CN114061966A - Evaluation method and evaluation system for vehicle abnormal sound performance - Google Patents
Evaluation method and evaluation system for vehicle abnormal sound performance Download PDFInfo
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Abstract
The invention relates to an evaluation method for vehicle abnormal sound performance, which comprises the following steps: detecting a sound inside the vehicle using a microphone disposed inside the vehicle under the test condition; processing a signal output from the microphone by a signal processing unit: transforming the signal into a frequency domain to obtain a time-varying frequency spectrum, and calculating the variation of the sound pressure of each point in the time-varying frequency spectrum relative to the adjacent time interval and the adjacent frequency interval; and evaluating abnormal sound based on the variation. The present invention also relates to a computer-readable medium and an evaluation system for vehicle abnormal sound performance, which includes: a microphone; a signal processing unit: the transformation module is used for transforming the signal into a frequency domain to obtain a time-varying frequency spectrum; the calculation module is used for calculating the variation of the sound pressure of each point in the time-varying frequency spectrum relative to the adjacent time interval and the adjacent frequency interval; and the evaluation module is used for evaluating the abnormal sound performance of the vehicle based on the variation.
Description
Technical Field
The present invention relates to an evaluation method for vehicle abnormal sound performance, a computer-readable medium, and an evaluation system for vehicle abnormal sound performance.
Background
Along with the increase of the mileage of the vehicle, the road using condition and the working condition, the parts are inevitably loosened. When a vehicle runs on a rough road surface, a vehicle chassis is excited due to the unevenness of the road surface, causing friction and collision between various interior components of the vehicle and emitting abnormal noise. The abnormal sound performance of the vehicle is extremely easy to be perceived by a vehicle user, and the riding comfort of passengers is influenced. At present, the abnormal sound is identified and judged mainly by adopting a subjective evaluation method, which is easily restricted by factors such as human emotion, ambient environment and the like and cannot ensure the repeatability of an evaluation result; on the other hand, a lot of time is consumed to complete subjective evaluation under various vehicle speeds on all roads, which causes personnel and time consumption. Therefore, there is a need for an objective evaluation method and an evaluation system for vehicle abnormal sound performance, in which objective parameters are used to represent the abnormal sound performance of a vehicle.
Disclosure of Invention
The invention aims to provide an evaluation method for vehicle abnormal sound performance, a computer readable medium and an evaluation system for vehicle abnormal sound performance. According to the technical scheme of the invention, the objective evaluation on the abnormal sound performance of the vehicle can be realized.
A first aspect of the invention relates to a method for evaluating the abnormal-sound performance of a vehicle, the method including the steps of:
-detecting sounds inside the vehicle under test conditions using a microphone arranged inside the vehicle;
-processing the signal output from the microphone by a signal processing unit comprising:
-transforming the signal into the frequency domain to obtain a time-varying spectrum of the preprocessed signal; and is
-calculating the amount of change of the sound pressure of each point in the time-varying spectrum with respect to its neighboring time interval and neighboring frequency interval,
-evaluating the abnormal-sound performance of the vehicle based on the variation amount.
Vehicle abnormal noise generally occurs in the positions of vehicle components such as a door trim, a center console, a center armrest, an a pillar, and a B pillar in the vehicle interior. In order to be able to test the vehicle for abnormal noise, the vehicle is driven under test conditions. In the test condition, the driving surface provides an excitation to the vehicle chassis, under the effect of which there may be friction or collisions between various components of the vehicle, thus emitting an abnormal sound.
In order to evaluate the vehicle abnormal noise performance, particularly, the abnormal noise at the position of the above-described vehicle component, the sound inside the vehicle is detected using a microphone provided inside the vehicle under the test condition. Then, processing a signal output from the microphone by a signal processing unit, the signal processing including: transforming the signal into the frequency domain to obtain a time-varying frequency spectrum of the preprocessed signal. It has been found that the human ear is more sensitive to tonal characteristics (i.e. frequency characteristics) and to rhythmic characteristics (i.e. time characteristics) than to absolute loudness, sharpness or roughness, so that the response of the auditory system of the human ear to noise can be examined by the time-varying spectrum of the sound signal in the time and frequency domains.
