Straight-flow type double-channel noise reduction wind tunnel

Abstract

The invention relates to the field of aerodynamic experimental equipment, and particularly discloses a straight-flow type double-channel silencing wind tunnel which comprises an air duct system, a power system, a double-channel diffusion section, a silencing chamber, a silencing flow guide block, a control system and the like. Wherein the anechoic chamber and the experiment section are combined into a whole, and the inner wall surface of the anechoic chamber is filled with the anechoic wedges, so that noise generated in the experiment process can be effectively absorbed; the double-channel diffusion section adopts a bent pipe design and is attached with a silencing material, so that noise transmission of the motor can be inhibited; the silencing flow guide block structure adopts a streamline design to guide air flow to be distributed stably, and turbulent flow and energy loss are reduced. By optimizing the structural design and material application, the noise level during wind tunnel operation is remarkably reduced, the flow velocity, uniformity and stability of airflow are improved, and the accuracy and reliability of experiments are improved. In addition, the device is further provided with an efficient power system and a control system, can meet the flow field speed requirements under different experiment conditions, and has good application prospects and economical efficiency.

Description

Technical Field

[0001] The present invention relates to the field of aerodynamic experimental equipment, and particularly to a direct-current dual-channel silencing wind tunnel. Background Art

[0002] A wind tunnel is an experimental device that artificially generates and controls airflows, and is widely used in aerodynamic research and tests to simulate the airflow around an aircraft or an object. Traditional wind tunnels have played an important role in aerodynamic research, but there are some technical defects and deficiencies during operation, especially in terms of noise control.

[0003] In the prior art, when the motor of a traditional wind tunnel operates, it will generate significant noise, which will directly spread to the experimental area and affect the accuracy of acoustic experiment results. In addition, the structural design of traditional wind tunnels cannot effectively isolate the intrusion of external noise into the internal area, and the flow noise generated in the experimental area will be reflected by the pipe wall and further interfere with the accuracy of acoustic experiments. Although some design schemes of silencing wind tunnels have emerged in recent years, such as installing silencers in the air inlet pipe of the fan, these existing technologies still have limitations and cannot fully meet the noise reduction requirements of aeroacoustic experiments.

[0004] In addition, there are deficiencies in the airflow distribution and control of traditional wind tunnels, resulting in difficulties in achieving an ideal state of flow field velocity and uniformity. For example, in a wind tunnel with a single-channel design, the airflow velocity is high when flowing out, which is likely to generate turbulence and eddy currents, not only increasing energy loss but also possibly causing additional aerodynamic noise. These problems limit the application of wind tunnels in high-precision aeroacoustic experiments.

[0005] Therefore, the present invention aims to solve the noise problems and airflow distribution control problems of wind tunnels in the prior art, and proposes a direct-current dual-channel silencing wind tunnel device. By optimizing the structural design and the selection of sound-absorbing materials, the noise propagation is effectively reduced, and the flow velocity, uniformity, and stability of the airflow are improved, thereby enhancing the performance and application value of the wind tunnel in aeroacoustic experiments. Summary of the Invention

[0006] The purpose of the present invention is to provide a direct-current dual-channel silencing wind tunnel to solve the noise problems and airflow distribution control problems of wind tunnels in the prior art.

[0007] To achieve the above purpose, the present invention provides the following solution: A direct-current dual-channel silencing wind tunnel, comprising:

[0008] A soundproof chamber, the inner wall of which is lined with sound-absorbing wedges;

[0009] Air duct system, the air duct system includes an air inlet, a stabilization section, a contraction section, an experimental section, a double-channel air duct section and two diffuser sections connected in sequence; the experimental section is arranged in a soundproof room, the double-channel air duct section has an air duct inlet and two air duct outlets, the two air duct outlets are symmetrically distributed on both sides of the air duct inlet and form a 90° angle with the air duct inlet; the two diffuser sections are respectively connected to the two air duct outlets;

[0010] Power system, the power system includes an axial flow fan installed in the diffuser section and a servo motor connected to the axial flow fan;

[0011] Control system, the control system includes a control unit and a computer connected to the servo motor.

