Ground loudspeaker with evacuation indication function and application thereof

Abstract

The invention provides a ground loudspeaker with an evacuation indication function, an evacuation identification plate is arranged on the ground loudspeaker, a vibrator, a sound module and a main control circuit board are arranged in the ground loudspeaker, the vibrator is in contact with the evacuation identification plate and is used for converting a current signal of the sound module into mechanical vibration and transmitting the mechanical vibration to the evacuation identification plate, and the main control circuit board is connected with the sound module. The evacuation identification plate vibrates to make a sound; and the sound module is electrically connected with the main control circuit board and the vibrator and is used for decoding and amplifying a received sound signal sent by the main control circuit board and then providing the sound signal to the vibrator to drive the vibrator to work. According to the invention, the distance between the loudspeaker and audiences can be effectively shortened so as to ensure high definition, and the loudspeaker is mounted on the ground and is not limited by the mounting position of the loudspeaker; moreover, the loudspeaker has the functions of loudspeaking and visual guidance, and is especially suitable for being used in a large-scale indoor space.

Description

Technical Field

[0001] The invention belongs to the technical field of sound transmission devices, and in particular relates to a ground loudspeaker with an evacuation indication function and an application thereof. Background Art

[0002] In large indoor spaces such as railway waiting halls and exhibition centers, the clarity of internal broadcasting systems is often low. The root cause is that the speakers cannot be placed close to the audience. In tall and large spaces, speakers are usually hung on the top, side walls, or protruding local service buildings. The distance between the speakers and the audience is very long, and there is serious interference between the speakers. Hanging speakers from high places has aesthetic and safety issues. In addition, due to the limited lateral height, the coverage range of speakers installed on side walls and local service buildings is usually not far enough.

[0003] Ground emergency evacuation indicator lights are fire-fighting equipment that must be installed in large indoor spaces. Currently, existing indicator lights installed on the ground can usually only use visual guidance, which leads to reduced evacuation guidance efficiency in extreme cases with limited vision. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a floor speaker with evacuation indication function, which can effectively shorten the distance with the audience to ensure high clarity. The floor speaker is installed on the ground and is not restricted by the installation position of the speaker. The speaker also has sound amplification and visual guidance functions, and is particularly suitable for use in large indoor spaces.

[0005] The present invention is achieved through the following technical solutions:

[0006] A ground speaker with evacuation indication function, comprising a main housing, an evacuation identification plate, a vibrator, a sound module, a main control circuit board, a power module, a battery and a light module;

[0007] The evacuation identification plate is installed at the top port of the main shell;

[0008] The vibrator is arranged in the main housing and in contact with the evacuation identification plate, and is used to convert the current signal of the sound module into mechanical vibration and transmit it to the evacuation identification plate, so that the evacuation identification plate vibrates and emits sound;

[0009] The sound module is arranged in the main housing, electrically connected to the main control circuit board and the vibrator, and is used to decode and amplify the sound signal received from the main control circuit board, and then provide it to the vibrator to drive the vibrator to work;

[0010] The main control circuit board is arranged in the main housing, and its function is to integrate the functions of power supply rectification, network signal reception and transmission, emergency decision-making, etc.;

[0011] The power module is arranged in the main housing and is used to provide external power supply;

[0012] The battery is arranged in the main housing and is used to provide internal emergency power supply;

[0013] The lighting module is arranged in the main housing, electrically connected to the main control circuit board, and is used to illuminate the evacuation identification plate.

[0014] The above technical solution also includes a top annular metal cover plate, which is fixedly mounted on the main shell by screws and covers the edge of the evacuation identification plate, thereby protecting the edge of the evacuation identification plate.

[0015] In the above technical solution, the floor speaker also includes an embedded box for being preinstalled at the location to be installed. During installation, the main shell is fixedly installed in the embedded box by bolt connection or other connection methods.

[0016] In the above technical solution, the shape of the floor speaker of the present invention is not limited, and can be circular, rectangular, square or other shapes.

[0017] In the above technical solution, a spring base is also provided in the main shell, and the spring base is fixed between the main shell and the vibrator, so as to maintain an upward stress on the vibrator and ensure that the vibrator is firmly attached to the evacuation identification plate; the spring base preferably adopts a disc spring, which can effectively reduce the required height of the main shell.

