Air conditioner duct acoustic testing device

Abstract

The application provides an air conditioner air pipe acoustic testing device, and belongs to the technical field of testing. The method comprises the following steps: a first impedance pipe, a second impedance pipe, a microphone, a data collector and a signal processor. The first impedance pipe and the second impedance pipe are arranged at two ends of a measured air conditioner air pipe respectively. A sound source is arranged at a first end of the first impedance pipe. A first output end of the data collector is used for outputting a voltage signal to drive the sound source to output a sound wave signal. The first impedance pipe and the second impedance pipe are respectively provided with the microphone on the pipe wall or in the pipe. The output end of the microphone is connected to the signal processor through the data collector. The signal processor is used for calculating the transmission loss of the measured air conditioner air pipe based on the output data of the microphone in a first state and the output data of the microphone in a second state, and obtaining the acoustic testing result of the measured air conditioner air pipe. The air conditioner air pipe acoustic testing device provided by the application can reduce the testing cost and improve the testing precision.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of testing, in particular to an air conditioner air duct acoustic testing device. BACKGROUND

[0002] Under the trend of automobile intelligence and electrification, the in-vehicle vibration and noise performance (NVH) performance has become the core index of consumer attention. As the key channel for airflow and noise transmission, the transmission loss characteristics of the air conditioner air duct directly determine the in-vehicle acoustic comfort. For the transmission loss of the air conditioner air duct, the existing testing methods include two sound source method and pulse method. The two sound source method requires two sound sources, and the performance of the two sound sources needs to be consistent. If the sound source is unstable, it will cause measurement error. The pulse method requires that the pipeline has no reflection, and requires a very long pipeline, which is difficult to realize. Moreover, the pulse method relies on short-time strong signal acquisition, and is greatly affected by environmental noise. SUMMARY

[0003] The embodiment of the present application provides an air conditioner air duct acoustic testing device, which can reduce the testing cost and improve the testing precision.

[0004] The embodiment of the present application provides an air conditioner air duct acoustic testing device, which can reduce the testing cost and improve the testing precision.

[0005] The first end of the first impedance tube is provided with a sound source, the first output end of the data acquisition device is used for outputting a voltage signal to drive the sound source to output a sound wave signal, the second end of the first impedance tube is used for connecting with the first end of the measured air conditioner air duct, the first end of the second impedance tube is used for connecting with the second end of the measured air conditioner air duct, and the wall or the inside of each of the first impedance tube and the second impedance tube is provided with the microphone.

[0006] The output end of the microphone is connected with the signal input end of the data acquisition device, the second output end of the data acquisition device is connected with the signal input end of the signal processor, and the signal processor is used for:

[0007] Based on the output data of the microphone in the first state and the output data of the microphone in the second state, the transmission loss of the measured air conditioner air duct is calculated to obtain the acoustic testing result of the measured air conditioner air duct.

[0008] Wherein, in the first state, the second end of the second impedance tube is provided with sound absorption material, and in the second state, the second end of the second impedance tube is not provided with sound absorption material.

[0009] In one exemplary embodiment of this application, the microphone includes a first microphone, a second microphone, a third microphone, and a fourth microphone; the first microphone and the second microphone are disposed on the tube wall or inside the first impedance tube, and the third microphone and the fourth microphone are disposed on the tube wall or inside the second impedance tube.

[0010] The signal processor is specifically used for:

[0011] The transmission loss of the tested air conditioning duct is calculated using the first formula; the first formula is:

[0012] ;

[0013] in, ;

[0014] ;

[0015] ;

[0016] ;

[0017] in, To transmit the loss, The transmittance is the coefficient of light. , , , They are respectively The sound pressure data measured by the four microphones under the given conditions. Or 2, Indicates the first state. Indicates the second state. , These are the distances from the first microphone and the second microphone to the first end face of the air conditioning duct being tested, respectively. , These are the distances from the third and fourth microphones to the second end face of the tested air conditioning duct, respectively. for Incident wave in the state, for Transmitted waves in a certain state for The reflected wave of the second impedance tube in the state, The wave number represents the sound wave signal. This is the imaginary part.