[0012] Optionally, the diffuser section includes a first diffuser section, a second diffuser section and an air outlet; the first diffuser section is connected to the double-channel air duct section, and is used to reduce the air flow velocity and increase the static pressure; the second diffuser section is used to further reduce the air flow velocity and direct the air flow out of the wind tunnel.

[0013] Optionally, a sound-absorbing and flow-guiding block is arranged at the bifurcation of the double-channel air duct section.

[0014] Optionally, the sound-absorbing and flow-guiding block has a streamlined flow-guiding surface, and its material is the same as that of the sound-absorbing wedge.

[0015] Optionally, the sound-absorbing wedge is composed of a base and a wedge part, the length of the base is 10 cm, and the length of the wedge part is 30 cm.

[0016] Optionally, the sound-absorbing wedges are arranged in a criss-cross pattern.

[0017] Optionally, the material of the sound-absorbing wedge is one or several of glass wool, rock wool, and polyester fiber.

[0018] Optionally, the air flow velocity range in the experimental section is 0.1 - 60 m / s, the flow velocity stability coefficient ≤ 0.5%, the flow velocity uniformity coefficient ≤ 1%, and the wind speed resolution is 0.1 m / s.

[0019] Optionally, a flow velocity sensor is arranged in the experimental section, and the flow velocity sensor is connected to the computer through the control unit in a signal manner.

[0020] Optionally, the direct-current double-channel soundproof wind tunnel further includes a high-definition camera and a microphone arranged in the soundproof room, and the high-definition camera and the microphone are connected to the computer.

[0021] Compared with the prior art, the present invention discloses at least the following beneficial effects:

[0022] Through innovative structural design and material application, the present invention achieves remarkable noise reduction effects and optimized air flow distribution. Specifically, by adding a soundproof chamber and sound-absorbing wedges in the wind tunnel, fluid noise generated in the experimental area is effectively absorbed, reducing noise reflection and propagation. At the same time, the design of the dual-channel diffuser section and the attachment of sound-absorbing materials to the duct wall further suppress the propagation of motor noise to the experimental area, significantly reducing the noise level in the experimental area and meeting the requirements of low-noise environments for aeroacoustic experiments. In addition, the sound-absorbing and flow-guiding blocks in the middle section of the dual-channel adopt a streamlined design, which can effectively guide the air flow, reduce the direct impact of the air flow on the inner wall, reduce energy loss, and at the same time reduce the generation of aeroacoustic noise, improving the uniformity and stability of the air flow. These improvements not only optimize the air flow distribution of the wind tunnel, but also improve the accuracy and reliability of experimental data, providing a more ideal experimental environment for aeroacoustic research. At the same time, the present invention optimizes the structure on the basis of the traditional wind tunnel, improves the overall performance and efficiency of the system, reduces the operating cost, and has good economic performance and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0024] Figure 1 It is a schematic structural diagram of the direct-current dual-channel soundproof wind tunnel of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the sound-absorbing wedge of the present invention;

[0026] Figure 3 It is a schematic internal structure diagram of the dual-channel air duct section of the present invention;

[0027] Figure 4 It is a schematic structural diagram of the sound-absorbing and flow-guiding block of the present invention;

[0028] Figure 5 It is a schematic system connection diagram of the direct-current dual-channel soundproof wind tunnel of the present invention in the experimental operation state;

[0029] Figure 6 It is a control schematic diagram of the direct-current dual-channel soundproof wind tunnel of the present invention.

[0030] In the figure: 1, air inlet; 2, stabilization section; 3, contraction section; 4, sound insulation chamber; 5, double-channel air duct section; 6, diffuser section; 7, first diffuser section; 8, second diffuser section; 9, air outlet; 10, sound insulation and flow guiding block; 11, flow velocity sensor; 12, high-definition camera; 13, experimental model; 14, microphone; 15, servo motor; 16, control unit; 17, computer. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0033] Referring to Figures 1 to 6 As shown, the embodiment of the present invention provides a direct-current double-channel sound insulation wind tunnel, which includes an air duct system, a power system, a sound insulation chamber 4, a control system, and a supporting system.

