Exterior noise reproduction system

Abstract

An external noise reproduction system can create a realistic external sound field environment in a ground-based laboratory, simulating the external noise of aircraft, high-speed trains, buses, and other high-speed vehicles. This system is used by designers and developers to conduct sound insulation performance tests on wall panels and can also facilitate maintenance personnel in locating faults in the wall panel structure. The system includes: an equidistant measurement and control surface construction system, which can perform three-dimensional spatial scanning of the object under test, identify its surface morphology, and establish an equidistant curved surface model that closely resembles the surface morphology of the object under test; an array-type sound source system that emits white noise excitation; a curved microphone array that surrounds the object under test to collect and monitor noise signals; and a control system that is communicatively connected to the array-type sound source system and the curved microphone array to obtain excitation response and control the array-type sound source system and the curved microphone array.

Description

Technical Field

[0001] This invention relates to an external noise reproduction system. Background Technology

[0002] The cabin noise level of civil aircraft is closely related to the passenger experience. A good cabin noise level not only makes passengers feel comfortable, but also makes pilots feel relaxed, enables crew members to work efficiently and accurately, slows down equipment aging, and directly or indirectly ensures the safety of the aircraft and cabin crew. Civil aircraft cabin noise has multiple sources, such as engines, turbulent boundary layers, environmental control systems, and electronic equipment. Among these, external sound sources such as turbulent boundary layer noise and engine noise are the main sources of cabin noise and persist throughout the flight, having a significant impact on the cabin sound field.

[0003] The main method for studying the acoustic field inside an aircraft cabin is to improve the cabin acoustic environment by increasing the sound insulation and absorption of the aircraft's panels. Traditionally, cabin noise data is collected during flight tests, followed by laboratory analysis and sound quality evaluation. However, flight tests are costly and lengthy, making it impossible to test and compare different sound insulation structures in a single test flight.

[0004] In recent years, research methods for cabin sound field reconstruction have been gradually applied. For example, CN111770429B discloses a multi-channel equalization feedback method for aircraft cabin sound field reproduction system and method. In this patent, a loudspeaker array is placed inside the aircraft cabin section to simulate cabin noise under different operating conditions during aircraft flight, which is used for cabin acoustic research.

[0005] Furthermore, in the paper "Experiments of multi-channel least-square methods for sound field reproduction inside aircraftmock-up: Objective evaluations" published by Canadian scholars P.-A. Gauthier et al., a combination of loudspeaker arrays and exciter arrays was used to reproduce the cabin sound field. While the aforementioned aircraft cabin noise reproduction technology can be used to assess cabin noise levels and evaluate sound quality, it cannot infer the sound absorption and insulation performance of the aircraft panels from the cabin sound field. Therefore, it still has certain limitations in improving the acoustic performance of aircraft panels and enhancing the cabin acoustic environment.

[0006] In addition, using impedance tubes to conduct acoustic tests on aircraft panel materials can only obtain the acoustic performance of a single material sample. Studies on panel sound insulation based on partial aircraft panels cannot fully encompass special structures such as cabin windows, trusses, and luggage racks. Therefore, the results of the studies cannot accurately characterize the overall sound insulation effect of aircraft panels.

[0007] Therefore, it is necessary to conduct large-scale sound insulation research based on aircraft engineering prototypes. How to create a realistic external sound field environment in a ground test laboratory is the first step in carrying out such research and is also a technical problem that urgently needs to be solved. Summary of the Invention

[0008] This invention is made to solve the aforementioned technical problems. Its purpose is to provide an external noise reproduction system that can create a realistic external sound field environment in a ground test laboratory, simulating the external noise during the high-speed operation of aircraft, high-speed trains, buses, etc., for design and development personnel to conduct sound insulation performance tests on wall panels, and can also facilitate maintenance personnel to locate faults in the wall panel structure.