In the present invention, the signal processing further includes: the variation of sound pressure of each point in the time-varying frequency spectrum with respect to the adjacent time interval and the adjacent frequency interval is calculated. Further, the abnormal sound performance of the vehicle is evaluated based on the amount of change. The vehicle abnormal sound performance is evaluated with respect to the auditory characteristics of the human ear by using the relative change of each point in the time-varying frequency spectrum in a small neighborhood. This means that if the sound pressure in the time-varying spectrum varies strongly over a short temporal neighborhood and/or over a small frequency neighborhood, the detected sound is often evaluated as annoying noise.
The invention is based on the idea that the human ear is not usually sensitive to a generally steady-state signal or to a slowly varying sound signal. In order to discern the change in the sound signal, the auditory system of the human ear typically automatically establishes a reference signal based on the just-heard sound and determines the heard sound signal based on the reference signal. Thus, sudden changes in sound are more easily assessed as disturbing or obstructive. In order to simulate the acoustic properties of the human ear, the variation in the smaller time and frequency domains is calculated in the evaluation method according to the invention and the vehicle abnormal sound performance is evaluated accordingly. Vehicle abnormal noise is caused by instability of sound signals generated by mutual friction or collision between vehicle parts, and human ears are sensitive to such unstable signals. Therefore, compared with the prior art that the relative values of acoustic parameters (such as loudness, sharpness, roughness and the like) are directly adopted to evaluate the abnormal sound performance of the vehicle, the method for evaluating the abnormal sound performance of the vehicle by calculating the relative variation of the sound signals can be closer to the auditory effect of human ears, so that a more accurate and practical evaluation effect is obtained. In addition, the method can objectively evaluate the abnormal sound of the vehicle, reduces the interference of human factors in subjective evaluation on the evaluation result, reduces the personnel and time consumption and improves the repeatability of the evaluation result. The method can be applied to the abnormal sound performance evaluation of various vehicle types.
According to one embodiment of the present invention, calculating the variation of the sound pressure of each point in the time-varying frequency spectrum with respect to its adjacent time interval and/or adjacent frequency interval comprises: for each point in the time-varying spectrum, an average of the sound pressures within a time interval adjacent to the current time of the point (in particular a time interval preceding the current time, e.g. a time interval of 1ms, 2ms, 5ms, 10ms, 50ms, 100ms, 200 ms) and an average of the sound pressures within a frequency interval adjacent to the current frequency of the point (e.g. 4, 8, 10 sample points or 1 bark, 2 bark, 5 bark, 1Mel, 2Mel, 5Mel, etc.) are determined, respectively, and the variation is calculated by integrating the difference of the sound pressure of the point and these average values, or, for each point in the time-varying spectrum, an average of the sound pressures within the time-frequency region adjacent to the point (e.g., 1 bark by 50ms, 2Mel by 200ms, etc.) is determined, and the variation is calculated by taking the difference between the sound pressure at the point and the average. Here, the average value of the sound pressures within a set time interval before the current sound pressure, the average value of the sound pressures within the frequency interval adjacent to the current frequency, and/or the average value of the sound pressures within a time-frequency region adjacent to the current point are used as reference values of the sound pressures, and the relative change of the sound pressures can be obtained by calculating a difference between an actual value of the current sound pressure and the reference values. In particular, if the amount of change exceeds a predetermined threshold, it is determined that the detected sound is sufficient to be determined as noise by a person, and therefore it is determined that the vehicle abnormal sound performance is poor. Here, the maximum value, the average value, the root mean square, and the like of the difference value over the entire time-varying spectrum may be taken into consideration to evaluate the abnormal sound performance of the vehicle, and in particular, the maximum value, the average value, and the root mean square may be compared with a preset threshold value.
