JP2009045302A - Loudspeaker control device and loudspeaker system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a loudspeaker system for forming an acoustic space more comfortable to users from different locations of the ears of the users on a seat. <P>SOLUTION: The loudspeaker system includes loudspeakers provided at a seat body and changeable in direction, a loudspeaker direction-adjusting means for adjusting the direction of the loudspeakers, a position-detecting means for detecting the location of a headrest of the seat body, and a control means for controlling the loudspeaker direction-adjusting means from the detection result of the position-detecting means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a speaker device that provides audio to a user sitting on a seat.

  A speaker device that is provided in a seat of a vehicle and provides sound to a user sitting there is more comfortable by providing individual sound for each user or directly providing sound to the user's ear. It is a useful device capable of forming a simple acoustic space. In Patent Document 1, the position of a speaker can be appropriately adjusted for each user having a different height by being attached to a headrest of a seat and appropriately adjusting the curvature of the arm member (see particularly FIGS. 7 and 8). . This makes it possible to individually provide music selected by the user sitting on the seat.

Also, Patent Document 2 discloses a technique related to a speaker device that is a similar speaker device and forms a more comfortable acoustic space. In this technology, a detection device that accurately detects the user's head position is provided, and the frequency characteristics of the output sound from the speaker are corrected based on the detected head position. Thereby, an acoustic space suitable for each user is formed. A technique for detecting the head position of a user sitting on a seat is disclosed in Patent Document 3. In this technique, the position of the head is detected based on the seat position, the backrest angle, and the headrest height. Further, Patent Document 4 discloses a configuration of a speaker device that protrudes from a headrest and emits sound from the vicinity of a user's ear.
JP 2005-167378 A Japanese Patent Laid-Open No. 7-131883 JP-A-7-193900 JP 2002-191469 A

  In the conventional speaker device provided in the seat, the height of the speaker is set to form a more comfortable acoustic space in consideration of the fact that the position of the head varies depending on individual differences when the user sits on the seat. Is changed according to the position of the user's head. However, in the speaker device provided in the seat, the direction is generally set so that sound is provided to the user's head position, but the direction is mainly fixed.

  In such a case, even if the height of the speaker is changed according to the position of the user's head, the direction of the speaker, more precisely, the direction in which the sound emitted from the speaker travels (sound axis direction) is directed toward the user's ear position. It will not be in the state. For this reason, the effect that the user can feel with the sound emitted to the user's ear for a predetermined purpose cannot be sufficiently produced, and formation of a comfortable acoustic space for the user is hindered.

  In view of the above problems, the present invention provides a speaker device capable of forming a more comfortable acoustic space for each user, based on the fact that the position of the ear changes for each user sitting on the seat. With the goal.

In the present invention, in order to solve the above-described problems, the direction of the speaker provided in the seat is controlled according to the position of the headrest having a function of mainly supporting the user's head in the seat, in particular, the vertical position thereof. It was decided. That is, according to the present invention, by associating the position of the headrest with the position of the user's head, the user's ear position can be easily identified and reflected in the optimum direction of the speaker.

  Therefore, when the present invention is first grasped from the side of the speaker control device that controls the direction of the speaker, the present invention capable of solving the above problems can detect the position of the headrest that can support the head of the user sitting on the seat. This is a speaker control device having control means for controlling speaker adjustment means for adjusting the direction of the speaker provided in the seat based on the detection result of the position detection means. In this way, by controlling the position of the headrest on which the user sits in association with the direction of the speaker, it is possible to provide sound in an optimal state with respect to the user's ear from the speaker, thereby forming a more comfortable acoustic space Contributes to

  Next, the present invention can also be grasped from the side of the speaker device responsible for sound output. Specifically, the present invention provides a speaker that is provided in a seat body and has a variable orientation, a speaker direction adjusting unit that adjusts the direction of the speaker, a position detecting unit that detects a position of a headrest of the seat body, And a control unit that controls the speaker orientation adjustment unit based on a detection result of the position detection unit.

  In addition, the present invention provides a seat body, a speaker provided in the seat body, the orientation of which is variable, a headrest provided in the seat body and capable of supporting a user's head, and adjusting the orientation of the speaker. The speaker device may include a speaker direction adjusting unit, a position detecting unit that detects the position of the headrest, and a control unit that controls the speaker direction adjusting unit based on a detection result of the position detecting unit.