[0009] To achieve the above objectives, the present invention provides an external noise reproduction system, characterized by comprising: an equidistant measurement and control surface construction system, which can perform three-dimensional spatial scanning of the object under test, identify its surface morphology, and establish an equidistant curved surface model that closely approximates the surface morphology of the object under test to form an equidistant measurement and control surface; an array-type sound source system, which emits white noise excitation and has multiple speaker units; a curved microphone array, which consists of multiple microphones and can surround the object under test to collect and monitor noise signals; and a control system, which consists of a control computer, a sound card, a microphone amplifier, a power amplifier, and control software and algorithms, and is communicatively connected to the array-type sound source system and the curved microphone array respectively to obtain excitation response and control the array-type sound source system and the curved microphone array.

[0010] Preferably, the array-type sound source system is a matrix speaker array, consisting of M×L speaker units, with the base of each speaker unit connected to an independent micro hydraulic cylinder.

[0011] Preferably, the plurality of microphones are evenly arranged on the outer surfaces of the different geometric shapes of the object being measured.

[0012] Preferably, the array-type sound source system and the curved microphone array are mounted on the same automated guided vehicle.

[0013] Preferably, the control system calculates the transfer function between the array-type sound source system and the curved microphone array, and uses the simulated target sound spectrum and the transfer function to calculate the initial drive spectrum of the external noise reproduction system, which serves as the initial drive signal for the multiple speaker units in the simulated sound field. During the playback of the initial drive spectrum, the microphone amplifier of the control system receives the noise signal collected by the curved microphone array as feedback from the external noise reproduction system and compares it with the sound information of the simulated sound field. The control computer of the control system uses the feedback signal to iteratively adjust and correct the initial drive spectrum N times until the error between the Nth generation drive spectrum after N iterations and the target sound spectrum to be simulated is less than a specified value, and saves the Nth generation drive spectrum as a stable drive spectrum.

[0014] More preferably, the external noise reproduction system can be applied to airplanes, high-speed trains, and buses.

[0015] Based on the above configuration, the system constructed using the equidistant measurement and control surface can perform three-dimensional spatial scanning of the object under test, identify its surface morphology, establish equidistant measurement and control surfaces that are close to the surface morphology of the object under test, and locate them through speaker units, thereby improving the ability to construct irregular curved surface sound fields using array-type sound source systems.

[0016] Furthermore, since the array-type sound source system can be moved according to the needs of the scene, it can simulate the surface sound field at various positions outside the object under test. The height, pitch angle, curvature and matrix directivity can be adjusted according to the geometric characteristics of the outer surface of the test object. The miniature hydraulic cylinder equipped with the speaker unit can independently adjust the position of the individual speaker unit so that the envelope formed by each speaker unit is consistent with the equally spaced measurement and control surface. This makes the array-type sound source system suitable for sound field simulation of different geometric shapes. It can be used in aircraft, high-speed rail, buses, etc. It can not only be used by design and R&D personnel to conduct sound insulation performance tests of wall panels, but also by maintenance personnel of airlines and other companies for wall panel structure fault location work.

[0017] Furthermore, the curved microphone array can surround the object under test and be arranged in a matrix on the outer curved surface of the object under test. The resulting curved surface almost coincides with the outer surface of the object under test, thereby enabling more accurate acquisition of the external curved surface noise field when the object under test is working.

[0018] Furthermore, the curved microphone array can also collect the curved noise field of the surface of the object under test when the array-type sound source system emits sound, and feed it back to the control system. It can then perform error analysis with the target sound field that needs to be reproduced, and adjust the driving spectrum of the array-type sound source system to form a closed-loop control system, thereby achieving accurate simulation of the external sound field of the object under test.

[0019] In particular, the controller can achieve independent control of each speaker unit in the array-type sound source system. The system has a better ability to simulate sound fields with large sound pressure level gradients. It is especially suitable for simulating the turbulent boundary layer sound field formed by irregular surfaces of vehicles in high-speed flow fields. It can realize the simulation of the external sound field of vehicles such as airplanes and high-speed trains when they are running at high speeds. It can be used by design and R&D personnel to conduct sound insulation performance testing of wall panels. It can also be used by maintenance personnel of airlines or railway departments to carry out wall panel structure fault location work based on the abnormal performance of the sound field inside the cabin.

[0020] This invention can not only simulate steady-state sound sources on irregular curved surfaces, but also realize dynamic sound load control of irregular curved surfaces in the time domain through a matrix sound source system. It can simulate sound sources on the outer surface of irregular curved surfaces under changing working conditions and be used to evaluate the internal noise comfort of the tested object.