According to one embodiment of the invention, the difference between the sound pressure at the point and the average value of the sound pressures in the adjacent time intervals is integrated by weighting the difference between the sound pressure at the point and the average value of the sound pressures in the adjacent frequency intervals. The different degree of contribution of the temporal and frequency characteristics to the noise estimate is set by a weighting calculation. For example, weighting coefficients for the variations in the time domain and the frequency domain are set, respectively, resulting in weighted variations. The weighted total or average thus obtained is more able to simultaneously take into account the different degrees of response of the human ear to time or frequency variations.
Signals within a predetermined time period (e.g., 10s) may be intercepted for processing in the present invention. Thereby, the amount of data to be processed by the signal processing unit is reduced, thereby improving processing efficiency. Preferably, a plurality of sets of signals within the predetermined time period may be intercepted so as to average the evaluation results, thereby improving the accuracy of the evaluation method. In the signal processing unit, the detected signal may be slid by a preset time window. The time window may be a rectangular window, a Hanning window (Hanning), a Hamming window (Hamming), or the like. Whereby the signals are intercepted into sets of signals having a length corresponding to the length of the time window.
According to one embodiment of the invention, the signal is transformed into the frequency domain by a fast fourier transform or an auditory model. In the auditory model, for example, the transfer function and the physiological and psychological effects of the human ear response can be applied. First, the sound signal is pre-processed using the external to internal ear transfer function. Considering next the frequency division effect of the cochlea, the outer end of the cochlea is sensitive to high frequencies and the inner end of the cochlea is sensitive to low frequencies, and such characteristics can be simulated by a group of band-pass filters with different center frequencies. The acoustic vibrations then propagate along the basilar membrane and generate electrical currents within the auditory nerve fibers. Since the nerve fibers limit the electrical signal below the maximum frequency when passing it, low pass filters are used to simplify the model. The auditory model can be established based on the physiological structure of the human ear, and psychoacoustic factors are fully considered, so that the auditory system of the human ear can be well simulated.
According to one embodiment of the invention, the signals are preprocessed, in particular filtered out to within 500Hz, by means of weighting networks and/or filters before they are transformed into the frequency domain. Since the human ear has different sensitivities to different sound frequencies, weighting networks in the form of filters, such as a, B, C weighting networks, can be used to simulate the auditory response of the human ear. The signals to be processed are modified by means of the selected weighting network, so that the conformity and the accuracy of the evaluation method to the auditory sensation of the human ear are improved. Furthermore, the signals are preferably preprocessed by means of filters, in particular signals within 500Hz are filtered out. When a vehicle runs under a test condition, a microphone provided in the vehicle interior not only collects vehicle abnormal noise in the vehicle interior, but also may collect interference noise such as chassis noise, road noise, tire noise, and the like of the vehicle. By setting a lower limit of 500Hz, these interference noises can be filtered out, thereby improving the accuracy of the evaluation method. Preferably, before the vehicle abnormal sound test is carried out, the tire pressure of the vehicle is ensured to meet the tire pressure requirement specified by a manufacturer, so as to prevent the influence of the tire pressure noise on the evaluation result. More preferably, only signals of 500Hz to 10000Hz are retained by the band pass filter, further simplifying the signal processing.
According to one embodiment of the invention, a plurality of microphones are arranged in the vehicle interior, which respectively pick up the sound of the left ear of the driver, the right ear of the co-driver, the left ear of the left rear passenger and the right ear of the right rear passenger. In this way, a plurality of microphones, i.e., microphones, disposed inside the vehicle may be used to detect sounds in different areas of the vehicle interior, respectively. The microphones are each connected to a data processing device and, during the test, are recorded together or transmitted, in particular wired or wirelessly, to a signal processing unit. Vehicle abnormal noise generally occurs at interior parts of a vehicle and is perceived by the human ears of passengers. The plurality of microphones can acquire abnormal sound signals of areas where different passengers are located according to the arrangement mode. In addition, according to different calculation results of sound signals detected by one or more of the microphones, the abnormal sound at a specific position of the vehicle can be judged, and then the noise source can be checked for the vehicle interior parts near the microphones. Therefore, this embodiment can locate abnormal noise in the vehicle.
