Loudspeaker acoustic load test system

Abstract

The application discloses a loudspeaker acoustic load test system, and relates to the technical field of loudspeaker acoustic load test systems. a : wherein, A s represents a radiation area, R e represents a voice coil DC resistance, L e represents a voice coil inductance, Bl represents a magnetic circuit force factor, R ms represents a mechanical damping, M ms represents a mechanical vibration mass, C ms represents a mechanical compliance. The application is based on a classical electroacoustic system, utilizes a sound impedance calculation relationship of a loudspeaker small signal model, and proposes a sound impedance test system based on loudspeaker T / S parameters. Compared with a traditional sound wave guide method for measuring sound impedance, the application has the advantages of high signal-to-noise ratio, low cost, strong adaptability, high efficiency and convenience, and can be used for parameter measurement and quality control in laboratory research and development and production line batch manufacturing.

Description

Technical Field

[0001] This invention relates to a loudspeaker acoustic load ("acoustic load", also known as "acoustic impedance") testing system. Background Technology

[0002] Acoustic impedance is an important concept in the study of acoustic radiation and transmission. It is generally defined as sound pressure divided by volume velocity. However, in practice, it is difficult to directly and accurately measure volume velocity. Therefore, current main methods for measuring acoustic impedance are based on waveguide systems that measure parameters related to incident and reflected waves, primarily using standing wave ratio (VSWR) and transfer function methods. However, due to limitations in sample size and operating bandwidth of the waveguide itself, existing acoustic impedance measurement methods have significant limitations in practical applications, mainly in the following aspects:

[0003] (1) It limits the cross-sectional shape of the sample, and the cross-sectional dimensions must be strictly the same as the internal dimensions of the tube;

[0004] (2) Narrow measurement bandwidth: The measurement bandwidth is limited by the tube size and microphone arrangement, and can only provide a limited test range;

[0005] (3) Direct acquisition of acoustic signals results in a signal-to-noise ratio that is greatly affected by the surrounding environment;

[0006] (4) The multi-microphone design and multi-channel signal acquisition card configuration are expensive.

[0007] Speaker enclosure systems are an important form of speaker application. Due to the design evaluation requirements during the R&D phase and the need for material and assembly process control during subsequent production, measuring the acoustic load impedance of speaker systems is crucial data. Typically, automotive speaker enclosures are constructed from injection-molded parts, metal parts, and foam mesh, exhibiting diverse acoustic system materials and irregular shapes. Because of the complexity and diversity of automotive acoustic system enclosures, conventional acoustic impedance tube systems often cannot directly measure the corresponding load acoustic impedance. Furthermore, considering the control of product assembly processes in actual production, the high background noise of production line environments, and production cost considerations, a new, cost-effective, and high signal-to-noise ratio acoustic impedance testing solution is urgently needed. Summary of the Invention

[0008] The technical problem to be solved by this invention is that, due to the design evaluation in the R&D stage and the need for control of materials and assembly processes in the subsequent production stage, the measurement of acoustic load impedance of loudspeaker systems is an important data point. However, for complex vehicle speaker enclosures, due to the variety of acoustic system materials and irregular shape of the enclosure, conventional acoustic impedance tube systems often cannot directly measure the corresponding load acoustic impedance.

[0009] To solve the above-mentioned technical problems, the technical solution of the present invention is to provide a loudspeaker acoustic load testing system, wherein the loudspeaker under test is connected to a transducer, characterized in that the loudspeaker acoustic load testing system includes a control host, a dynamic signal acquisition card, a current sensor, and a voltage sensor, wherein:

[0010] Current and voltage sensors record the current and voltage signals between the transducer terminals, respectively.

[0011] After the control host obtains the current and voltage signals through the dynamic signal acquisition card, it measures the electrical terminal impedance Z in real time. e The acoustic impedance Z is calculated using the following formula. a :

[0012]

[0013] In the formula, A s Indicates the radiation area, R e Indicates the DC resistance of the voice coil, L e B represents the voice coil inductance, Bl represents the magnetic force factor, and R represents the magnetic force factor. ms Indicates mechanical damping, M ms Represents mechanical vibration mass, C ms Indicates mechanical compliance.