[0021] Therefore, the cabin noise reproduction system of the present invention can provide a reliable test platform for the sound insulation research of the wall panels of transportation vehicles such as airplanes, high-speed trains, and buses. It can also be used by maintenance personnel of airlines, railway departments, and automobile 4S shops to carry out wall panel structure fault location work, which plays an important role in improving the overall environment and comfort inside transportation vehicles. Attached Figure Description

[0022] Figure 1 (a) and (b) are schematic diagrams illustrating the application of the external noise reproduction system of the present invention in a civil aircraft as an embodiment, wherein... Figure 1 (a) shows a schematic cross-sectional view of a civil aircraft, for example, in the YZ direction. Figure 1 (b) shows a schematic cross-sectional view of a civil aircraft, for example, in the XY direction.

[0023] Figure 2 yes Figure 1 The diagram shows a micro hydraulic cylinder connected to the speaker unit constituting the array-type sound source system in the external noise reproduction system of the present invention.

[0024] Figure 3 yes Figure 1 The diagram shown is a control logic diagram of the control system for controlling the array-type sound source system and the curved microphone array in the external noise reproduction system of the present invention.

[0025] Figure 4 It is to utilize Figure 1 The flowchart shown is for a sound insulation test of the external noise reproduction system of the present invention.

[0026] (Symbol Explanation)

[0027] 100. External noise reproduction system;

[0028] 110 Array-type sound source system;

[0029] 111 speaker units;

[0030] 112. Base;

[0031] 113 Miniature hydraulic cylinder;

[0032] 120 curved microphone array;

[0033] 121 Microphone;

[0034] 130 Control System;

[0035] 200 Automated Guided Vehicles. Detailed Implementation

[0036] The external noise reproduction system 100 of the present invention will now be described with reference to the accompanying drawings, wherein... Figure 1 (a) and (b) are schematic cross-sectional views in the YZ and XY directions, respectively, of the external noise reproduction system 100 of the present invention applied in a civil aircraft as an embodiment. Figure 2 yes Figure 1 The diagram shown illustrates the structure of the miniature hydraulic cylinder 113 connected to the speaker unit 111 constituting the array-type sound source system 110 in the compartment external noise reproduction system 100 of the present invention. Figure 3 yes Figure 1 The control logic diagram shown is for the control system 130 that controls the array-type sound source system 110 and the curved microphone array 120 in the compartment external noise reproduction system 100 of the present invention.

[0037] Furthermore, in the description of the present invention, for example, it is applied to... Figure 1 The following is an example of a civil aircraft (the object under test) for illustration. However, the application scenarios or objects under test of the external noise reproduction system 100 of the present invention are not limited to civil aircraft. They can also be transportation vehicles that can operate at high speeds, such as trains (including high-speed rail), subways, light rail, and buses.

[0038] like Figure 1As shown in (a) and (b), the external noise reproduction system 100 of the present invention includes: an equidistant measurement and control surface construction system (not shown), which can perform three-dimensional spatial scanning of the object under test (e.g., aircraft 1, high-speed rail, bus, etc.), identify its surface morphology, and establish an equidistant curved surface model that is close to the surface morphology of the object under test to form an equidistant measurement and control surface; an array-type sound source system 110, which is a matrix loudspeaker array composed of M×L loudspeaker units 111; and a curved microphone array 120. The system 120 surrounds the object under test and consists of multiple microphones 121, which are evenly arranged on the outer surface of the object under test (e.g., the outer surface of different geometric shapes of an airplane, high-speed train, bus, etc.) to collect and monitor the acoustic load control target of the outer surface of the object under test (e.g., an irregular surface); and the system 130 is communicatively connected to the array-type sound source system 110 and the curved microphone array 120, respectively, and consists of a control computer, a sound card, a microphone amplifier, a power amplifier, and control software and algorithms.