[0018] In one exemplary embodiment of this application, the signal processor is further configured to:

[0019] determine an adjustment parameter based on the reflection coefficient of the sound absorption material, the adjustment parameter and the reflection coefficient being in a negative correlation relationship;

[0020] correct the transmission loss based on the adjustment parameter.

[0021] In an exemplary embodiment of the present application, the signal processor is specifically further configured to:

[0022] determine a proportional parameter based on the reflection coefficient of the sound absorption material;

[0023] determine the adjustment parameter based on the reflection coefficient of the sound absorption material and the proportional parameter.

[0024] In an exemplary embodiment of the present application, a test hole is arranged on the wall of the first impedance tube, and the microphone is arranged in the test hole.

[0025] In an exemplary embodiment of the present application, the number of microphones arranged on the wall of the first impedance tube is two, and the number of test holes arranged on the wall of the first impedance tube is at least two.

[0026] In an exemplary embodiment of the present application, the air conditioner duct acoustic testing device further comprises:

[0027] The spacing between the test holes is different for different apertures of the measured air conditioner duct.

[0028] In an exemplary embodiment of the present application, the first impedance tube and the measured air conditioner duct, and the second impedance tube and the measured air conditioner duct are connected through a test tool.

[0029] In an exemplary embodiment of the present application, a power amplifier is arranged between the first output end of the data collector and the sound source.

[0030] In an exemplary embodiment of the present application, the air conditioner duct acoustic testing device further comprises:

[0031] a test chamber; wherein the first impedance tube, the second impedance tube, the microphone, the data collector and the signal processor are arranged in the test chamber.

[0032] The air conditioner duct acoustic testing device provided by the embodiments of the present application has the following beneficial effects:

[0033] The embodiments of the present application form two different acoustic load conditions by arranging the sound absorption material (first state) at the end (second end) of the second impedance tube and not arranging the sound absorption material (second state), calculate the transmission loss according to the sound pressure data collected by the microphone in the two states, and improve the precision of the acoustic testing of the measured air conditioner duct.

[0034] Compared with the existing double sound source method, the method of the embodiment of the application only needs one sound source, reduces the equipment cost and the difficulty of synchronous control, and avoids the error caused by the inconsistency of the sound source; compared with the existing pulse method, the method of the embodiment of the application does not need a very long pipeline, has a compact structure, is suitable for laboratory and field testing, and the method of the embodiment can reduce the influence of environmental noise and improve the reliability of the test result through differential processing under two load conditions. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 is a structural schematic diagram of an air conditioner air pipe acoustic test device provided by the embodiment of the application;

[0037] Figure 2 is a flowchart of an air conditioner air pipe acoustic test method provided by the embodiment of the application;

[0038] Figure 3 is a schematic diagram of a transmission loss curve provided by the embodiment of the application;

[0039] In the drawings:

[0040] 1-power amplifier, 2-loudspeaker, 3-first impedance tube, 4-first microphone, 5-test hole, 6-second microphone, 7-test tooling, 8-air conditioner air pipe to be tested, 9-second impedance tube, 10-third microphone, 11-fourth microphone, 12-data acquisition device, 13-signal processing software, 14-test chamber. DETAILED DESCRIPTION

[0041] In order to enable personnel in the technical field to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0042] The term "include", along with other any variants such as "includes" or "including", as used in the specification and in the claims of the present application, shall not be construed so as to mean "consist only of", unless specifically stated otherwise. In addition, the terms "first", "second", and the like, are used only to distinguish different objects, and are not used to describe a particular order.

[0043] The implementation of the present application is described in detail below in conjunction with specific drawings:

[0044] Figure 1 A structural schematic diagram of an air conditioner air pipe acoustic testing device provided by an embodiment of the present application is shown in FIG. 1. Figure 1 The air conditioner air pipe acoustic testing device includes a first impedance tube 3, a second impedance tube 9, a microphone, a data collector 12, and a signal processor.

[0045] A sound source is arranged at the first end of the first impedance tube 3, and the first output end of the data collector 12 is used to output a voltage signal to drive the sound source to output a sound wave signal. The second end of the first impedance tube 3 is used to be connected with the first end of the measured air conditioner air pipe 8. The first end of the second impedance tube 9 is used to be connected with the second end of the measured air conditioner air pipe 8. The microphone is arranged on the wall or inside of each of the first impedance tube 3 and the second impedance tube 9.

