precision acoustic measurement. Accordingly, the arrangement of the first microphone follows the following specifications to ensure the accuracy and repeatability of the measurement results: 1) position requirement: the first microphone is arranged on the axis of the loudspeaker unit of the measured sound box, where the "axis" refers to a straight line perpendicular to the loudspeaker diaphragm plane and passing through its geometric center. Placing the microphone on the axis can capture the most direct and undamped sound waves of the loudspeaker, thereby obtaining the most accurate frequency response characteristics; 2) distance requirement: the distance between the first microphone and the loudspeaker unit is set to 1 meter, aiming to balance the consistency of the measurement and the convenience of the actual operation, so that the measured sound pressure level can stably reflect the sensitivity of the loudspeaker.

[0066] Correspondingly, during the test process, the workflow of the sensitivity acquisition unit is as follows: when the measured sound box is excited before and after the implementation of the noise reduction scheme, the first microphone will synchronously acquire the sound waves radiated by the measured sound box and convert them into first and second sound pressure signals. These signals are transmitted to the signal processing unit for subsequent sensitivity calibration, and the core purpose is to ensure that the sound output capability of the sound box remains consistent before and after the noise reduction by adjusting the driving voltage, thereby laying a data foundation for the comparison of the airflow noise.

[0067] The embodiments of the present application reduce the frequency response distortion caused by off-axis measurement by placing the microphone on the axis, thereby obtaining the most real and direct sound output characteristics of the loudspeaker. At the same time, the fixed 1-meter distance provides a unified reference for sensitivity calibration before and after noise reduction, effectively ensuring the fairness and scientific nature of the subsequent airflow noise comparison evaluation, thereby eliminating errors introduced by the randomness of the measurement position.

[0068] In some embodiments, the noise acquisition unit includes a second microphone arranged on the axis of the sound hole of the measured sound box.

[0069] In some embodiments, the distance L between the second microphone and the sound hole satisfies: 0.01 meters ≤ L ≤ 2 meters.

[0070] For example, the core component of the noise acquisition unit is the second microphone, which needs to have high sensitivity and wide frequency band response characteristics to accurately capture the random signal of airflow noise with wide frequency band and low sound pressure level. Accordingly, the arrangement of the second microphone follows the following specifications to ensure the authenticity and effectiveness of the collected signal: 1) Position: the second microphone is arranged on the axis of the sound hole of the measured sound box, where the "axis" refers to a straight line perpendicular to the sound hole plane and passing through its geometric center; 2) Distance requirement: the distance between the second microphone and the sound hole is set to between 0.01 meters and 2 meters.

[0071] In a preferred embodiment, the distance L between the second microphone and the sound hole is 0.5 meters, which is an experienced value that balances the measurement accuracy and operational convenience.

[0072] Correspondingly, during the test process, the workflow of the noise acquisition unit is as follows: when the measured sound box is excited by a single-frequency signal at the resonance frequency point, the air inside and outside the box exchanges at high speed through the sound hole, generating turbulence and noise; the second microphone collects the first airflow noise time domain signal and the second airflow noise time domain signal radiated before and after the implementation of the noise reduction scheme, respectively. These airflow noise time domain signals are the direct data basis for subsequent frequency domain transformation and calculation of the average reduction of airflow noise sound pressure level.

[0073] The embodiments of the present application arrange the second microphone directly opposite the axis of the sound hole and limit its distance to be within the range of 0.01 meters to 2 meters. In addition, the specific distance range can obtain a high signal-to-noise ratio of the noise signal using near-field measurement, ensuring that weak airflow noise can also be effectively captured, and reducing the instability of the sound field or direct airflow impact caused by too close distance, thereby providing a high-quality and reliable original data basis for subsequent spectral analysis and quantitative calculation.

[0074] In the process of airflow noise testing, the second microphone is directly impacted by the high-speed pulse airflow due to being arranged opposite to the sound outlet. The airflow of non-acoustic nature generates a huge pressure fluctuation on the diaphragm of the microphone, which is much larger than the sound pressure signal of the airflow noise to be measured, thereby seriously interfering with or even drowning out the noise data. Therefore, in some embodiments, the second microphone is additionally provided with a wind ball.