Preferably, in a case where the vehicle seat is placed in the middle position of the slide rail with the seat back held upright, the microphones are respectively located at: the height of the seat cushion is 70cm, the distance of the seat cushion is 15cm from the front surface of the headrest, and the distance of the seat cushion is 15cm from the left and right symmetric axes of the headrest. The microphone is close to the position of the ear of the passenger, so that the sound signal collected by the microphone is close to the sound signal heard by the ear of the passenger.
According to one embodiment of the invention, the test conditions are such that the vehicle is travelling at a constant speed on rough and smooth belgium roads at target speeds of 20kph, 25kph, 30kph, 35kph, respectively. The Belgian pavement is a typical convex-concave bad road which is built manually, such as a cobblestone road, a stone road, a twisted road, a washboard road and the like. The rough and smooth Belgian road surfaces refer to non-smooth road surfaces with a greater degree of concavity and convexity and a lesser degree of concavity and convexity, respectively. When the vehicle is running on the belgian road at a low, uniform speed, the belgian road surface provides excitation to the chassis, causing the interior components of the vehicle to make an abnormal sound. In addition, when the vehicle runs at a low speed, because the rotating speed of the engine is low, the sound pressure or the sound pressure level of the noise of the engine is low, and the test of the abnormal sound of the vehicle cannot be influenced.
According to one embodiment of the invention, the GPS is used to monitor that the vehicle has reached the target speed. When the vehicle runs on the belgium road surface at a speed deviating from the target speed, the acoustic characteristics of friction and collision between the vehicle interior parts caused by excitation may change, thereby affecting the comparison result. Therefore, in order to achieve repeatability of the evaluation method, it should be ensured that the vehicle reaches the target speed.
A second aspect of the invention relates to a computer-readable medium, on which a computer program is stored which, when being executed by a processor, carries out the method according to the invention for evaluating the abnormal-sound-characteristic of a vehicle.
According to a third aspect of the present invention, there is provided an evaluation system for vehicle abnormal sound performance, the evaluation system comprising:
-a microphone inside the vehicle for detecting sounds inside the vehicle;
-a signal processing unit for processing the signal output from the microphone, the signal processing unit comprising:
-a transformation module for transforming the signal into the frequency domain to obtain a time-varying spectrum of the preprocessed signal;
-a calculation module for calculating the amount of change of the sound pressure of each point in the time-varying spectrum with respect to its adjacent time interval and adjacent frequency interval;
-an evaluation module for evaluating the abnormal-sound performance of the vehicle based on the variation.
The evaluation system can objectively evaluate the abnormal sound of the vehicle, reduces the interference of human factors to the evaluation result in subjective evaluation, reduces the personnel and time consumption and improves the repeatability of the evaluation result. The evaluation system can be applied to the abnormal sound performance evaluation of various vehicle types. Compared with the prior art that the relative values of acoustic parameters (such as loudness, sharpness, roughness and the like) are directly adopted to evaluate the abnormal sound performance of the vehicle, the evaluation system can evaluate the abnormal sound performance of the vehicle by calculating the relative variation of the sound signals, so that the abnormal sound performance of the vehicle can be closer to the auditory effect of human ears, and a more accurate and practical evaluation effect can be obtained.
According to one embodiment of the invention, the calculation module determines for each point in the time-varying frequency spectrum an average of the sound pressures in a time interval adjacent to the current time of the point and an average of the sound pressures in a frequency interval adjacent to the current frequency of the point, and calculates the change by integrating, in particular weighting, the difference between the sound pressure at the point and these averages, or the calculation module determines for each point in the time-varying frequency spectrum an average of the sound pressures in a time-frequency region adjacent to the point, and calculates the change by taking the difference between the sound pressure at the point and the average.
According to one embodiment of the invention, the transformation module transforms the signal into the frequency domain by means of a fast fourier transform or an auditory model.
The signal processing unit comprises a preprocessing module for preprocessing the signals output from the microphone by means of a weighting network and/or a filter, in particular for filtering signals within 500 Hz.