  The speaker constituting the speaker device according to the present invention is provided in the main body of the seat, and its direction is variable so as to deliver sound to the user's ear. Examples of the installation position of the speaker include a position near the shoulder and mouth of the seat body, which is one of the positions closest to the user's ear position, but other installation positions may of course be used. The user can enjoy various sound effects by receiving the sound emitted from the speaker directly by the ear, that is, by receiving the direct sound instead of the reflected sound.

  Here, the direction of the speaker can be adjusted by the speaker direction adjusting means. Thereby, the direction is adjusted so that the speaker faces the user's ear position. The control means controls the orientation adjustment of the speaker. The control means controls the direction of the speaker via the speaker direction adjusting means based on the position of the headrest of the seat detected by the position detecting means. This is because the position of the headrest is a parameter closely related to the position of the user's head, which makes it possible to easily and accurately detect the user's ear position. Therefore, the control means can set the direction of the speaker with respect to the user's ear position based on the position of the headrest.

  As described above, in the speaker device according to the present invention, the adjustment of the direction of the speaker is controlled in accordance with the ear position of each user, so that a sound suitable for the user is always provided from the speaker. As a result, the user can enjoy various acoustic effects by sound from the speaker in an optimal state.

  Here, in the speaker device, the control unit may control the direction of the speaker mechanically so that the speaker faces the user's ear position in accordance with a change in the position of the headrest. . That is, by adjusting the position of the headrest and the direction of the speaker mechanically, it is possible to more easily control the adjustment of the direction of the speaker.

The speaker device described above further includes position estimation means for estimating a position of a user's ear based on the position of the headrest detected by the position detection means, and the control means is configured by the position estimation means. You may make it control the direction of this speaker via the said speaker direction adjustment means so that the said speaker may face the estimated user's ear position. That is, the position estimation means actively estimates the ear position of the user from the position of the headrest detected by the position detection means, and the control means controls the adjustment of the direction of the speaker based on the estimation result. For example, a form in which the vertical position of the headrest is detected by a sensor and the direction of the speaker is changed by a motor or the like based on the detection result corresponds to the speaker device according to the present invention.

  Here, in the speaker device described above, when the direction of the speaker is controlled by the speaker direction control means, and when the direction of the speaker is controlled by the control means, the distance from the speaker to the user's ear position is set. Based on this, sound pressure adjusting means for adjusting the output sound pressure of the speaker may be further provided. As described above, the feature point of the speaker device according to the present invention is that the direction of the speaker is changed according to the position of the headrest. At this time, if the orientation of the speaker is changed, the distance between the speaker and the user's ear position varies, and in some cases, the formation of the acoustic space of the user may be greatly affected. One of the parameters forming the acoustic space is the volume of output sound. Therefore, in the speaker device according to the present invention, the output sound pressure of the speaker is adjusted by the sound pressure adjusting means based on the distance between the speaker and the user's ear position, in other words, based on the direction of the speaker. As a result, the acoustic space provided to the user can be more suitably maintained.

  Moreover, in order to make the sound effect by the sound emitted from the speaker more suitable, an audio signal related to the distance between the speaker and the user's ear position may be corrected as appropriate. That is, in the above-described speaker device, when the direction of the speaker is controlled by the control means, among the audio signals supplied to the speaker, a predetermined audio signal related to the distance from the speaker to the user's ear position. May be further provided with a sound signal correcting means for correcting the sound based on the distance between the speaker and the user's ear position.

  The predetermined audio signal is an audio signal related to the distance between the speaker and the user's ear position, that is, an audio signal that is preferably corrected to a more appropriate state when the distance fluctuates. In this way, it is possible to deliver the sound from the speaker to the user's ear position in a more favorable state by adjusting the direction of the speaker, and the delivered sound can be transmitted between the speaker and the user's ear position. Therefore, the acoustic space provided to the user is more suitable.

  Here, the predetermined audio signal will be described in more detail. First, as the predetermined audio signal, an audio signal for removing at least a part of a reflected sound generated by output sound from another speaker different from the speaker, the speaker provided in the seat body; A reflection-removed sound signal formed by a head-related transfer function corresponding to the distance to the user's ear position can be mentioned. This reflection removal sound signal is a signal for forming a removal sound whose phase is substantially reversed from the reflection sound that reaches the user in order to cancel the reflection sound, and corresponds to the distance between the speaker and the user's ear position. Determined by the head-related transfer function. The reflection removal sound by this reflection removal sound signal is delivered directly to the user's ear, so that unnecessary reflection sound is effectively removed. Therefore, when the predetermined sound signal is a reflection-removed sound signal, the sound signal correcting unit resets the head-related transfer function based on the distance between the speaker provided on the seat body and the user's ear position. Thus, it is possible to provide a sound for removing a more appropriate reflected sound from the speaker to the user's ear.