[0046] The output end of the microphone is connected with the signal input end of the data collector 12. The second output end of the data collector 12 is connected with the signal input end of the signal processor. The signal processor is used to:

[0047] Based on the output data of the microphone in the first state and the output data of the microphone in the second state, the transmission loss of the measured air conditioner air pipe 8 is calculated to obtain the acoustic testing result of the measured air conditioner air pipe 8.

[0048] In the first state, the second end of the second impedance tube 9 is provided with sound absorption material. In the second state, the second end of the second impedance tube 9 is not provided with sound absorption material.

[0049] In the present embodiment, the first impedance tube 3 and the second impedance tube 9 are arranged at the front end and the rear end of the measured air conditioner air pipe 8, respectively. A sound source (for example, a loudspeaker 2) is arranged at the front end (the first end) of the first impedance tube 3. By setting the parameters of the data collector 12, a voltage signal of a specified level can be output at the first output end of the data collector 12. The voltage signal can drive the sound source inside the first impedance tube 3 to output a sound wave signal (plane wave sound field).

[0050] Meanwhile, the pipe wall or the interior of the first impedance tube 3 and the pipe wall or the interior of the second impedance tube 9 are provided with microphones (ICP microphones) for detecting the sound pressure data of the corresponding positions and sending the sound pressure data to the signal input end of the data collector 12. The end (second end) of the second impedance tube 9 is provided with sound-absorbing material, so that the end of the second impedance tube 9 forms a non-reflective end (first state). The end (second end) of the second impedance tube 9 is not provided with sound-absorbing material, so that the end of the second impedance tube 9 forms a rigid end (second state). After the sound pressure data collected by the microphones in the two states is sent to the signal input end of the data collector 12, the sound pressure data is sent to the signal processor through the second output end of the data collector 12.

[0051] The signal processor can be implemented by the signal processing software 13 in the computer 14, and the signal processor differentiates the sound pressure data collected by the microphones in the two states to obtain the transmission loss of the measured air conditioner duct 8, that is, the acoustic test result of the measured air conditioner duct 8. Figure 1

[0052] It can be seen from the above that, by providing the sound-absorbing material at the end (second end) of the second impedance tube 9 (first state) and not providing the sound-absorbing material (second state), two different acoustic load conditions are formed, the transmission loss is calculated according to the sound pressure data collected by the microphones in the two states, and the accuracy of the acoustic test of the measured air conditioner duct 8 is improved.

[0053] Compared with the existing double sound source method, the method of the embodiment only needs one sound source, reduces the equipment cost and the difficulty of synchronous control, and avoids the error caused by the inconsistency of the sound sources. Compared with the existing pulse method, the method of the embodiment has a compact structure and is suitable for laboratory and field tests, and improves the reliability of the test results.

[0054] In an exemplary embodiment of the present application, the microphones include a first microphone 4, a second microphone 6, a third microphone 10, and a fourth microphone 11; the first microphone 4 and the second microphone 6 are arranged on the pipe wall or in the interior of the first impedance tube 3, and the third microphone 10 and the fourth microphone 11 are arranged on the pipe wall or in the interior of the second impedance tube 9.

[0055] The signal processor is specifically used for:

[0056] calculating the transmission loss of the measured air conditioner duct 8 by the first formula; the first formula is:

[0057] ;

[0058] wherein, ;

[0059] ;

[0060] ​ ;

[0061] ;

[0062] in, To transmit the loss, The transmittance is the coefficient of light. , , , They are respectively The sound pressure data measured by the four microphones under the given conditions. Or 2, Indicates the first state. Indicates the second state. , These are the distances from the first microphone 4 and the second microphone 6 to the first end face of the air conditioning duct 8 being tested, respectively. , These are the distances from the third microphone 10 and the fourth microphone 11 to the second end face of the air conditioning duct 8 being tested, respectively. for Incident wave in the state, for Transmitted waves in a certain state for The reflected wave of the second impedance tube 9 in the state, The wave number represents the sound wave signal. This is the imaginary part.