[0034] As Figure 1 shown, the air duct system includes an air inlet 1, a stabilization section 2, a contraction section 3, an experimental section, a double-channel air duct section 5, and two diffuser sections 6 that are connected in sequence. Among them, the experimental section is arranged in the sound insulation chamber 4 and is integrated with the sound insulation chamber 4. The air inlet 1, the stabilization section 2, and the contraction section 3 are located at the air inlet end of the sound insulation chamber 4, and the double-channel air duct section 5 and the two diffuser sections 6 are located at the air outlet end of the sound insulation chamber 4. The double-channel air duct section 5 has one air duct inlet and two air duct outlets, and adopts a T-shaped shunt structure, specifically as Figure 3 shown. The air duct inlet of the double-channel air duct is located in the middle and is connected to the experimental section. The two air duct outlets extend to both sides at 90° to the air duct inlet respectively, forming a shunt, that is, the two air duct outlets are symmetrically distributed on both sides of the air duct inlet and form a 90° angle with the air duct inlet. Both air duct outlets are connected to the diffuser section 6, and the diffuser section 6 is composed of a first diffuser section 7, a second diffuser section 8, and an air outlet 9. In this embodiment, by adding a sound insulation chamber 4 in the experimental section and setting a diffuser section 6 with a double-channel elbow structure at the rear end of the experimental section, a better experimental application effect is achieved.

[0035] In this embodiment, the experimental section is located between the contraction section 3 and the double-channel air duct section 5. The experimental section is used to place the experimental model 13 for conducting research on various aspects such as aerodynamic characteristics and boundary layer characteristics. The air flow velocity range in the experimental section of the present invention is 0.1 - 60 m / s, the flow velocity stability coefficient ≤ 0.5%, the flow velocity uniformity coefficient ≤ 1%, and the wind speed resolution is 0.1 m / s.

[0036] In a specific embodiment, the overall dimensions of the experimental section in this embodiment are 2.0 m in length, 2.4 m in width, and 2.4 m in height. According to the dimensions of the experimental section, an appropriate experimental model 13 is placed.

[0037] In this embodiment, the anechoic chamber 4 is integrated with the experimental section, that is, the inside of the anechoic chamber 4 is the experimental area. Therefore, the dimensions of the anechoic chamber 4 are the same as those of the experimental section, both being 2.0 m in length, 2.4 m in width, and 2.4 m in height. Windows are respectively opened on the left and right sides of the anechoic chamber 4. The windows are all square and are located in the middle. The size of the left window of the anechoic chamber 4 is the same as the outlet of the contraction section 3, and the size of the right window is the same as the inlet of the double-channel air duct section 5, that is, the anechoic chamber 4 is connected to the contraction section 3 on the left and the double-channel air duct section 5 on the right, and it is connected on both sides.

[0038] In a specific embodiment, the inner wall of the anechoic chamber 4 is filled with anechoic wedges, and the structure of the anechoic wedges is as Figure 2 shown. The adjacent anechoic wedges are arranged in a criss-cross pattern, so as to ensure that the noise generated by the experiment is fully absorbed and eliminated. The anechoic wedges utilize the principle of gradual transition to make the acoustic impedance of the material match the acoustic impedance of the air, so that the sound wave can smoothly enter the sound absorber and be efficiently absorbed.

[0039] The anechoic chamber 4 is built outside the experimental section, that is, the experimental section is wrapped inside. The fluid noise generated when the air flow passes through the experimental model 13 is absorbed by the anechoic wedges, reducing the reflection and propagation of the flow noise, and thus improving the accuracy and reliability of the experimental data.