Secondly, as the predetermined sound signal, the predetermined sound signal may be a sound effect signal for giving a sound effect to output sound from another speaker different from the speaker. This sound effect signal is, for example, a signal for imparting a sound effect that matches the user's preference, and important elements for generating the sound effect are portions relating to the phase and sound pressure of the sound effect signal. In particular, when the sound effect is given to main sound output from a speaker different from the speaker, the timing at which the main sound and sound effect arrive at the user's ear position, and the sound effect at that time The strength of is important. Therefore, when the predetermined sound signal is a sound effect signal, the sound signal correction means relates to the phase and sound pressure of the sound effect signal based on the distance between the speaker provided in the seat body and the user's ear position. At least one of the portions may be adjusted. By doing in this way, it becomes possible to provide the sound for a more suitable acoustic effect with respect to a user's ear from a speaker.

  Here, in the speaker device up to the above, when the position of the headrest is at the uppermost position, the control means has a predetermined uppermost position that is the ear position of the user when the height of the user is 178 cm. The direction of the speaker may be controlled so as to face the ear position. Further, when the headrest is at the lowest position, the control means is arranged so that the direction of the speaker is directed to a predetermined lowest ear position that is the ear position of the user when the height of the user is 144 cm. The direction of the speaker may be controlled.

  The height of 178 cm in the former is the upper limit of 2σ in the normal distribution of the height of Japanese men. Therefore, by setting 2σ of the normal distribution of the height of the Japanese male as the uppermost position of the headrest, it is possible to appropriately direct the speaker to the ear position of at least about 95% of the Japanese male. Since women are statistically shorter than men, setting the position of the headrest in this way would make it possible to appropriately set the speaker orientation for a larger percentage of women.

  The height of 144 cm in the latter is the lower limit of 2σ in the normal distribution of the height of Japanese women. Therefore, by setting 2σ of the normal distribution of the height of Japanese women as the lowest position of the headrest, it becomes possible to properly orient the speaker with respect to the ear position of at least about 95% of Japanese women. . Since males are statistically taller than females, setting the position of the headrest in this way would make it possible to appropriately set the orientation of the speakers for more males.

  Furthermore, in the speaker device according to the present invention, depending on the region or country in which the speaker device is used and the normal distribution of the height of the user who uses the speaker device, the uppermost position and the lowermost position of the headrest as described above. The position may be determined. Generally, since males are statistically taller than females, it is preferable to determine the highest position according to the normal distribution of male user's height and the lowest position according to the normal distribution of female user's height. For example, in the United States, the uppermost position is 188 cm and the lowermost position is 147 cm.

  Based on the fact that the position of the ear changes for each user sitting on the seat, it is possible to provide a speaker device capable of forming a more comfortable acoustic space for each user.

  Here, an embodiment of a speaker device according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a speaker device according to the present invention provided in a seat 1 on which a user sits. The seat 1 is mainly composed of a seat body 3 and a headrest 2, and a user can sit on the seat body 3 and have the head supported by the headrest 2. The headrest 2 is disposed at an upper position of the seat body 3 via the two mounting feet 2 a and can move up and down with respect to the seat body 3. This is mainly for the purpose of enabling the user sitting on the seat 1 to adjust the position of the headrest 2 suitable for supporting his / her head. Examples of the seat 1 include seats for vehicles such as vehicles and trains, and seats installed in buildings such as theaters, and may be seats for other purposes.

  The seat speakers 4 constituting the speaker device according to the present invention are respectively provided on the left and right sides of the shoulder portion of the seat body 3, and the seat speakers 4 output audio signals supplied from the audio reproduction device 20 as audio. Therefore, when the user sits on the seat 1, it is possible to hear the sound emitted from the seat speaker 4. Further, the seat speaker 4 is adjusted so that its sound axis is directed toward the ear position of the user sitting on the seat 1 (see FIG. 2, details will be described later). ). As a result, the user can directly hear the sound output from the seat speaker 4. Further, a speaker that converts the audio signal supplied from the audio reproducing device 20 into audio and provides it to the user is provided in addition to the seat speaker 4, but this is not shown. For example, although not illustrated, a speaker or the like that can provide sound from the front to the user sitting on the seat 1 may be further provided.