[0075] Correspondingly, the wind ball is usually made of porous acoustic foam material, and its working principle is as follows: when the high-speed airflow passes through the complex micropores of the wind ball, its kinetic energy is effectively converted into heat energy and dissipated, so that the airflow speed and pressure are greatly attenuated. This physical barrier can filter out most of the low-frequency, high-pressure fluctuations caused by direct wind impact. While the sound wave is a kind of longitudinal wave with dense and sparse phases, its wavelength is short and can bypass or propagate in the micropore structure, so that the sound pressure level only produces a small, calibratable attenuation. Therefore, the wind ball can effectively suppress wind noise while maximizing the preservation of the acoustic characteristics of the original airflow noise signal.

[0076] In the embodiments of the present application, the wind ball is additionally provided, so that the electrical signal output by the second microphone can more truly reflect the airflow noise spectrum generated at the inverter tube, significantly improving the signal-to-noise ratio and accuracy of subsequent frequency domain transformation and quantitative analysis results, and helping to ensure the reliability of the evaluation results from the data source.

[0077] In some embodiments, the loudspeaker airflow noise reduction effect evaluation device further comprises a first support for supporting the loudspeaker to be measured, a second support for supporting the sensitivity acquisition unit, and a third support for supporting the noise acquisition unit.

[0078] The first support is used to stably support the loudspeaker to be measured, and its role is to ensure that the loudspeaker to be measured, especially its sound outlet and loudspeaker unit, maintain absolute fixation of the spatial position during the test, reduce the relative geometric relationship between the loudspeaker to be measured and the microphone due to accidental movement or vibration, and thus reduce the measurement error. The second support is used to support and fix the sensitivity acquisition unit (the first microphone), and the support needs to be adjustable to accurately position the first microphone at a distance of 1 meter from the axis of the loudspeaker unit. The third support is used to support and fix the noise acquisition unit (the second microphone), and also needs to be accurately adjusted to ensure that the second microphone is stably arranged at a predetermined distance (such as 0.5 meters) from the axis of the sound outlet and directly opposite the sound outlet.

[0079] In the embodiments of the present application, the position uncertainty, vibration and personnel safety risk caused by handheld measurement or simple placement are minimized by physical isolation, thereby providing a basic guarantee for the reliability and repeatability of the entire quantitative evaluation process from the hardware level.

[0080] Exemplarily, Figure 3 A layout schematic diagram of the sound box air flow noise reduction effect evaluation device with the inverter tube facing forward is provided for the exemplary embodiments of the present application, Figure 4 A layout schematic diagram of the sound box air flow noise reduction effect evaluation device with the inverter tube facing backward is provided for the exemplary embodiments of the present application, Figure 5 A layout schematic diagram of the sound box air flow noise reduction effect evaluation device with the inverter tube facing left / right is provided for the exemplary embodiments of the present application, Figure 6 A layout schematic diagram of the sound box air flow noise reduction effect evaluation device with the inverter tube facing downward is provided for the exemplary embodiments of the present application. As Figure 3 , Figure 4 , Figure 5 and Figure 6 shown, for the sound box with the inverter tube facing forward, backward, left / right, the noise collection unit 12 is arranged directly in front of the inverter tube (i.e. the sound outlet hole) for collecting the air flow noise signals radiated by the sound outlet hole 143 of the sound box 14 before and after the noise reduction; in order to reduce the influence of wind on the air flow noise test results, the noise collection unit 12 is usually equipped with a windproof ball 15; the distance L1 between the sound outlet hole 143 of the inverter tube and the noise collection unit 12 is between 0.01m and 2m, and L1 is usually 0.5m; for the sound box 14 with the inverter tube facing downward, the noise collection unit 12 needs to be arranged directly in front of the bottom sound outlet hole 143 of the sound box 14 for monitoring the air flow noise signals generated by the sound box 14, the distance L1 between the bottom sound outlet hole 143 of the sound box 14 and the noise collection unit 12 is between 0.01m and 2m, and L1 is usually 0.5m; a sensitivity collection unit 11 also needs to be arranged directly in front of the loudspeaker unit 142 for testing the sensitivity of the sound box 14, and the distance L2 between the loudspeaker unit 142 and the sensitivity collection unit 11 is 1m. The sound box 14, the sensitivity collection unit 11 and the noise collection unit 12 are respectively supported by a first support 16, a second support 17 and a third support 18. Among them, the first support 16 is for example a sound box support, and the second support 17 and the third support 18 are respectively microphone supports.