[0039] like Figure 1 As shown in (b), the array-type sound source system 110 and the curved microphone array 120 are mounted on the same automated guided vehicle 200. When the curved microphone array 120 tests around the object under test, it can obtain the overall outer surface sound field of the object under test (e.g., airplane 1, high-speed rail, bus, etc.). When the array-type sound source system 110 emits sound, the curved microphone array 120 can monitor the simulated sound field.

[0040] The control logic of control system 130 is as follows Figure 3As shown, in block A110, the array-type sound source system 110 emits white noise excitation, while in block A120, the curved microphone array 120 acquires the excitation signal. The control system 130 obtains the excitation response in block A130, calculates the transfer function between the array-type sound source system 110 (sound source) and the curved microphone array 120 (microphone 121) in block A140, and obtains the initial drive signal of M×L loudspeaker units 111 in the simulated sound field as needed, for example, using the MIMO method in block A150. That is, the initial drive spectrum of the external noise reproduction system 100 is calculated using the simulated target sound spectrum and transfer function. In the subsequent process of playing the initial drive signal (initial drive spectrum) of M×L loudspeaker units 111 in block A210_1, the microphone amplifier in block A220_1 receives the noise signal collected by the curved microphone array 120 as feedback to the external noise reproduction system 100 and compares it with the acoustic information of the simulated sound field. In block A230_1, the control computer uses the feedback signal to adjust and correct the aforementioned initial drive spectrum. In block A240_1, a new drive signal (first-generation drive signal) is generated. After several iterations (e.g., n times), the Nth-generation drive signal of M×L loudspeaker units 111 is played in block A210_n+1. In block A220_n+1, the error between the Nth-generation drive signal and the target sound spectrum (target sound field) to be simulated meets the requirements. At this time, the Nth-generation drive signal is saved as a stable drive spectrum, thereby realizing the simulation of external noise and providing an excitation environment for the sound insulation test of the wall panel.

[0041] Furthermore, the height, pitch angle, matrix surface radian, and matrix directivity of the array-type sound source system 110 are all adjustable, such as... Figure 2 As shown, the base 112 of each speaker unit 111 is connected to an independent miniature hydraulic cylinder 113. The array-type sound source system 110 can activate the action of each miniature hydraulic cylinder 113 according to the equally spaced measuring and control surface to adjust the position of the speaker unit 111 so that the speaker unit 111 forms an envelope surface that coincides with the equally spaced measuring and control surface.

[0042] The external noise reproduction system 100 of the present invention can adapt to the test object with different geometric shapes, and the array-type sound source system 110 can simulate the external sound sources of different means of transportation such as airplanes, high-speed trains, and buses. The array-type sound source system 110 can reproduce a 120dB noise zone within the area of ​​interest, with the sound pressure level in the core area reaching up to 125dB. In addition, the channels of the multiple speaker units 111 are independently controlled by the control system 130, giving the external noise reproduction system 100 a strong ability to simulate large gradient sound fields on irregular surfaces.

[0043] In addition, it can also be like Figure 4As shown, the cabin noise reproduction system 100 of the present invention is used to conduct sound insulation tests on the wall panels of the tested object or to locate wall panel sound leakage faults.

[0044] Specifically, in step S100, the height, pitch angle, matrix surface curvature, and matrix directivity of the array-type sound source system 110 in the external noise reproduction system 100 are adjusted according to the surface geometry of the object under test (e.g., aircraft 1, high-speed train, bus, etc.) so that it is approximately parallel to the surface of the object under test (e.g., aircraft 1, high-speed train, bus, etc.).

[0045] Next, in step S200, the equal-spacing measurement and control surface construction system is activated to identify the geometry of the surface area of ​​the object being measured. As needed, a virtual equal-spacing measurement and control surface is constructed at a distance from the surface being measured to accurately depict the optimal sound emission position of the speaker unit 111 of the array sound source system 110.

[0046] Subsequently, in step S300, according to the constructed equidistant measuring and control surface, the control system 130 controls the micro hydraulic cylinder 113 corresponding to each speaker unit 111 to act so that the envelope of the array sound source system 110 coincides with the equidistant measuring and control surface. At this time, in step S400, the curved microphone array 120 is arranged on the surface of the object being measured.