The embodiments, functions, advantages and effects according to one aspect of the invention also apply in a corresponding manner to the other aspects of the invention.
Drawings
Fig. 1 shows a flowchart of an evaluation method for vehicle abnormal sound performance;
fig. 2 shows a flowchart of another embodiment of an evaluation method for vehicle abnormal sound performance;
fig. 3 shows an evaluation system for vehicle abnormal sound performance;
FIG. 4 illustrates the location of multiple microphones within a vehicle;
FIG. 5a shows a side view of the position of one microphone relative to the vehicle seat;
fig. 5b shows a front view of the position of one microphone relative to the vehicle seat.
Detailed Description
Fig. 1 shows a flowchart of an evaluation method for vehicle abnormal sound performance. The method comprises the following steps:
step S1: under test conditions, sounds inside the vehicle are detected using a microphone disposed inside the vehicle.
Step S2: processing a signal output from the microphone by a signal processing unit, the step comprising:
step S2 a: transforming the signal into the frequency domain to obtain a time-varying frequency spectrum of the preprocessed signal;
step S2 b: the variation of sound pressure of each point in the time-varying frequency spectrum with respect to the adjacent time interval and the adjacent frequency interval is calculated.
Step S3: and evaluating the abnormal sound performance of the vehicle based on the variation.
Preferably, in step S2a, the signal is transformed into the frequency domain by a fast fourier transform or an auditory model.
Preferably, step S2b includes: an average value of the sound pressures within a time interval adjacent to the current time of the point and an average value of the sound pressures within a frequency interval adjacent to the current frequency of the point are determined for each point in the time-varying spectrum, respectively, and the variation is calculated by integrating the difference values of the sound pressures of the point and the average values, or an average value of the sound pressures within a time-frequency region adjacent to the point is determined for each point in the time-varying spectrum, respectively, and the variation is calculated by finding the difference value of the sound pressure of the point and the average value. Specifically, the difference between the sound pressure at the point and the average value of the sound pressures in the adjacent time intervals and the difference between the sound pressure at the point and the average value of the sound pressures in the adjacent frequency intervals are integrated by weighting calculation.
The test conditions according to the invention may be such that the vehicle is travelling at a constant speed on a rough or smooth belgium road surface at a target speed of 20kph, 25kph, 30kph, 35kph respectively. Wherein the vehicle is monitored at said target speed, in particular using GPS.
In step S3, the vehicle abnormal noise performance is determined by comparing with a threshold value set in advance. Here, the abnormal noise performance of the vehicle may be evaluated by taking the maximum value, the average value, the root mean square, and the like of the sound pressure variation amount calculated in S2b over the entire time-varying spectrum, and in particular, the maximum value, the average value, and the root mean square may be compared with a predetermined threshold value. The threshold value is preferably specified in advance by correlating the calculated sound pressure variation with the result of subjective evaluation. For example, the sound pressure variation under the same test condition for the same vehicle successively or simultaneously is associated with the subjective evaluation result, such as building a piecewise function, a lookup table, and the like. Furthermore, other acoustic parameters, such as loudness, a-level, roughness, sharpness, jitter, tone scheduling, etc., detected for the same vehicle under the same test conditions may also be simultaneously taken into the reference range. For example, the sound pressure variation and the corresponding subjective evaluation result are mathematically modeled with reference to the other acoustic parameters. In particular, the neural network model is trained using these data, so that the objective evaluation result can be output by inputting the calculated sound pressure variation amount as an input value into the neural network model, and the evaluation result can correspond to a subjective evaluation result manually performed under the same test conditions, thereby further intelligently evaluating the abnormal sound performance of the vehicle. The signals of the microphone can be analyzed by means of the Relative Approach method in the test analysis software Head ArtemiS SUITE 11.0. The sound pressure of the compression defined therein can be used to evaluate the variation according to the invention and thus the vehicle abnormal sound performance. Further illustratively, the threshold may be set to 3.5cPa for signals within a range of 500Hz-10000 Hz. This means, for example, that the vehicle abnormal noise performance is good below this threshold, and the vehicle abnormal noise performance is poor above this threshold, and it is necessary to perform noise source troubleshooting on the vehicle interior parts near the microphone. If the problem part is locked, the matching size of the problem part and the matching part, the connection mode of the problem part and the matching part, the material types of the problem part and the matching part and the contact surface treatment mode of the problem part and the matching part can be checked.