[0063] In this embodiment, four microphones are used, respectively positioned at corresponding locations on the first impedance tube 3 and the second impedance tube 9. The sound wave signal emitted by the sound source is transmitted between the first impedance tube 3, the air conditioning duct 8 under test, and the second impedance tube 9. The incident wave can be obtained based on the sound pressure data measured by the four microphones. The reflected wave of the first impedance tube 3 Transmitted waves The reflected wave of the second impedance tube 9 The above signals satisfy the following transfer matrix:

[0064] ;

[0065] in, , , , Represents the elements in the transfer matrix. for The reflected wave from the first impedance tube 3 in the state, according to the definition of transmission loss, when the end of the second impedance tube 9 is the non-reflective end (i.e. When, based on the incident wave and transmitted waves The ratio determines the transmission loss.

[0066] At the same time, due to hour, Therefore, we obtain the following relation:

[0067] ;

[0068] For the two load configurations (non-reflective end and rigid reflective end) at the end of the second impedance tube 9, the following two sets of equations are obtained:

[0069] System of equations 1:

[0070] ;

[0071] System of Equations 2:

[0072] ;

[0073] By solving the two systems of equations above, we can find:

[0074] ;

[0075] Therefore, the formula for calculating the propagation loss is:

[0076] .

[0077] In one exemplary embodiment of this application, the signal processor is further configured to:

[0078] The adjustment parameters are determined based on the reflection coefficient of the sound-absorbing material, and the adjustment parameters and the reflection coefficient are negatively correlated.

[0079] The transmission loss is corrected based on the adjusted parameters.

[0080] In this embodiment, in the first state, theoretically, the sound-absorbing material is required to completely absorb the sound waves (reflection coefficient γ=0) to simulate a "no-reflection" environment. In actual testing, if the sound absorption coefficient of the sound-absorbing material is insufficient (especially in the low-frequency range), it will cause residual reflected waves at the end of the second impedance tube 9. The residual reflected waves will propagate in the opposite direction and interact with the incident wave. and transmitted waves Superposition forms a standing wave, making the incident wave and transmitted waves The value deviates from the true value (is too large), which leads to the calculation error of the transmission loss.

[0081] To solve the above problems, the embodiment corrects the transmission loss by setting an adjustment parameter. Specifically, it is considered that the size of the residual reflected wave is mainly related to the reflection coefficient of the sound-absorbing material. The greater the reflection coefficient of the sound-absorbing material, the greater the residual reflected wave. At the same time, it is considered that the measured air conditioner air pipe 8 has an attenuation effect on the sound wave, and the influence degree of the residual reflected wave on the incident wave is smaller than that on the transmitted wave, that is, the deviation degree of the transmitted wave from the true value is greater. According to the calculation formula of the transmission loss, the residual reflected wave will cause the absolute value of the transmission loss to be calculated too large.

[0082] Therefore, the embodiment first determines the adjustment parameter based on the reflection coefficient of the sound-absorbing material. The greater the reflection coefficient, the smaller the adjustment parameter, so as to offset the influence of the residual reflected wave.

[0083] From the above, it can be concluded that the embodiment considers the influence of the end reflection of the second impedance tube 9 on the calculation of the transmission loss, determines the corresponding adjustment parameter based on the reflection coefficient of the sound-absorbing material, corrects the transmission loss, and makes the calculation result of the transmission loss more accurate.

[0084] In an exemplary embodiment of the present application, the signal processor is specifically further used for:

[0085] determining a proportional parameter based on the reflection coefficient of the sound-absorbing material;

[0086] determining the adjustment parameter based on the reflection coefficient of the sound-absorbing material and the proportional parameter.

[0087] In the embodiment, it is considered that different reflection coefficients of different sound-absorbing materials have different influences on the transmission loss. The embodiment sets a proportional parameter to quantify the influence of the reflection coefficient of the sound-absorbing material on the transmission loss.