[0081] The above embodiments introduce the implementation mode of the sound box air flow noise reduction effect evaluation device, and next, the application of the sound box air flow noise reduction effect evaluation device is introduced through specific embodiments.

[0082] Figure 7 A flowchart of the sound box air flow noise reduction effect evaluation method is provided for the exemplary embodiments of the present application. The sound box air flow noise reduction effect evaluation method provided by the embodiments of the present application is applied to the signal processing unit in any one of the above embodiments. As Figure 7 shown, the sound box air flow noise reduction effect evaluation method comprises:

[0083] S701, obtaining a first sound pressure signal and a second sound pressure signal respectively radiated by the measured sound box before and after noise reduction.

[0084] S702, sensitivity calibration is performed on the measured sound box according to the first sound pressure signal and the second sound pressure signal, so as to ensure that the sensitivities of the measured sound box before and after noise reduction are consistent.

[0085] S703, obtaining a first air flow noise time domain signal and a second air flow noise time domain signal respectively radiated by the sound hole of the measured sound box before and after noise reduction.

[0086] S704, frequency domain transformation is performed on the first air flow noise time domain signal and the second air flow noise time domain signal, to obtain a noise spectrum before noise reduction and a noise spectrum after noise reduction, and to determine an average air flow noise sound pressure level reduction in a set frequency range according to the noise spectrum before noise reduction and the noise spectrum after noise reduction, and to generate a quantitative evaluation result of the noise reduction effect based on the average air flow noise sound pressure level reduction.

[0087] Wherein, the average air flow noise sound pressure level reduction satisfies the following formula:

[0088]

[0089] Wherein, is the average air flow noise sound pressure level reduction; is the excitation frequency of the single frequency excitation signal; is the highest frequency in the set frequency range; is the number of frequency points in the set frequency range; is the noise spectrum before noise reduction, is the noise spectrum after noise reduction.

[0090] For example, a Bluetooth sound box is applied with noise reduction scheme 1 and noise reduction scheme 2 respectively for evaluation. For example Figure 2 The schematic diagram of the air flow noise test spectrum provided by the example embodiment of the application. According to the calculation formula of the average air flow noise sound pressure level reduction proposed in the embodiment of the application, the quantitative result is as follows: the average air flow noise sound pressure level reduction of the noise reduction scheme 1 = 6.3dB, and the average air flow noise sound pressure level reduction of the noise reduction scheme 2 = 5.8dB; since , it can be objectively determined that the noise reduction effect of the noise reduction scheme 1 is better than that of the scheme 2; further, the signal processing unit outputs a structured quantitative evaluation report, which presents the specific numerical value of the average air flow noise sound pressure level reduction of the noise reduction scheme 1 and the scheme 2, the comparison result between them, and finally gives the clear effect of the conclusion of the advantage and disadvantage.

[0091] It should be noted that the sound box air flow noise reduction effect evaluation device and method described in the embodiments of the present application are based on the quantification evaluation principle and device architecture. Therefore, for those skilled in the art, it can be understood that the present scheme does not make specific restrictions on the type (such as inverse phase tube sound box, acoustic labyrinth sound box, acoustic super material sound box and band-pass sound box), shape and number and type of loudspeakers of the measured sound box. Whether it is a traditional box-type sound box, a portable Bluetooth sound box, a smart sound box, or a single, multiple loudspeaker units of different sizes or materials, or any low-frequency enhancement structure such as inverse phase tube, acoustic labyrinth, acoustic super material or band-pass design, the present scheme is applicable.