[0047] After the array-type sound source system 110 and the curved microphone array 120 are arranged, in step S500, the multiple speaker units 111 of the array-type sound source system 110 sequentially emit broadband white noise, while the curved microphone array 120 collects sound signals, and the control system 130 calculates the transfer function matrix of the array-type sound source system 110 and the curved microphone array 120.

[0048] Next, in step S600, the control system 130 reads the target sound field noise spectrum signal to be simulated, and calculates the driving signal of the array-type sound source system as the initial driving spectrum based on the transfer function matrix obtained in step S500. Subsequently, in step S700, the array-type sound source system 110 plays the initial driving spectrum obtained in step S600, and the curved microphone array 120 detects the noise signal as the simulated sound field and feeds it back to the control system 130 to calculate the error between the simulated sound field and the target sound field. The control system repeatedly adjusts the driving spectrum according to the error until the error meets the requirements, thereby obtaining a stable driving spectrum.

[0049] Finally, in step S800, the array-type sound source system 110 plays the stable driving spectrum obtained in step S700 to form a stable simulated sound field on the outer surface of the wall panel. Transmitted sound is detected on the other side of the wall panel, which can calculate the sound insulation performance of the wall panel, or compare the sound insulation effect of the wall panel before and after replacing the wall panel structure, or locate the weak points of the sound insulation layer according to the sound field environment inside the cabin, or locate and repair faults such as sound leakage in the wall panel.

[0050] Other advantages and modifications will readily occur to those skilled in the art. Therefore, more broadly, the invention is not limited to the specific details and representative embodiments shown and described herein. Thus, modifications can be made without departing from the spirit or scope of the overall inventive concept as defined by the appended claims and their equivalents.

Claims

1. An external noise reproduction system, characterized in that, include: An equidistant measurement and control surface construction system is provided, which can perform three-dimensional spatial scanning on the object under test, identify its surface morphology, and establish an equidistant curved surface model that is close to the surface morphology of the object under test to form an equidistant measurement and control surface. An array-type sound source system (110) is a matrix loudspeaker array that emits white noise excitation. It consists of M×L loudspeaker units (111). The base (112) of each loudspeaker unit (111) is connected to an independent micro hydraulic cylinder (113). The array-type sound source system (110) can activate the action of each micro hydraulic cylinder (113) according to the equidistant measuring and control surface to adjust the position of the loudspeaker unit (111) so that the loudspeaker unit (111) forms an envelope surface that coincides with the equidistant measuring and control surface. A curved microphone array (120), comprising multiple microphones (121), is provided to surround the object under test for acquiring and monitoring noise signals; and The control system (130) consists of a control computer, a sound card, a microphone amplifier, a power amplifier, and control software and algorithms. It is communicatively connected to the array-type sound source system (110) and the curved microphone array (120) to obtain excitation response and control the array-type sound source system (110) and the curved microphone array (120).

2. The external noise reproduction system as described in claim 1, characterized in that, Multiple microphones (121) are evenly arranged on the outer surfaces of the different geometric shapes of the object being measured.

3. The external noise reproduction system as described in claim 1, characterized in that, The array-type sound source system (110) and the curved microphone array (120) are mounted on the same automated guided vehicle (200).

4. The external noise reproduction system as described in claim 1, characterized in that, The control system (130) calculates the transfer function between the array-type sound source system (110) and the curved microphone array (120), and uses the simulated target sound spectrum and the transfer function to calculate the initial drive spectrum of the external noise reproduction system, which serves as the initial drive signal for the plurality of loudspeaker units (111) in the simulated sound field. During the playback of the initial drive spectrum, the microphone amplifier of the control system (130) receives the noise signal collected by the curved microphone array (120) as feedback from the external noise reproduction system and compares it with the acoustic information of the simulated sound field. The control computer of the control system (130) uses feedback signals to iteratively adjust and correct the initial driving spectrum N times until the error between the Nth generation driving spectrum after N iterations and the target sound spectrum to be simulated is less than a specified value, and saves the Nth generation driving spectrum as a stable driving spectrum.

5. The external noise reproduction system as described in any one of claims 1 to 4, characterized in that, The external noise reproduction system (100) can be applied to airplanes, high-speed trains, and buses.

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