[0088] Specifically, determining the proportional parameter based on the reflection coefficient of the sound-absorbing material can be detailed as follows:

[0089] If the reflection coefficient of the sound-absorbing material is less than a first threshold value, the proportional parameter is determined as a first numerical value;

[0090] If the reflection coefficient of the sound-absorbing material is between the first threshold value and a second threshold value, the proportional parameter is determined as a second numerical value;

[0091] If the reflection coefficient of the sound-absorbing material is greater than the second threshold value, the proportional parameter is determined as a third numerical value; the first threshold value is less than the second threshold value, and the first numerical value, the second numerical value and the third numerical value increase in turn.

[0092] ​​​​In the embodiment, when the reflection coefficient of the sound-absorbing material is less than the first threshold (for example, 0.2), it can be considered that the sound-absorbing material completely absorbs the sound wave, and there is no reflected wave at the end of the second impedance tube 9, and the corresponding proportional parameter can be set to 0.

[0093] When the reflection coefficient of the sound-absorbing material is between the first threshold and the second threshold (for example, 0.5), the residual reflected wave energy cannot be ignored, and at this time, the proportional parameter can be set to a smaller second value (for example, 0.1).

[0094] When the reflection coefficient of the sound-absorbing material is greater than the second threshold (for example, 0.7), the sound-absorbing material has poor performance, and the residual reflected wave energy is high, and at this time, the proportional parameter can be set to a larger third value (for example, 0.5).

[0095] On this basis, the adjustment parameter can be determined based on the reflection coefficient of the sound-absorbing material and the proportional parameter, and can include:

[0096] The adjustment parameter is calculated by a second formula, and the second formula is:

[0097] ;

[0098] Wherein, represents the adjustment parameter, represents the proportional parameter, represents the reflection coefficient of the sound-absorbing material.

[0099] Finally, the corrected transmission loss is:

[0100] ;

[0101] From the above, the proportional parameter corresponding to the reflection coefficient of the sound-absorbing material is determined in the embodiment, the dynamic correction of the transmission loss is realized, and the accuracy of the transmission loss calculation is further improved.

[0102] In an exemplary embodiment of the present application, a test hole 5 is arranged on the wall of the first impedance tube 3, and a microphone is arranged in the test hole 5.

[0103] In the embodiment, the test hole 5 can be arranged on the wall of the first impedance tube 3, and the corresponding microphone is fixed in the test hole 5 to realize the fixation of the microphone on the first impedance tube 3. The signal collection end of the microphone is located inside the first impedance tube 3, and is used to measure the sound pressure signal inside the first impedance tube 3. The output end of the microphone is connected to the data collector 12, and the detected data is sent to the data collector 12.

[0104] Similarly, the test holes 5 can also be arranged on the wall of the second impedance tube 9, and the corresponding microphones are fixed in the test holes 5 to realize the fixation of the microphones on the second impedance tube 9. The signal collection end of the microphone is located inside the second impedance tube 9, and is used to measure the sound pressure signal inside the second impedance tube 9. The output end of the microphone is connected to the data collector 12, and the detected data is sent to the data collector 12.

[0105] The above-described arrangement method of the microphone is simple in operation and easy to implement.

[0106] In an exemplary embodiment of the present application, the number of microphones arranged on the wall of the first impedance tube 3 is two, and the number of test holes 5 arranged on the wall of the first impedance tube 3 is at least two.

[0107] In the embodiment, two microphones (including the first microphone 4 and the second microphone 6) are arranged on the wall of the first impedance tube 3, and the number of corresponding test holes 5 can be more than two. The plurality of test holes 5 are arranged in a straight line on the first impedance tube 3. By arranging the microphones in different test holes 5, the position of the microphone can be changed, and the testing of multiple groups of data is facilitated.

[0108] Similarly, two microphones (including the third microphone 10 and the fourth microphone 11) are arranged on the wall of the second impedance tube 9, and the number of corresponding test holes 5 can be more than two. The plurality of test holes 5 are arranged in a straight line on the second impedance tube 9. By arranging the microphones in different test holes 5, the position of the microphone can be changed, and the testing of multiple groups of data is facilitated.

[0109] It should be noted that if no microphone is arranged in a certain test hole 5, the test hole 5 needs to be plugged to avoid the leakage of sound wave signals and affect the test results.