[0014] Based on classical electroacoustic systems, this invention utilizes the acoustic impedance calculation relationship of the loudspeaker small-signal model to propose an acoustic impedance testing system based on the loudspeaker T / S parameter. Compared with traditional acoustic waveguide measurement methods, this invention has the advantages of high signal-to-noise ratio, low cost, strong adaptability, high efficiency and convenience, and can be used for parameter measurement and quality control in laboratory research and development and mass production lines. Attached Figure Description

[0015] Figure 1 The lumped parameter model of the loudspeaker system is illustrated;

[0016] Figure 2 This is a schematic diagram of signal transmission in the test system;

[0017] Figure 3 This is a schematic diagram of the hardware connections for the test system. Detailed Implementation

[0018] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0019] like Figure 1 The lumped parameter model of the loudspeaker system shown can quickly and effectively solve acoustic problems encountered in practice under the long-wavelength approximation. For the loudspeaker system itself, this invention commonly uses T / S parameter modeling. This embodiment selects a certain type of vehicle-mounted loudspeaker enclosure system as the research object. First, the Klippel RD testing system is used, and a laser displacement sensor is employed to measure the small-signal parameters of the loudspeaker unit. The measured parameters of the loudspeaker unit are shown in Table 1 below:

[0020] symbol Physical meaning Bl Magnetic circuit force factor <![CDATA[R e ]]> Voice coil DC resistance <![CDATA[L e ]]> Voice coil inductor <![CDATA[M ms ]]> Mechanical vibration mass <![CDATA[R ms ]]> Mechanical damping <![CDATA[C ms ]]> mechanical compliance <![CDATA[f s ]]> Resonance frequency <![CDATA[A s ]]> Radiation area

[0021] Table 1 Basic Parameter Definitions

[0022] Based on the basic parameters shown in Table 1, Z is further defined. e For electrical terminal impedance, Z m For mechanical end impedance, Z a "This is the acoustic impedance". Using the transformation relationship of the lumped parameters in the lumped parameter model, the electrical impedance Z can be obtained as shown in formula (1). e With mechanical end impedance Z m relation:

[0023]

[0024] Similarly, the mechanical end impedance Z can be obtained. m Acoustic impedance Z a The relationship is shown in formulas (2) and (3):

[0025]

[0026]

[0027] In formula (3), Z m-a This represents the acoustic impedance mapped to the mechanical part. Combining equations (1) to (3), we can obtain the acoustic impedance, as shown in equation (4):

[0028]

[0029] In this way, based on the known small-signal parameters of the loudspeaker unit, the numerical relationship of the acoustic impedance at the acoustic end of the system was established.

[0030] Combination Figure 2 and Figure 3The loudspeaker acoustic load testing system disclosed in this embodiment includes four parts: a control host, a dynamic signal acquisition card, a current sensor, and a voltage sensor. The current sensor and voltage sensor record the current and voltage signals between the transducer terminals, respectively. After acquiring the current and voltage signals, the dynamic signal acquisition card communicates with the control host to obtain the electrical impedance curve, i.e., the electrical terminal impedance Z. e .

[0031] The small-signal parameters of the transducer used need to be obtained in advance. Then, by using the physical quantity relationship established by formula (4) and substituting the electrical impedance obtained from actual measurement, the acoustic impedance Z can be calculated. a .

Claims

1. A loudspeaker acoustic load test system, a loudspeaker under test connected to a transducer, characterized by, The loudspeaker acoustic load test system comprises a control host, a dynamic signal acquisition card, a current sensor and a voltage sensor, wherein: The current sensor and the voltage sensor record the current signal and the voltage signal between the transducer terminals, respectively; The control host obtains the current signal and the voltage signal through a dynamic signal acquisition card, and obtains the electrical terminal impedance Z in real time e , and calculates the acoustic terminal impedance Z by using the following formula a : where A s represents the radiating area, R e represents the voice coil DC resistance, L e represents the voice coil inductance, Bl represents the magnetic circuit force factor, R ms represents the mechanical resistance, M ms represents the mechanical vibration mass, C ms represents the mechanical compliance.

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