Fig. 2 shows a flowchart of another embodiment of a method for evaluating the abnormal-sound-level of a vehicle. Here, steps S1 to S3 of the method for evaluating the abnormal-sound-characteristics of the vehicle shown in fig. 1 are also included in fig. 2. The description of these steps is described with reference to fig. 1.
After step S1, a step S4 is additionally included, in which the signal is preprocessed, in particular filtered to within 500Hz, by means of a weighting network and/or a filter, before being transformed into the frequency domain.
Fig. 3 shows an evaluation system 1 for vehicle abnormal sound performance, the system 1 including:
a microphone 2 inside the vehicle for detecting sounds inside the vehicle;
a signal processing unit 3 for processing the signals output from the microphones, the signal processing unit comprising:
-a transformation module 31 for transforming the signal into the frequency domain to obtain a time-varying spectrum of the preprocessed signal;
a calculation module 32 for calculating the variation of the sound pressure of each point in the time-varying spectrum with respect to its adjacent time interval and adjacent frequency interval;
an evaluation module 33 for evaluating the abnormal-sound performance of the vehicle based on the variation.
In a preferred embodiment, the signal processing unit 3 further comprises a preprocessing module 34, which is used to preprocess the signals output from the microphone by means of a weighting network and/or a filter, in particular to filter out signals within 500 Hz.
It is also preferred that the calculation module 32 determines for each point in the time-varying frequency spectrum an average of the sound pressures in a time interval adjacent to the current time of the point and an average of the sound pressures in a frequency interval adjacent to the current frequency of the point, respectively, and calculates the change by integrating, in particular weighting, the difference between the sound pressure of the point and these averages, or that the calculation module 32 determines for each point in the time-varying frequency spectrum an average of the sound pressures in a time-frequency region adjacent to the point, respectively, and calculates the change by taking the difference between the sound pressure of the point and the average.
It is also preferred that the transformation module 31 transforms the signal into the frequency domain by means of a fast fourier transform or an auditory model.
Fig. 4 shows the positions of a plurality of microphones 11 in the vehicle. The plurality of microphones 11 collect sounds of the left ear of the driver, the right ear of the co-driver, the left ear of the left rear passenger, and the right ear of the right rear passenger, respectively. Vehicle abnormal noise generally occurs in interior parts of a vehicle and is perceived by the human ears of passengers. The plurality of microphones can pick up abnormal sound signals of the area where the passenger is located according to the arrangement in fig. 4.
Fig. 5a shows a side view of the position of one of the microphones 11 relative to the vehicle seat 2. Fig. 5b shows a front view of the position of the microphone 11 in fig. 5a relative to the vehicle seat 2. In the case where the vehicle seat 2 is placed in the middle position of the slide rail with the seat back held upright, the microphones 11 are respectively located at: a height of 70cm from the seat cushion, a distance of 15cm from the front surface of the headrest, and a distance of 15cm from the bilateral symmetry axis of the headrest. The microphone is close to the position of the ear of the passenger, so that the sound signal collected by the microphone is close to the sound signal heard by the ear of the passenger. The position of the microphone 11 relative to the seat 2 can be adjusted according to the height, posture, etc. of the occupant in the vehicle so that the sensor 11 is close to the position of the human ear.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.
Claims (15)
1. An evaluation method for vehicle abnormal sound performance, the method comprising the steps of:
-detecting sounds inside the vehicle under test conditions using a microphone arranged inside the vehicle;
-processing the signal output from the microphone by a signal processing unit comprising:
-transforming the signal into the frequency domain to obtain a time-varying spectrum of the preprocessed signal; and is
-calculating the amount of change in sound pressure for each point in the time-varying spectrum with respect to its adjacent time interval and adjacent frequency interval;
-evaluating the abnormal-sound performance of the vehicle based on the variation amount.