[0040] As Figure 2 shown, the anechoic wedge consists of a base and a wedge part. The base is the part with a constant bottom cross-section, and the wedge part is the part with a gradually increasing cross-section starting from the tip. The sound absorption performance of the anechoic wedge is related to the wedge length, material properties, and the depth of the cavity behind. The longer the wedge, the better the low-frequency sound absorption performance. In the design of the anechoic chamber, the lowest frequency with an absorption coefficient of 0.99 is usually called the cut-off frequency of the anechoic wedge. Usually, the relationship between the cut-off frequency and the wedge length can be calculated by the following formula:

[0041]

[0042] In the formula, L represents the length of the anechoic wedge; D represents the depth of the cavity between the bottom of the wedge and the rigid surface; Fc represents the cut-off frequency.

[0043] Through calculation, the dimensions of the sound-absorbing wedge required for the present invention are L = 40 cm, L1 = 30 cm, L2 = 10 cm, and D = 0. At this time, the noise reduction effect can reach the best and meet the requirements of acoustic experiments.

[0044] Therefore, in a specific embodiment, the base length L2 of the sound-absorbing wedge is 10 cm, the wedge length L1 is 30 cm, the total length L is 40 cm, and the depth D of the inner wall cavity of the base and the anechoic chamber 4 is 0.

[0045] In a specific embodiment, the sound-absorbing wedge is made of polyester fiber.

[0046] In this embodiment, by adding the anechoic chamber 4 and the sound-absorbing wedge, the wind tunnel can be applied to the experimental research of aeroacoustics. On the basis of the functions of the traditional wind tunnel, the structure of the diffuser section 6 is further optimized to become a double-channel elbow, and sound-absorbing materials that can reduce noise are attached to the wall of the pipe, reducing the noise decibel value of the equipment noise transmitted to the wind tunnel experimental area.

[0047] In this embodiment, the internal structure of the double-channel air duct section 5 is as Figure 3 shown. The air duct inlet of the double-channel air duct section 5 is connected to the right window of the anechoic chamber 4, and the two air duct inlets are connected to the diffuser section 6 of the same specification and size. The purpose of designing the double-channel air duct section 5 as an elbow is to suppress the direct transmission of motor noise to the experimental area, and the sound-absorbing material attached to the pipe wall can enhance the sound absorption effect. After actual measurement, except for the low-frequency noise (200 Hz and below) that is difficult to effectively eliminate, the overall absorption effect of the noise in other frequency bands (medium and high frequencies above 200 Hz) is good, and the actual noise is reduced by 20 - 30 dB.

[0048] Furthermore, a flow splitting structure, that is, the sound-absorbing and guiding block 10, is added in the middle section of the double-channel air duct section 5 to split the airflow from the laboratory, avoiding the heavy impact of the high-speed airflow on the inner wall, reducing the turbulence and eddy current of the airflow, and making the airflow flow out more smoothly, thereby reducing the energy loss. Specifically, inside the double-channel air duct section 5, a sound-absorbing and guiding block 10 with the same height as the double-channel air duct section 5 is provided at the bifurcation. The sound-absorbing and guiding block 10 adopts a streamlined design. Specifically, the sound-absorbing and guiding block 10 has a streamlined guiding surface, as Figure 4As shown in the figure. The sound-absorbing and flow-guiding block 10 utilizes the principle of fluid mechanics to ensure that the air flow can flow smoothly in the double-channel air duct section 5, reduce the frictional resistance of the air flow in the double-channel air duct section 5, effectively improve the flow efficiency of the air flow, and avoid the energy loss of the air flow caused by the direct impact of the high-speed air flow on the inner wall face to face. The air flow flows out from the experimental section and enters the double-channel air duct section 5. After the air flow in the front section is calmed and stabilized, due to the existence of the sound-absorbing and flow-guiding block 10 at the bifurcation, the air flow is divided into two parts in the middle of the sound-absorbing and flow-guiding block 10 and flows along the arc of the flow-guiding block to the two double-channel air duct sections 5 respectively. During this process, the existence of the sound-absorbing and flow-guiding block 10 separates each air flow. Due to the increase in the number of channels, the flow area of the air flow also increases accordingly, which will cause the flow velocity of the air flow to decrease, thereby reducing the formation of eddy currents. The outflow velocity of the air flow in the double channels is reduced to half or even more of the outflow velocity of the air flow in the traditional single channel. The reduction in velocity ensures the uniform distribution of the air flow, reduces energy loss, and reduces the generation of aerodynamic noise, greatly improving the performance and noise reduction effect of the entire wind tunnel system.