[0018] In the above technical solution, a hard support plate and a flexible cushion layer are further provided on the bottom surface of the evacuation sign plate, and the flexible cushion layer is located between the hard support plate and the evacuation sign plate.

[0019] In the above technical solution, the edge of the hard support plate is installed on the main shell, and a first through hole for the vibrator to pass through is arranged on the hard support plate; the flexible pad layer is in the shape of a disc, and a second through hole for the vibrator to pass through is also arranged on the flexible pad layer, so that the vibrator can contact the evacuation identification plate through the hard support plate and the flexible pad layer.

[0020] In the above technical solution, a plurality of first hollow holes are evenly distributed on the hard support plate, and a plurality of second hollow holes are evenly distributed on the flexible cushion layer. The provision of these hollow holes can reduce the weight and material of the hard support plate and the flexible cushion layer, and can improve the vibration capacity of the evacuation sign plate.

[0021] In the above technical solution, the first through hole on the hard support plate is eccentrically arranged, and the vibrator is eccentrically arranged in the main shell so as not to block the indicating arrow on the evacuation identification plate.

[0022] In the above technical solution, the flexible cushion layer adopts a strip structure, that is, a plurality of flexible strips are arranged between the evacuation identification plate and the hard support plate to form a flexible cushion layer.

[0023] In the above technical solution, an optical sensor and an optical processing module are also provided in the main shell. The optical sensor is installed on the back of the evacuation sign plate, and its function is to record the image of the external environment in real time and transmit it to the optical processing module; the optical processing module has the function of processing and analyzing the image transmitted by the optical sensor.

[0024] In the above technical solution, the optical processing module processes and analyzes the image through a pre-trained model: on the one hand, it determines the number of people in the image to determine the number of people near the speaker, and transmits the judgment result to the main control circuit board; on the other hand, it determines whether there is an emergency such as fire or thick smoke through the image, and sends the judgment result to the main control circuit board.

[0025] In the above technical solution, the decision-making process of the main control circuit board is as follows:

[0026] The main control circuit board has two working states: normal state and emergency state:

[0027] (1) Under normal conditions, the main control circuit board receives the broadcast signal from the main control station through its own network transceiver module to realize the broadcast function of the speaker;

[0028] The main control circuit board determines the noise level of the crowd near the speaker based on the number of people near the speaker sent by the optical processing module and the relationship between the number of people and crowd noise set in advance, and then sends a volume control instruction to the sound module to achieve dynamic adjustment of the speaker volume;

[0029] The main control circuit board sends an early warning signal to the main control console through its own network transceiver function based on the judgment result of the emergency state sent by the optical processing module.

[0030] (2) In an emergency, the main control circuit board controls the loop playback of the pre-set evacuation guidance sound, or the main control console controls the playback content of the local speakers in a personalized manner;

[0031] There are two ways for the main control circuit board to enter the emergency state: the first is centralized control, which receives the control signal sent by the main control console through the network transceiver module to switch to the emergency state; the second is that the main control circuit board sends a warning signal to the main control console and automatically switches to the emergency state after receiving no feedback for a period of time.

[0032] The advantages and beneficial effects of the present invention are:

[0033] The floor loudspeaker with evacuation indication function of the present invention can be embedded in the ground of large public spaces with high heights, such as railway waiting halls and exhibition centers, to construct a public broadcasting system, which can effectively shorten the distance to the audience and ensure high clarity. It is installed on the ground and is not restricted by the installation position of the loudspeaker; and the loudspeaker has both sound amplification and visual guidance functions, and is particularly suitable for use in large indoor spaces.

[0034] The floor speaker of the present invention is also provided with an optical sensor and an optical processing module. The optical sensor is installed on the back of the evacuation sign board, and can record the image of the external environment in real time and transmit it to the optical processing module; the optical processing module processes and analyzes the image transmitted by the optical sensor, and through the pre-trained model, on the one hand, it can judge the number of people in the image to judge the number of people near the speaker, and transmit the judgment result to the main control circuit board; on the other hand, it can judge whether there is an emergency such as fire or thick smoke through the image, and send the judgment result to the main control circuit board. Then, the main control circuit board judges the noise level of the crowd near the speaker according to the judgment result of the number of people near the speaker sent by the optical processing module, through the relationship between the number of people and the crowd noise set in advance, and then sends a volume control instruction to the sound module, thereby realizing dynamic adjustment of the speaker volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is an exploded structural diagram of a ground loudspeaker with an evacuation indication function according to the first embodiment of the present invention.

