A method for quantitatively evaluating the directivity of a wind noise source

Abstract

The application particularly relates to a wind noise source directivity quantization evaluation method. The method comprises the following steps: S1, wind noise directivity test of an in-vehicle spherical array, arranging a spherical microphone array to obtain a spatial distribution nephogram of the in-vehicle wind noise source; S2, spatial angle partition of the wind noise directivity, decomposing the noise source according to spatial regions, and performing equi-angle partition on the in-vehicle space; S3, frequency decomposition of the wind noise directivity, constructing an information matrix according to different frequencies; S4, establishing a quantization evaluation index of space and frequency according to the sound source information matrix, and identifying a short board; and S5, combining the in-vehicle spherical array test position and the quantization evaluation index to form an evaluation method classified according to working conditions, and judging the wind noise source directivity level of a developed vehicle model. The spatial angle partition and frequency decomposition of the sound source effectively support the achievement of the whole vehicle wind noise performance target and the analysis of the wind noise problem.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of automobile performance evaluation, and particularly relates to a wind noise source directivity quantification evaluation method. BACKGROUND

[0002] Wind noise is air-borne noise, including turbulent flow noise, surface pressure fluctuation noise, boundary layer flow whistle, cavity noise, leakage noise, wind-induced vibration noise and other noise components. Automobile wind noise refers to the noise generated by the interaction of air and vehicle body during driving.

[0003] Chinese invention patent CN112881019A "A method for measuring engine noise directivity in a conventional indoor experimental environment" discloses a method for measuring engine noise directivity in a conventional indoor experimental environment, which solves the problem that the influence and damage of the engine noise radiation field caused by wall reflection and other reasons in a conventional indoor environment, making it difficult to conduct noise experiments on the engine. Through a large number of experimental researches on the noise characteristics of aero-engines and their components in a conventional indoor laboratory, the noise experimental capability of aero-engines will be greatly improved. And according to the microphone array experimental measurement method and the directivity measurement method based on sub-array, the directivity characteristics of the engine can be accurately measured in a conventional indoor environment.

[0004] This patent focuses on the measurement of engine directivity characteristics in a conventional indoor environment, locks the engine inlet noise source position, and focuses on the test method of directivity noise. It does not establish a noise source directivity noise decomposition and quantification evaluation method, and different vehicle noise directivities cannot be compared horizontally. SUMMARY

[0005] Based on the above background, the present application provides a wind noise source directivity quantification evaluation method, which is based on spatial angle partitioning and frequency decomposition of sound sources, and effectively supports the achievement of vehicle wind noise performance targets and the analysis of wind noise problems.

[0006] The method comprises the following steps:

[0007] S1, wind noise directivity test of in-vehicle spherical array, arranging a spherical microphone array to obtain a spatial distribution cloud diagram of in-vehicle wind noise sources;

[0008] S2, wind noise directivity spatial angle partitioning, decomposing noise sources according to spatial regions, and equally partitioning the in-vehicle space according to angles;

[0009] S3, wind noise directivity frequency decomposition, constructing an information matrix according to different frequencies;

[0010] S4, establishing a quantification evaluation index of space and frequency according to the sound source information matrix, and identifying the short board;

[0011] S5, combine the in-vehicle spherical array test position and the quantitative evaluation index, form the evaluation method classified according to the working condition, judge the development vehicle wind noise source directivity level.

[0012] Further, the test is carried out in an acoustic special wind tunnel laboratory, excluding external environmental temperature, wind direction and wind speed interference.

[0013] Further, the center of the spherical microphone array is arranged on the Z-direction section and is located at the X-direction center and the Y-direction center;The identification result is a noise source distribution cloud picture on a three-dimensional model, and the noise source amplitude is distinguished by color.

[0014] Further, the Z-direction section is the transverse section of the passenger's ear in the height direction of the automobile, the X-direction is the front-rear direction of the automobile, and the Y-direction is the left-right direction of the automobile.

[0015] Further, in step S2, the spherical microphone array is taken as the center for division when the in-vehicle space is equally angularly divided.

[0016] Further, the information matrix in step S3 includes the spatial angle, the noise frequency and the sound source amplitude.

[0017] Further, in step S4, the sound source amplitude corresponding to each spatial angle is subtracted from the average sound source of each position of the spatial angle, and each angle of 360° corresponds to a difference value from the average value.