[0049] In some alternative embodiments, the sound-absorbing and flow-guiding block 10 is made of the same material as the sound-absorbing wedge (such as polyester fiber) to intercept the sound waves not absorbed by the sound-absorbing chamber 4, further enhancing the noise reduction effect and improving the experimental environment.

[0050] In this embodiment, there are two diffuser sections 6, and the two diffuser sections 6 are respectively connected to the two air duct outlets of the double-channel air duct section 5. The diffuser section 6 includes a first diffuser section 7, a second diffuser section 8 and an air outlet 9. The diffuser section 6 decelerates the high-speed air flow passing through the previous components to a lower speed through an expanding pipe, thereby increasing the static pressure and reducing energy loss. In addition, the diffuser section 6 can also isolate the interference of downstream unstable factors and has a certain backpressure resistance ability to ensure an effective uniform flow field in the wind tunnel test section. The second diffuser section 8 is located at the end of the wind tunnel and is used to further reduce the air flow velocity and lead the air flow out of the wind tunnel. This helps to reduce the noise inside and outside the wind tunnel and can effectively control the flow state of the air flow to ensure the stability and reliability of the wind tunnel system. The air outlet 9 is the exhaust port in the wind tunnel system, and its main function is to lead the air flow processed by the experimental section and the diffuser section 6 out of the wind tunnel. When necessary, a muffler can be installed at the air outlet 9 to further reduce the noise and ensure the low-noise operation of the wind tunnel.

[0051] As Figure 5 shown, in this embodiment, the power system is an axial flow fan installed in the first diffuser section 7, and the axial flow fan is connected to a servo motor 15 with a power of 2.4 kw. The rotation speed of the axial flow fan is controlled by the servo motor 15 to provide a wind field wind speed that meets the experimental requirements for the wind tunnel.

[0052] In a specific embodiment, as Figure 5As shown, a flow velocity sensor 11 is provided in the experimental section. The flow velocity sensor 11 is signal-connected to the computer 17 through the control unit 16. The flow velocity sensor 11 is used to measure the flow velocity of the released air flow. If the flow velocity is consistent with the input air flow velocity, the formal experiment can start.

[0053] In a specific embodiment, as Figure 5 shown, as a supporting system, a high-definition camera 12 and a microphone 14 are provided in the anechoic chamber 4. The microphone 14 is used to collect sound, and the high-definition camera 12 is used to collect images. Both are connected to the computer 17. The computer 17 processes the collected sound information and image information, converts them into experimental data such as visible decibel values or pictures, and automatically stores these experimental data in the hard disk of the computer 17 for later analysis and processing.

[0054] As Figure 5 shown, in this embodiment, the control system includes a control unit 16 and a computer 17. The control unit 16, the microphone 14, and the high-definition camera 12 are directly connected to the computer 17. The servo motor 15 and the flow velocity sensor 11 are indirectly connected to the computer 17 through the control unit 16.

[0055] The working principle of the control system in this embodiment is as Figure 6 shown. Through the control system, the start and stop of the experiment are controlled. The start of the control unit 16 drives the start of the flow velocity sensor 11 and the motor. Input the required motor speed for the experiment on the computer, and the information is transmitted to the motor. The motor starts and releases the air flow. At this time, the flow velocity sensor 11 starts to work and measures the flow velocity of the air flow. If the flow velocity is consistent with the input air flow velocity, the microphone 14 and the high-definition camera 12 start to work, and the formal experiment starts. Otherwise, readjust the motor speed and start again. The computer displays the sound decibel value collected by the microphone 14; the high-definition camera 12 takes multiple groups of experimental photos for experimental analysis. When the experiment ends, the control system automatically checks whether the experimental data is collected completely. If the experimental data is recorded completely, these data and pictures will be automatically saved to the corresponding files on the computer; otherwise, the computer displays a warning message, and relevant data needs to be continued to be supplemented, and the experiment needs to be restarted. After the experiment is completed, click the "Stop" button on the computer, and all components stop working. After turning off the power, the connection can be disconnected to end the experiment. After dealing with the experimental equipment and site, the analysis and processing of the experimental data can be carried out.