[0092] In summary, the present application has at least the following advantages:

[0093] I. By setting up independent sensitivity acquisition unit and noise acquisition unit, and introducing signal processing unit for automatic sensitivity calibration and frequency spectrum analysis, finally outputting the quantitative index of "air flow noise sound pressure level average reduction", effectively overcoming the fuzziness and individual difference of traditional subjective listening evaluation, changing the qualitative judgment of noise reduction effect depending on human ear experience to precise measurement depending on objective data, significantly improving the reliability, consistency and repeatability of the evaluation results, thereby significantly improving the research and development efficiency of sound box air flow noise problem troubleshooting and noise reduction scheme optimization.

[0094] II. By arranging the second microphone directly opposite the sound hole axis and limiting its distance within the range of 0.01 meters to 2 meters, it is ensured that the microphone can be directly aimed at the core area where the air flow noise is generated and radiated, which helps to capture the highest signal intensity and purest noise source information. In addition, the specific distance range can obtain high signal-to-noise ratio noise signals using near-field measurement, ensuring that weak air flow noise can also be effectively captured, and reducing the instability of the sound field or the direct impact of the air flow caused by too close distance, thereby providing a high-quality and reliable raw data basis for subsequent frequency spectrum analysis and quantitative calculation.

[0095] III. By adding a windproof ball, the electrical signal output by the second microphone can more truly reflect the air flow noise spectrum generated at the inverse phase tube, significantly improving the signal-to-noise ratio and accuracy of the subsequent frequency domain transformation and quantitative analysis results, and helping to ensure the reliability of the evaluation results from the data source.

[0096] Figure 8 The structure diagram of the signal processing unit provided for the exemplary embodiments of the present application is shown in FIG. 13. As shown in FIG. 13, the signal processing unit 13 of the present embodiment includes: Figure 8

[0097] at least one processor 131; and a memory 132 in communication connection with the at least one processor; ​

[0098] The memory 132 stores instructions executable by the at least one processor 131, and the instructions are executed by the at least one processor 131 to enable the signal processing unit to perform the method of any of the preceding embodiments.

[0099] Optionally, the memory 132 can be independent or integrated with the processor 131.

[0100] The memory 132 can include a high-speed Random Access Memory (RAM) and can also include a non-volatile memory such as at least one disk memory.

[0101] The processor 131 can be a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application. Specifically, when implementing the sound box airflow noise reduction effect evaluation method described in the foregoing method embodiments, the signal processing unit can be, for example, a server or other electronic device with processing function.

[0102] Optionally, the signal processing unit can further include a communication interface 133. In a specific implementation, if the communication interface 133, the memory 132 and the processor 131 are implemented independently, the communication interface 133, the memory 132 and the processor 131 can be connected to each other through a bus and complete communication among them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc., but it does not mean that there is only one bus or only one type of bus.

[0103] Optionally, in a specific implementation, if the communication interface 133, the memory 132 and the processor 131 are integrated on a chip, the communication interface 133, the memory 132 and the processor 131 can complete communication through an internal interface.

[0104] The implementation principle and technical effects of the signal processing unit provided in the embodiments can be referred to the foregoing embodiments, which will not be described here.

[0105] The embodiment of the present application further provides a computer readable storage medium, and the computer readable storage medium stores computer execution instructions. When the computer execution instructions are executed, the computer execution instructions are used for implementing the method steps in the method embodiments, and the specific implementation manners and technical effects are similar, and details are not described herein.

[0106] The computer readable storage medium described above can be implemented by any type of volatile or nonvolatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special purpose computer.

[0107] An exemplary readable storage medium is coupled to the processor, so that the processor can read information from the readable storage medium, and can write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in a special integrated circuit. Of course, the processor and the readable storage medium can also exist as discrete components in the sound box air flow noise reduction effect evaluation device.

[0108] The embodiment of the present application further provides a computer program product, including a computer program. When the computer program is executed, the method steps in the method embodiments are implemented, and the specific implementation manners and technical effects are similar, and details are not described herein.

[0109] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments. The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0110] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0111] It is to be understood that the application is not limited to the precise construction herein described and as shown in the attached drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is to be indicated by the appended claims, rather than the description and examples.