2. The method of claim 1, wherein calculating the amount of change in sound pressure for each point in the time-varying spectrum relative to its adjacent time interval and/or adjacent frequency interval comprises:
-determining for each point in the time-varying frequency spectrum an average of the sound pressures within a time interval adjacent to the current time of the point and an average of the sound pressures within a frequency interval adjacent to the current frequency of the point, respectively, and calculating the variation by integrating the difference of the sound pressure of the point and these averages, or
-determining for each point in the time-varying frequency spectrum an average of the sound pressures within the time-frequency region adjacent to the point, and calculating the variation by taking the difference between the sound pressure at the point and the average.
3. The evaluation method according to claim 2, wherein the difference between the sound pressure at the point and the average value of the sound pressures in the adjacent time intervals is integrated by weighting the difference between the sound pressure at the point and the average value of the sound pressures in the adjacent frequency intervals.
4. An evaluation method according to one of claims 1 to 3, characterized in that the signal is transformed into the frequency domain by a fast Fourier transform or an auditory model.
5. Evaluation method according to one of claims 1 to 4, characterized in that the signals are preprocessed, in particular filtered to within 500Hz, by means of a weighting network and/or a filter before the signals are transformed into the frequency domain.
6. The evaluation method according to one of claims 1 to 5, characterized in that a plurality of microphones are provided in the vehicle interior, the microphones picking up sounds of the driver's left ear, the co-driver's right ear, the left rear passenger's left ear, and the right rear passenger's right ear, respectively.
7. The evaluation method according to claim 6, wherein the microphones are respectively located at: a height of 70cm from the seat cushion, a distance of 15cm from the front surface of the headrest, and a distance of 15cm from the bilateral symmetry axis of the headrest.
8. The evaluation method according to one of claims 1 to 7, wherein the test condition is that the vehicle travels at a constant speed on a rough or smooth Belgian road surface at a target speed of 20kph, 25kph, 30kph, 35kph, respectively.
9. The evaluation method according to claim 8, wherein GPS is used to monitor that the vehicle is at the target speed.
10. The evaluation method according to any one of claims 1 to 9, wherein the vehicle abnormal-sound performance is determined by comparison with a preset threshold value.
11. Computer-readable medium, on which a computer program is stored, which, when being executed by a processor, carries out the method for evaluating vehicle abnormal noise performance according to one of claims 1 to 10.
12. An evaluation system for vehicle abnormal sound performance, the system comprising:
-a microphone inside the vehicle for detecting sounds inside the vehicle;
-a signal processing unit for processing the signal output from the microphone, the signal processing unit comprising:
-a transformation module for transforming the signal into the frequency domain to obtain a time-varying spectrum of the preprocessed signal;
-a calculation module for calculating the amount of change of the sound pressure of each point in the time-varying spectrum with respect to its adjacent time interval and adjacent frequency interval;
-an evaluation module for evaluating the abnormal-sound performance of the vehicle based on the variation.
13. The evaluation system according to claim 12,
-the calculation module determines, for each point in the time-varying spectrum, the mean value of the sound pressures within a time interval adjacent to the current time of the point and the mean value of the sound pressures within a frequency interval adjacent to the current frequency of the point, respectively, and calculates the variation by integrating, in particular weighting, the difference of the sound pressures of the point and these mean values, or
The calculation module determines, for each point in the time-varying frequency spectrum, an average of the sound pressures within the time-frequency region adjacent to the point, and calculates the variation by taking the difference from the sound pressure of the point and the average.
14. The evaluation system according to claim 12 or 13, wherein the transformation module transforms the signal into the frequency domain by a fast fourier transform or an auditory model.
15. The evaluation system according to one of claims 12 to 14, wherein the signal processing unit comprises a preprocessing module for preprocessing the signal output from the microphone by means of a weighting network and/or a filter, in particular filtering out signals within 500 Hz.
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