[0018] Further, if the difference value is ≤0, the result is 0, and if the difference value is >0, the result is the difference value.

[0019] Further, according to the information matrix containing the spatial angle, the noise frequency and the sound source difference value, a radar chart is drawn, the text information is converted into image information, and the limit value of the difference value is marked.

[0020] The beneficial effects of the present application are that the present application establishes a wind noise source directivity quantitative evaluation method based on in-vehicle spherical array spatial angle zoning and frequency decomposition, proposes a directivity noise quantitative evaluation method for sound sources according to spatial angle zoning and frequency decomposition, and effectively supports the achievement of vehicle wind noise performance targets and the analysis of wind noise problems. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a schematic diagram of the spherical array microphone;

[0022] Figure 2 It is a spherical array microphone arrangement position diagram;

[0023] Figure 3 Fig. 2 is a schematic diagram of a wind noise directivity angle partition for a wind noise directivity diagram;

[0024] Figure 4 Fig. 4 is a radar diagram drawn according to an information matrix;

[0025] Figure 5 Fig. 5 is a schematic diagram of a wind noise directivity level DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0029] The wind noise source directivity quantification evaluation method provided by the present embodiment will be introduced below:

[0030] Step S1: Wind noise directivity test of in-vehicle spherical array

[0031] The microphone array is formed by arranging a group of microphones in different positions in space in a certain way, and the spatial position of the sound source is obtained by using the spatial information of the signals collected by the microphones. For example, Figure 1As shown, the in-vehicle spherical array belongs to a kind of microphone array, and is a beamforming sound source identification method of a spherical microphone array, which is used to identify in-vehicle noise sources, is suitable for steady-state and transient sound source identification, and the analysis result is a noise source distribution cloud diagram on a three-dimensional model, and the noise source amplitude is distinguished by color.

[0032] In order to facilitate the quantitative comparison of the wind noise directivity of different vehicles below, the arrangement position of the spherical array needs to be specified: the center of the spherical microphone array is arranged on the Z-section and is located at the center of the X-section and the center of the Y-section. As shown in Figure 1 As shown, the Z-section is the Z-section of the passenger's ear (the height direction of the automobile), the X-section (the front-rear direction of the automobile) is the center position of the Z-section and the front-rear windshield section line, and the Y-section (the left-right direction of the automobile) is the middle section of the automobile in the longitudinal direction.

[0033] Excluding external environmental temperature, wind direction, wind speed and other interference, the test is carried out in an acoustic special wind tunnel test room. The test conditions include wind speed and yaw angle. Taking the condition of a certain vehicle model at a speed of 120 km / h and a yaw angle of 0° as an example, since the amplitude of each position in the spatial distribution cloud diagram of the in-vehicle wind noise source is greatly different, the cloud diagram can only lock the noise source in the rear windshield area as being too large, but cannot know how much larger the noise source amplitude in this area is compared with that in other areas, and can only be qualitatively analyzed, and cannot be quantitatively compared with other vehicle models or competitive products.

[0034] Step S2: Spatial angle partitioning of wind noise directivity

[0035] Decompose the noise source according to the spatial region, and partition the in-vehicle space at equal angles. The more the number of partitions, the more accurate the subsequent comparison of the sound source according to the angle, but the longer the partition operation time becomes with the increase of the number of partitions. Taking the example of 16 equal divisions of the spatial angle, the angle interval is 22.5°, as shown in Figure 3 As shown, different positions of the passenger correspond to different angle partitions, such as the driver's ear which is mainly affected by three spatial angle zones of 292.5°, 315° and 337.5°.

[0036] Step S3: Frequency decomposition of wind noise directivity

[0037] In addition to obtaining the spatial information of the wind noise source, the time characteristics also need to be analyzed to more comprehensively analyze the noise source. The analysis frequency range of the spherical array is different due to factors such as array size and microphone spacing. Taking the spherical array with an analysis frequency range of 500 Hz-8000 Hz as an example, the frequency is decomposed according to the 1 / 3 octave most suitable for human ear perception, the sound source amplitude with spatial position information at each frequency is obtained, and an information matrix containing spatial angle, frequency and sound source amplitude is formed, as shown in Table 1.