[0036] Figure 2 It is a structural schematic diagram of a floor loudspeaker with an evacuation indication function according to the first embodiment of the present invention (the evacuation identification plate is in a separated state).

[0037] Figure 3 It is a schematic diagram of the structure of a ground speaker with an evacuation indication function according to the first embodiment of the present invention.

[0038] Figure 4 It is a structural schematic diagram (rectangular structure) of a floor loudspeaker with evacuation indication function according to the first embodiment of the present invention.

[0039] Figure 5 It is a schematic diagram of setting a hard support plate and a flexible cushion layer on the bottom surface of the evacuation sign plate in Example 3.

[0040] Figure 6 It is a schematic diagram of setting a hard support plate and a flexible cushion layer on the bottom surface of the evacuation sign plate in the fourth embodiment.

[0041] Figure 7 It is an exploded structural diagram of a ground loudspeaker with an evacuation indication function according to a fifth embodiment of the present invention.

[0042] Figure 8 It is a schematic diagram of an application scenario of the ground loudspeaker with evacuation indication function of the present invention.

[0043] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with specific embodiments.

[0045] Embodiment 1

[0046] Referring to the accompanying drawings, the present invention designs a ground speaker with evacuation indication function, including an embedded box 1, a main shell 2, an evacuation identification plate 3, a vibrator 4, a sound module 5, a main control circuit board 6, a power module 7, a battery 8 and a light module 9.

[0047] The embedded box 1 has the function of being fixed in advance and can be pre-installed at the location to be installed using adhesives such as concrete.

[0048] The main housing 2 is preferably in a cone-shaped bowl shape, and its function is to provide a mounting base, and its interior is used for integrated mounting of various functional components. During installation, the main housing 2 is fixedly mounted in the embedded box 1 by bolt connection or other connection methods (e.g., snap connection, thread connection, adhesive connection).

[0049] The evacuation sign plate 3 is installed at the top port of the main housing 2, and is made of transparent or translucent glass. Its function is to transmit light and indicate the evacuation direction. When used in combination with the vibrator 4, the mechanical vibration carrying the sound signal can be transmitted to the air under the excitation of the vibrator 4, thereby realizing the function of the speaker. Preferably, the evacuation sign plate 3 is connected to the top port of the main housing 2 by structural adhesive, or other installation and connection methods are adopted, which are not limited.

[0050] The vibrator 4 is disposed in the main housing 2 and in contact with the evacuation sign plate 3. Its function is to convert the current signal of the sound module 7 into mechanical vibration and transmit it to the evacuation sign plate 3, so that the evacuation sign plate 3 vibrates and emits sound. Preferably, the vibrator 4 is connected to the bottom surface of the evacuation sign plate 3 by using an adhesive with a high hardness after solidification, so as to facilitate fixation and transmission of mechanical vibration.

[0051] The sound module 5 is arranged in the main housing 2, and is electrically connected to the main control circuit board 6 and the vibrator 4. It is used to decode and amplify the sound signal received from the main control circuit board 6, and then provide it to the vibrator 4 to drive the vibrator 4 to work.

[0052] The main control circuit board 6 is arranged in the main housing 2, and its function is to integrate power supply rectification, network signal reception and transmission, emergency decision-making and other functions.

[0053] The power module 7 is arranged in the main shell 2, and its function is to provide external power supply, that is, the external power line is electrically connected to the input end of the power module 7 (a wire threading hole is provided on the main shell 2, which is used to lead the cable at the input end of the power module 7 out of the main shell 2, so as to be connected to the external power line). The power module 7 converts the external power supply (usually AC220V) into a DC power supply for each electrical component inside the main shell 2, thereby supplying power to each electrical component.

[0054] The battery 8 is disposed in the main housing 2 and its function is to provide internal emergency power supply.