[0056] It should be understood that in practical applications, the noise reduction wind tunnel of the present invention can be applied to the experimental research of aeroacoustics. On the basis of the functions of a traditional wind tunnel, the structure of the diffuser section 6 is further optimized to make it a double-channel elbow and sound-absorbing materials that can reduce noise are attached to the wall of the pipe, which can effectively reduce the noise transmitted from the equipment to the wind tunnel experimental area and the background noise. The double-channel wind tunnel design enables a higher air flow velocity, better uniformity and stability, and the air flow velocity is increased from 30 m / s to 60 m / s.

[0057] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0058] The embodiments described above are only for describing the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A direct-flow dual-channel silencing wind tunnel, characterized in that, Comprising: An anechoic chamber (4) with anechoic wedges laid on the inner wall thereof; An air duct system, which includes an air inlet (1), a stabilization section (2), a contraction section (3), a test section, a double-channel air duct section (5) and two diffuser sections (6) connected in sequence; the test section is arranged in the anechoic chamber (4), the double-channel air duct section (5) has one air duct inlet and two air duct outlets, the two air duct outlets are symmetrically distributed on both sides of the air duct inlet and form a 90° angle with the air duct inlet; the two diffuser sections (6) are respectively connected to the two air duct outlets; A power system, which includes an axial flow fan installed in the diffuser section (6) and a servo motor (15) connected to the axial flow fan; A control system, which includes a control unit (16) and a computer (17) connected to the servo motor (15).

2. The direct-flow dual-channel silencing wind tunnel according to claim 1, wherein The diffuser section (6) includes a first diffuser section (7), a second diffuser section (8) and an air outlet (9); the first diffuser section (7) is connected to the double-channel air duct section (5) for reducing the air flow velocity; the second diffuser section (8) is used for further reducing the air flow velocity and guiding the air flow to be discharged outside the wind tunnel.

3. The direct-flow two-channel silencing wind tunnel according to claim 1, characterized in that, A sound-absorbing and flow-guiding block (10) is arranged at the bifurcation in the double-channel air duct section (5).

4. The direct-flow two-channel silencing wind tunnel according to claim 3, characterized in that, The sound-absorbing and flow-guiding block (10) has a streamlined flow-guiding surface, and its material is the same as that of the anechoic wedge.

5. The direct-flow two-channel silencing wind tunnel according to claim 1, wherein The anechoic wedge is composed of a base and a wedge part, the length of the base is 10 cm, and the length of the wedge part is 30 cm.

6. The direct-flow two-channel silencing wind tunnel according to claim 5, wherein, The anechoic wedges are arranged in a crisscross pattern.

7. The direct-flow two-channel sound-absorbing wind tunnel according to claim 1 or 5 or 6, characterized in that, The material of the anechoic wedge is polyester fiber.

8. The direct-flow two-channel silencing wind tunnel according to claim 1, wherein The air flow velocity range in the test section is 0.1 - 60 m / s, the flow velocity stability coefficient ≤ 0.5%, the flow velocity uniformity coefficient ≤ 1%, and the wind speed resolution is 0.1 m / s.

9. The direct-flow dual-channel silencing wind tunnel according to claim 1 or 8, characterized in that, A flow velocity sensor (11) is arranged in the test section, and the flow velocity sensor (11) is signal-connected to the computer (17) through the control unit (16).

10. The direct-flow double-channel silencing wind tunnel according to claim 1, characterized in that, It further includes a high-definition camera (12) and a microphone (14) arranged in the anechoic chamber (4), and the high-definition camera (12) and the microphone (14) are connected to the computer (17).

Images