[0038] Table 1:

[0039]

[0040] Step S4: Wind noise directivity quantification evaluation index

[0041] According to the sound source information matrix, a quantification evaluation index of space and frequency is established to identify the short board. Taking 1 / 3 octave frequency and 16 equal angle as an example, the difference between the sound source amplitude of each angle and the average sound source of each position is calculated. If the difference is ≤0, the result is 0; if the difference is >0, the result is the difference. Each angle of 360° corresponds to a difference from the average, and the larger the difference, the greater the contribution to the noise source, which is the key area for subsequent engineering program improvement. Similarly, at other frequencies, each angle corresponds to a difference from the average sound source of the frequency, forming an information matrix containing angle, noise frequency and sound source difference (difference between sound source amplitude and average), as shown in Table 2.

[0042] Table 2:

[0043]

[0044] To more intuitively display the short board of each angle and each frequency sound source, a radar chart is drawn according to the information matrix, as shown in Figure 4 . Taking a certain vehicle as an example, the shortest sound source is located at 180° and 157.5° (corresponding to the rear windshield area) of 800Hz 1 / 3 octave, with a difference of 4.5dB between the sound source amplitude and the average, providing a direction for subsequent wind noise problem analysis and program verification.

[0045] Step S5: Wind noise directivity evaluation index classification

[0046] Based on the above-mentioned in-vehicle spherical array test position, wind noise directivity quantification evaluation index, the wind noise directivity data of the benchmark vehicle or each level vehicle can be compared and summarized to form an evaluation method classified by working conditions, to judge the wind noise source directivity level of the developed vehicle, and to provide an evaluation basis for wind noise directivity control.

[0047] For example, for the working condition of vehicle speed 120km / h and yaw angle 0°, a 4-level evaluation index of wind noise directivity is established, L4 level range: <2.0dB, L3 level range: 2.0-3dB, L2 level range: 3dB-4dB, L1 level range: >4dB, forming a wind noise directivity classification evaluation, and quantitatively analyzing the directivity level of different vehicles, as shown in Figure 5 .

Claims

1. A method for quantitatively evaluating the directivity of wind noise sources, characterized in that, The method includes the following steps: S1. In-vehicle spherical array wind noise directivity test: Arrange a spherical microphone array to obtain a spatial distribution cloud map of in-vehicle wind noise sources; S2. Wind noise directional spatial angle zoning: Decompose noise sources according to spatial regions and perform equal-angle zoning for the vehicle interior space; S3. Wind noise directivity frequency decomposition, constructing an information matrix based on different frequencies; the information matrix includes spatial angle, noise frequency, and sound source amplitude. S4. Based on the sound source information matrix, establish quantitative evaluation indicators for space and frequency to identify shortcomings; calculate the difference between the corresponding sound source amplitude at each spatial angle and the average sound source value at each position within that spatial angle. Each angle in the 360° space corresponds to a difference from the average value, and at each frequency, each spatial angle corresponds to a difference from the average sound source value at that frequency, forming an information matrix containing spatial angle, noise frequency, and sound source difference; if the difference is ≤0, the result is 0; if the difference is >0, the result is the difference value; draw a radar chart based on the information matrix containing spatial angle, noise frequency, and sound source difference, converting text information into image information, and marking the limits of the difference; S5. Combining the in-vehicle spherical array test location and quantitative evaluation indicators, an evaluation method based on operating conditions is formed to determine the wind noise source directivity level of the developed vehicle model.

2. The quantitative evaluation method according to claim 1, characterized in that, The tests were conducted in a dedicated acoustic wind tunnel laboratory to eliminate interference from external environmental factors such as temperature, wind direction, and wind speed.

3. The quantitative evaluation method according to claim 1, characterized in that, The spherical microphone array is centrally located on the Z-axis section and at the center of both the X and Y axes; the identification result is a noise source distribution cloud map on a three-dimensional model, with the noise source amplitude distinguished by color.

4. The quantitative evaluation method according to claim 3, characterized in that, The Z-direction section is the transverse section where the occupant's ear is located in the height direction of the vehicle, the X-direction is the front-to-back direction of the vehicle, and the Y-direction is the left-to-right direction of the vehicle.

5. The quantitative evaluation method according to claim 1, characterized in that, In step S2, when dividing the interior space into equal-angle sections, the division is centered on the spherical microphone array.

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