[0055] The lighting module 9 is disposed in the main housing 2 , and is electrically connected to the main control circuit board 6 , and is used to illuminate the evacuation identification plate 3 .

[0056] Furthermore, the shape of the floor speaker of the present invention is not limited, except for the following Figure 1 -Attached Figure 3 The circle shown can also be a rectangle (see attached Figure 4 ), square or other shapes.

[0057] Furthermore, as a priority, a spring base 10 is also provided in the main housing 2 , and the spring base 10 is fixed between the main housing 2 and the vibrator 4 , thereby maintaining an upward stress on the vibrator 4 , ensuring that the vibrator 4 and the evacuation identification plate 3 are firmly attached.

[0058] Furthermore, as a priority, an optical sensor 12 and an optical processing module 13 are also provided in the main shell 2. The optical sensor 12 is installed on the back of the evacuation sign plate 3 (specifically, it is installed on the back of the indicator arrow part of the evacuation sign plate 3 with higher transparency). Its function is to record the image of the external environment in real time and transmit it to the optical processing module 13; the optical processing module 13, its function is to process and analyze the image transmitted by the optical sensor 12. Through the pre-trained model, on the one hand, it can judge the number of people in the image to judge the number of people near the speaker, and transmit the judgment result to the main control circuit board 6; on the other hand, it can judge whether there is an emergency such as fire or thick smoke through the image, and send the judgment result to the main control circuit board 6.

[0059] Embodiment 2

[0060] Furthermore, the decision-making process of the main control circuit board 6 is as follows:

[0061] The main control circuit board 6 has two working states: normal state and emergency state.

[0062] (1) Under normal circumstances, the main control circuit board 6 receives the broadcast signal sent by the main control station through its own network transceiver module (such as WIFI, Bluetooth, Zigbee), thereby realizing the broadcast function of the speaker, which can be in the form of unified broadcast or individual broadcast of local speakers.

[0063] The main control circuit board 6 determines the noise level of the crowd near the speaker based on the result of the number of people near the speaker sent by the optical processing module 13 and the relationship between the preset number of people and crowd noise, and then sends a volume control instruction to the sound module 5, thereby realizing dynamic adjustment of the speaker volume.

[0064] The main control circuit board 6 sends an early warning signal to the main control station through its own network transceiver function according to the judgment result of the emergency state sent by the optical processing module 13.

[0065] (2) In an emergency, the main control circuit board 6 controls the loop playback of the pre-set evacuation guidance sound, and the main control console can also personalize the playback content of the local speakers.

[0066] There are two ways for the main control circuit board 6 to enter the emergency state: the first is centralized control, which can receive the control signal sent by the main control console through a network transceiver module (WIFI, Bluetooth, Zigbee, etc.), thereby switching to the emergency state; the second is that the main control circuit board 6 sends a warning signal to the main control console and automatically switches to the emergency state after no feedback is received for a period of time.

[0067] Embodiment 3

[0068] Furthermore, in order to ensure that the evacuation sign plate 3 has good vibration and sound generation efficiency, the evacuation sign plate 3 is relatively thin, so its bearing capacity is limited. When a person or other object steps on the evacuation sign plate 3, the evacuation sign plate 3 faces the risk of being damaged or even broken.

[0069] For this purpose, see Appendix Figure 5 In this embodiment, on the basis of the above embodiment, a hard support plate 14 and a flexible cushion layer 15 are further provided on the bottom surface of the evacuation sign plate 3, and the flexible cushion layer 15 is located between the hard support plate 14 and the evacuation sign plate 3; wherein, the hard support plate 14 is made of a metal material with good rigidity, and is used to provide a hard support foundation with high strength for the evacuation sign plate 3; the material of the flexible cushion layer 15 can be rubber, and the purpose is to flexibly support the evacuation sign plate 3, and flexibly isolate the evacuation sign plate 3 and the hard support plate 14, so as to prevent the hard support plate 14 from interfering with the vibration and sound of the evacuation sign plate 3. When a person or other object steps on the evacuation sign plate 3, the hard support plate 14 supports the evacuation sign plate 3 through the flexible cushion layer 15, so as to prevent the evacuation sign plate 3 from being excessively deformed, causing danger or product damage.