[0110] In an exemplary embodiment of the present application, the air conditioner duct acoustic testing device further comprises:

[0111] The spacing between the test holes 5 is different for different aperture air conditioner ducts 8 to be tested.

[0112] In the embodiment, the spacing between the plurality of test holes 5 is different for different aperture air conditioner ducts 8 to be tested, so as to ensure different limited frequency bandwidths. For example, according to different aperture air conditioner ducts 8 to be tested, the spacing between the test holes 5 can be set to 20mm or 50mm.

[0113] In an exemplary embodiment of the present application, the first impedance tube 3 and the air conditioner duct 8 to be tested, and the second impedance tube 9 and the air conditioner duct 8 to be tested are connected through the test tooling 7.

[0114] In the embodiment, the end of the test tool 7 connected with the first impedance tube 3 is designed as a circle according to the actual size of the first impedance tube 3, and the end of the test tool 7 connected with the measured air conditioner air duct 8 is designed as a square according to the actual size of the measured air conditioner air duct 8; the end of the test tool 7 connected with the second impedance tube 9 is designed as a circle according to the actual size of the second impedance tube 9, and the end of the test tool 7 connected with the measured air conditioner air duct 8 is designed as a square according to the actual size of the measured air conditioner air duct 8; the length of the test tool 7 is greater than or equal to 6 times the diameter of the impedance tube (the first impedance tube 3 and the second impedance tube 9), so as to avoid the result error caused by the test tool in the test process.

[0115] As can be seen from the above, the test tool 7 is arranged in the embodiment, so as to realize the reliable connection between the first impedance tube 3 and the measured air conditioner air duct 8 and the reliable connection between the second impedance tube 9 and the measured air conditioner air duct 8.

[0116] In an exemplary embodiment of the present application, a power amplifier 1 is arranged between the first output end of the data collector 12 and the sound source.

[0117] In the embodiment, the power amplifier 1 is used to receive the voltage signal output by the data collector 12 and amplify the voltage signal, so as to realize the reliable driving of the sound source.

[0118] In an exemplary embodiment of the present application, the air conditioner air duct acoustic test device further comprises:

[0119] A test chamber 14; wherein the first impedance tube 3, the second impedance tube 9, the microphones, the data collector 12 and the signal processor are all arranged in the test chamber 14.

[0120] In the embodiment, the test chamber 14 is a semi-anechoic chamber, which ensures that the environmental background noise is not greater than 25 dB(A), and is beneficial to improve the accuracy of the test.

[0121] With reference to Figure 2 Based on the above test device, the air conditioner air duct acoustic test can be performed by the following steps:

[0122] (1) Fix the power amplifier 1 and the data collector 12 on the rack, and place the four microphones in the test hole 5;

[0123] (2) Start the power amplifier 1, and after the sound source signal is stable, set the range and test frequency range;

[0124] (3) Perform the microphone amplitude calibration to obtain the accurate microphone sensitivity value; form a non-reflection end at the end of the second impedance tube 9, perform the amplitude mismatch and phase amplitude calibration between the microphones, and perform the phase amplitude calibration by using the microphone and the data collector 12;

[0125] (4) Connect the test fixture 7 to the first end and the second end of the air conditioning duct 8 under test respectively, connect the first impedance tube 3 and the second impedance tube 9 to the corresponding test fixture 7, and form a rigid end and a non-reflection end at the end of the second impedance tube 9 respectively. Use the double load method to test and obtain test data.

[0126] (5) Upload the test data to the signal processing software 13, and the signal processing software 13 calculates the transmission loss according to the first formula;

[0127] (6) The transmission loss curve can be obtained by using the above test steps, such as Figure 3 As shown, this transmission loss curve illustrates how transmission loss changes with frequency. The horizontal axis represents the frequency of the acoustic signal, and the vertical axis represents the transmission loss at each frequency.