Claims

1. A device for evaluating the noise reduction effect of sound box airflow noise, characterized in that, The sound box air flow noise reduction effect evaluation device comprises a sensitivity acquisition unit, a noise acquisition unit and a signal processing unit, wherein: The sensitivity acquisition unit is used for acquiring first and second sound pressure signals respectively radiated by the measured sound box before and after noise reduction; The signal processing unit is electrically connected with the noise acquisition unit and the sensitivity acquisition unit, and is used for performing sensitivity calibration on the measured sound box according to the first and second sound pressure signals, so as to ensure that the sensitivities of the measured sound box before and after noise reduction are consistent; The noise acquisition unit is used for acquiring first and second air flow noise time domain signals respectively radiated by the sound hole of the measured sound box before and after noise reduction; The signal processing unit is also used for performing frequency domain transformation on the first and second air flow noise time domain signals to obtain noise frequency spectrums before and after noise reduction, and determining an average air flow noise sound pressure level reduction in a set frequency range according to the noise frequency spectrums before and after noise reduction, and generating a quantitative evaluation result of noise reduction effect based on the average air flow noise sound pressure level reduction.

2. The loudspeaker airflow noise reduction effect evaluation device according to claim 1, characterized in that, When the signal processing unit is used for determining the average air flow noise sound pressure level reduction in the set frequency range, the average air flow noise sound pressure level reduction satisfies the following formula: wherein, refers to the average reduction of the sound pressure level of the airflow noise; refers to the excitation frequency of the single-frequency excitation signal; refers to the highest frequency within the set frequency range; refers to the number of frequency points within the set frequency range; refers to the noise spectrum before the noise reduction, refers to the noise spectrum after the noise reduction.

3. The loudspeaker airflow noise reduction effect evaluation device according to claim 1 or 2, characterized in that, The sensitivity acquisition unit comprises a first microphone, which is arranged on the axis of the loudspeaker unit of the measured sound box.

4. The loudspeaker airflow noise reduction effect evaluation device according to claim 3, characterized in that, The distance between the first microphone and the loudspeaker unit is 1 meter.

5. The loudspeaker airflow noise reduction effect evaluation device according to claim 1 or 2, characterized in that, The noise acquisition unit comprises a second microphone, which is arranged on the axis of the sound hole of the measured sound box.

6. The loudspeaker airflow noise reduction effect evaluation device according to claim 5, characterized in that, The distance L between the second microphone and the sound hole satisfies: 0.01 meters≤L≤2 meters.

7. The loudspeaker airflow noise reduction effect evaluation device according to claim 6, characterized in that, The distance L between the second microphone and the sound hole is 0.5 meters.

8. The loudspeaker airflow noise reduction effect evaluation device according to claim 5, characterized in that, The second microphone is additionally provided with a windproof ball.

9. The loudspeaker airflow noise reduction effect evaluation device according to claim 1 or 2, characterized in that, The device further comprises a first support for supporting the measured sound box, a second support for supporting the sensitivity acquisition unit and a third support for supporting the noise acquisition unit.

10. A method for evaluating the noise reduction effect of sound box airflow noise, characterized in that, The signal processing unit applied to the sound box air flow noise reduction effect evaluation device of any one of claims 1 to 9, the sound box air flow noise reduction effect evaluation method comprises: Acquiring first and second sound pressure signals respectively radiated by the measured sound box before and after noise reduction; According to the first and second sound pressure signals, the sensitivity of the measured sound box is calibrated to ensure that the sensitivities of the measured sound box before and after noise reduction are consistent; Acquiring first and second air flow noise time domain signals respectively radiated by the sound hole of the measured sound box before and after noise reduction; The signal processing unit is also used for performing frequency domain transformation on the first and second air flow noise time domain signals to obtain noise frequency spectrums before and after noise reduction, and determining an average air flow noise sound pressure level reduction in a set frequency range according to the noise frequency spectrums before and after noise reduction, and generating a quantitative evaluation result of noise reduction effect based on the average air flow noise sound pressure level reduction. The first airflow noise time domain signal and the second airflow noise time domain signal are subjected to frequency domain transformation to obtain a noise spectrum before noise reduction and a noise spectrum after noise reduction, and an average reduction amount of an airflow noise sound pressure level in a set frequency range is determined according to the noise spectrum before noise reduction and the noise spectrum after noise reduction, and a quantitative evaluation result of a noise reduction effect is generated based on the average reduction amount of the airflow noise sound pressure level.

Images