[0070] Furthermore, the edge of the hard support plate 14 is installed on the main shell 2, and a first through hole 14.1 for the vibrator 4 to pass through is provided on the hard support plate 14; the flexible pad 15 is in the shape of a disc, and a second through hole 15.1 for the vibrator 4 to pass through is also provided on the flexible pad 15, so that the vibrator 4 can contact the evacuation identification plate 3 through the hard support plate 14 and the flexible pad 15.

[0071] Furthermore, the hard support plate 14 is evenly provided with a plurality of first hollow holes 14.2, and correspondingly, the flexible cushion layer 15 is evenly provided with a plurality of second hollow holes 15.2. The provision of these hollow holes can reduce the weight and material of the hard support plate and the flexible cushion layer, and can improve the vibration capacity of the evacuation identification plate 3.

[0072] Embodiment 4

[0073] See attached Figure 6 This embodiment is consistent with the basic principle of the third embodiment, and a hard support plate 14 and a flexible cushion layer 15 are also arranged on the bottom surface of the evacuation sign plate 3. The difference between this embodiment and the third embodiment is that the first through hole 14.1 on the hard support plate 14 is eccentrically arranged, so that the vibrator 4 passes through the eccentric first through hole 14.1 and acts on the eccentric position of the evacuation sign plate 3 (the vibrator 4 is eccentrically arranged in the main housing), so as not to block the indicating arrow on the evacuation sign plate 3; in addition, the flexible cushion layer 15 of this embodiment adopts a strip structure, that is, a plurality of strip-shaped flexible strips are arranged between the evacuation sign plate 3 and the hard support plate 14, so as to form a flexible cushion layer.

[0074] Embodiment 5

[0075] See attached Figure 7 , which is a preferred embodiment of the present invention. On the basis of the above embodiment, this embodiment provides a ground speaker with evacuation indication function, including an embedded box 1, a main shell 2, an evacuation identification plate 3, a vibrator 4, a sound module 5, a main control circuit board 6, a power module 7, a battery 8, a light module 9, a spring base 10, an optical sensor 12, an optical processing module 13, a hard support plate 14, a flexible pad 15 and a top annular metal cover 16.

[0076] Compared with the above embodiment, the present embodiment is additionally provided with a top annular metal cover plate 16, which is fixedly mounted on the main housing 2 by 6 screws, covering the edge of the evacuation identification plate 3, thereby protecting the edge of the evacuation identification plate.

[0077] In this embodiment, the spring base 10 preferably adopts a disc spring, which can effectively reduce the required height of the main housing 2.

[0078] In this embodiment, the hard support plate 14 and the flexible cushion layer 15 preferably adopt the solution of the fourth embodiment.

[0079] In this embodiment, the power module 7 may also be located outside the main housing 2 and the embedded box 1 .

[0080] Embodiment 6

[0081] The application scenarios of the floor speaker of the present invention are as follows:

[0082] When used, the floor speaker of the present invention is embedded in the floor of a large public space with a high height, such as a railway waiting hall, a convention center, etc. The floor speaker can be combined with the floor tile grid of the public space, and a rectangular, cylindrical, etc. floor speaker can be used to replace part of the floor tiles (see attached Figure 8 , wherein the number 00 represents floor tiles, and 01 represents the floor speaker of the present invention); a plurality of the floor speakers are arranged in an array, so as to construct a public broadcasting system by means of the vibration floor speaker device arranged in this array, so that the floor speaker of the present invention is very close to the audience, so that broadcasting can be performed at a very low volume, reducing mutual interference between long-distance speakers, being able to achieve a wide coverage range, and greatly improving the clarity of the audience.

[0083] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A ground speaker with evacuation indication function, characterized in that: It includes a main housing, an evacuation identification plate, a vibrator, a sound module, a main control circuit board, a power module, a battery and a lighting module; The evacuation identification plate is installed at the top port of the main shell; The vibrator is arranged in the main housing and in contact with the evacuation identification plate, and is used to convert the current signal of the sound module into mechanical vibration and transmit it to the evacuation identification plate, so that the evacuation identification plate vibrates and emits sound; The sound module is arranged in the main housing, electrically connected to the main control circuit board and the vibrator, and is used to decode and amplify the sound signal received from the main control circuit board, and then provide it to the vibrator to drive the vibrator to work; The main control circuit board is arranged in the main housing, and its function is to integrate the functions of power supply rectification, network signal reception and transmission, emergency decision-making, etc.; The power module is arranged in the main housing and is used to provide external power supply; The battery is arranged in the main housing and is used to provide internal emergency power supply; The lighting module is arranged in the main housing, electrically connected to the main control circuit board, and is used to illuminate the evacuation identification plate.