[0128] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An acoustic testing device for air conditioning ducts, characterized in that, It includes a first impedance tube, a second impedance tube, a microphone, a data acquisition unit, and a signal processor; A sound source is provided at the first end of the first impedance tube, and the first output end of the data acquisition unit is used to output a voltage signal to drive the sound source to output a sound wave signal. The second end of the first impedance tube is used to connect to the first end of the air conditioner duct under test, and the first end of the second impedance tube is used to connect to the second end of the air conditioner duct under test. The microphone is provided on the tube wall or inside of the first impedance tube and the second impedance tube respectively. The output terminal of the microphone is connected to the signal input terminal of the data acquisition unit, and the second output terminal of the data acquisition unit is connected to the signal input terminal of the signal processor. The signal processor is used for: Based on the microphone output data in the first state and the microphone output data in the second state, the transmission loss of the tested air conditioning duct is calculated, and the acoustic test results of the tested air conditioning duct are obtained. In the first state, the second end of the second impedance tube is provided with sound-absorbing material, and in the second state, the second end of the second impedance tube is not provided with sound-absorbing material. The microphone includes a first microphone, a second microphone, a third microphone, and a fourth microphone; the first microphone and the second microphone are disposed on the tube wall or inside the first impedance tube, and the third microphone and the fourth microphone are disposed on the tube wall or inside the second impedance tube. The signal processor is specifically used for: The transmission loss of the tested air conditioning duct is calculated using the first formula; the first formula is: ； in, ; ； ； ； in, To transmit the loss, The transmittance is the coefficient of light. , , , They are respectively The sound pressure data measured by the four microphones under the given conditions. Or 2, Indicates the first state. Indicates the second state. , These are the distances from the first microphone and the second microphone to the first end face of the air conditioning duct being tested, respectively. , These are the distances from the third and fourth microphones to the second end face of the tested air conditioning duct, respectively. for Incident wave in the state, for Transmitted waves in a certain state for The reflected wave of the second impedance tube in the state, The wave number represents the sound wave signal. It is the imaginary part; The signal processor is also used for: The adjustment parameters are determined based on the reflection coefficient of the sound-absorbing material, and the adjustment parameters and the reflection coefficient are negatively correlated. The transmission loss is corrected based on the adjustment parameters; The signal processor is also used for: Determine the proportional parameters based on the reflection coefficient of the sound-absorbing material; The adjustment parameters are determined based on the reflection coefficient of the sound-absorbing material and the proportional parameters. In determining the proportional parameters based on the reflection coefficient of the sound-absorbing material, the signal processor is used to: If the reflection coefficient of the sound-absorbing material is less than the first threshold, the proportional parameter is set to the first value; If the reflection coefficient of the sound-absorbing material is between the first threshold and the second threshold, the proportional parameter is determined to be the second value; If the reflection coefficient of the sound-absorbing material is greater than the second threshold, the proportional parameter is determined to be the third value; if the first threshold is less than the second threshold, the first value, the second value, and the third value increase sequentially. When determining the adjustment parameters based on the reflection coefficient and scaling parameters of the sound-absorbing material, the signal processor is used to: The adjustment parameters are calculated using the second formula, which is: ； in, This indicates that the parameters are being adjusted. Indicates the proportional parameter. This represents the reflection coefficient of the sound-absorbing material; The final corrected propagation loss is: 。 2. The acoustic testing device for air conditioning ducts as described in claim 1, characterized in that, A test hole is provided on the wall of the first impedance tube, and the microphone is disposed in the test hole.

3. The acoustic testing device for air conditioning ducts as described in claim 2, characterized in that, The first impedance tube has two microphones installed on its wall, and the first impedance tube has at least two test holes installed on its wall.

4. The acoustic testing device for air conditioning ducts as described in claim 3, characterized in that, Also includes: The spacing between the test holes varies for air conditioning ducts with different apertures.

5. The acoustic testing device for air conditioning ducts as described in claim 1, characterized in that, The first impedance tube and the air conditioning duct under test, as well as the second impedance tube and the air conditioning duct under test, are connected by a test fixture.

6. The acoustic testing device for air conditioning ducts as described in claim 1, characterized in that, A power amplifier is provided between the first output terminal of the data acquisition device and the sound source.

7. The acoustic testing device for air conditioning ducts as described in claim 1, characterized in that, Also includes: The test chamber; wherein the first impedance tube, the second impedance tube, the microphone, the data acquisition unit and the signal processor are all located in the test chamber.

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