2. The ground speaker with evacuation indication function according to claim 1, characterized in that: It also includes a top annular metal cover sheet, which is fixed on the main shell body by screws and covers the edge of the evacuation identification plate, thereby protecting the edge of the evacuation identification plate.

3. The ground speaker with evacuation indication function according to claim 1, characterized in that: The floor speaker also includes an embedded box for being pre-installed at a location to be installed. During installation, the main housing is fixedly installed in the embedded box by bolt connection or other connection methods.

4. The ground speaker with evacuation indication function according to claim 1, characterized in that: A spring base is also provided in the main housing, and the spring base is fixed between the main housing and the vibrator, so as to maintain an upward stress on the vibrator and ensure that the vibrator is firmly attached to the evacuation identification plate; the spring base is preferably a disc spring.

5. The ground speaker with evacuation indication function according to claim 1, characterized in that: A hard support plate and a flexible cushion layer are also arranged on the bottom surface of the evacuation identification plate, and the flexible cushion layer is located between the hard support plate and the evacuation identification plate.

6. The ground speaker with evacuation indication function according to claim 5, characterized in that: The edge of the hard support plate is mounted on the main shell, and a first through hole for the vibrator to pass through is provided on the hard support plate; a second through hole for the vibrator to pass through is also provided on the flexible cushion layer, so that the vibrator contacts and acts on the evacuation identification plate through the hard support plate and the flexible cushion layer; The first through hole on the hard support plate is eccentrically arranged, and the vibrator is eccentrically arranged in the main housing so as not to block the indicating arrow on the evacuation identification plate; The flexible pad layer is in the shape of a disc, or in the shape of a strip.

7. The ground speaker with evacuation indication function according to claim 1, characterized in that: An optical sensor and an optical processing module are also provided in the main housing. The optical sensor is installed on the back of the evacuation identification plate, and its function is to record the image of the external environment in real time and transmit it to the optical processing module; The optical processing module is used to process and analyze the images transmitted by the optical sensor.

8. The ground speaker with evacuation indication function according to claim 7 is characterized in that: The optical processing module processes and analyzes the image through a pre-trained model: on the one hand, it determines the number of people in the image to determine the number of people near the speaker, and transmits the judgment result to the main control circuit board; on the other hand, it determines whether there is an emergency such as fire or thick smoke through the image, and sends the judgment result to the main control circuit board.

9. The ground speaker with evacuation indication function according to claim 8, characterized in that: The decision-making process of the main control circuit board is as follows: The main control circuit board has two working states: normal state and emergency state: (1) Under normal conditions, the main control circuit board receives the broadcast signal from the main control station through its own network transceiver module to realize the broadcast function of the speaker; The main control circuit board determines the noise level of the crowd near the speaker based on the number of people near the speaker sent by the optical processing module and the relationship between the number of people and crowd noise set in advance, and then sends a volume control instruction to the sound module to achieve dynamic adjustment of the speaker volume; The main control circuit board sends an early warning signal to the main control console through its own network transceiver function based on the judgment result of the emergency state sent by the optical processing module. (2) In an emergency, the main control circuit board controls the loop playback of the pre-set evacuation guidance sound, or the main control console controls the playback content of the local speakers in a personalized manner; There are two ways for the main control circuit board to enter the emergency state: the first is centralized control, which receives the control signal sent by the main control console through the network transceiver module to switch to the emergency state; the second is that the main control circuit board sends a warning signal to the main control console and automatically switches to the emergency state after receiving no feedback for a period of time.

10. An application method of a ground loudspeaker with evacuation indication function, characterized in that: The floor loudspeaker described in claim 1 is embedded in the floor of a high and large public space such as a railway waiting hall, a convention and exhibition center, and a plurality of the floor loudspeakers are arranged in an array to construct a public broadcasting system.

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