  Here, the orientation adjustment of the seat speaker 4 will be described in detail. The sound emitted from the speaker 4 is particularly preferably delivered directly to the user's ear. For example, as the sound, unnecessary reflected sound generated by sound output from a speaker (not shown) other than the seat speaker 4 (for example, when the seat 1 is a seat provided in the vehicle, Reflection-removed sound for removing unnecessary reflected sound generated by the reflection of sound, and sound effect for generating an acoustic effect that matches the user's preference. Such voice can be delivered directly to the user's ears, thereby exhibiting its original effect.

  Therefore, if the sound axis direction of the seat speaker 4 deviates from the ear position of the user sitting on the seat 1, it is difficult for the user to fully enjoy the above effect due to the influence of the directivity of the seat speaker 4. Therefore, in the speaker device according to the present invention, the orientation of the seat speaker 4 is adjusted according to the position of the user's ear. The mechanism for adjusting the orientation will be further described with reference to FIG.

  The seat speaker 4 is rotatably installed in the seat body 3. Then, the rotation is performed in the direction in which the surface (usually the front surface) from which the sound of the seat speaker 4 is output can follow the user's ear position, with the rotation shaft 8 as the rotation center. The rotating shaft 8 connects the left and right seat speakers 4, and a power transmission unit 7 having a deceleration function is provided in the middle of the rotation shaft 8, and is connected to the motor 5 as a driving device via the power transmission unit 7. Is done. Therefore, the orientation of the seat speaker 4 is adjusted by driving the motor 5. The motor 5, the power transmission unit 7, and the rotation shaft 8 are provided in the seat body 3.

  Further, a position sensor 6 that detects a relative vertical position of the headrest 2 with respect to the seat body 3 is provided in the seat body 3. The position sensor 6 is a sensor composed of, for example, a linear scale, and detects how much the headrest 2 is moved with respect to the seat body 3 by detecting the position of the mounting foot 2a. It is possible. Since the vertical position of the headrest 2 corresponds to the user's head position, the headrest 2 is a parameter for easily estimating the user's ear position from the vertical position through the user's head position. The position sensor 6 is electrically connected to the microcomputer 10, and the microcomputer 10 acquires the detected vertical position.

The microcomputer 10 is also electrically connected to the motor 5, and the direction of the seat speaker 4 is adjusted by issuing a drive command to the motor 5. Here, the outline of the orientation adjustment of the seat speaker 4 will be described with reference to FIG. FIG. 2 shows a state in which the state of the seat 1 when the two-entry users A and B are sitting on the seat 1 and the orientation of the seat speaker 4 are compared. In addition, since the user A is shorter than the user B, the state where the head position is lower than the user B is shown in FIG.

  When the head position when sitting on the seat 1 is different due to the difference in height, the user adjusts the vertical position of the headrest 2 so that his / her head is sufficiently supported. In the state illustrated in FIG. 2, the head positions of the user A and the user B are different so that the vertical position of the headrest 2 is adjusted to be higher by the amount of Δh. At this time, the microcomputer 10 detects the vertical position of the headrest 2 via the position sensor 6 to estimate the user's head position and also the ear position, so that the sound axis of the seat speaker 4 faces the ear position. Next, a drive command is issued to the motor 5. As a result, the direction of the seat speaker 4 corresponding to the user B is directed upward by Δθ from the direction of the seat speaker 4 corresponding to the user A.

  The flow of the process of adjusting the orientation of the seat speaker 4 by the microcomputer 10 will be described in detail with reference to FIG. Note that the speaker orientation adjustment process shown in FIG. 3 is a routine that is repeatedly executed by the microcomputer 10 at a constant cycle.

  First, in S101, the vertical position of the headrest 2 is detected. This is done via the position sensor 6 as described above. When the process of S101 ends, the process proceeds to S102. In S102, the ear position of the user is estimated based on the vertical position of the headrest 2 detected in S101. Specifically, the microcomputer 10 has a control map in which the vertical position is associated with the user's ear position, and the user's ear position is estimated by referring to the control map according to the vertical position of the headrest 2. Is done. In estimating the user's ear position, not only the vertical position of the headrest 2 but also other parameters may be considered. For example, the estimated ear position may be corrected by further considering information regarding the user's gender input separately from the user, the inclination of the seat body 3 detected by a separately provided sensor, and the like. When the process of S102 ends, the process proceeds to S103.

  In S103, support for rotational driving is given to the motor 5 so that the sound axis of the seat speaker 4 faces the ear position of the user estimated in S102. As a result, the seat speaker 4 is driven to rotate about the rotation axis 8 and its orientation is set with respect to the user's ear position. As a result, different orientations are set for user A and user B, as shown in FIG. When the process of S103 ends, the process proceeds to S104.

  In S104, it is determined whether or not an audio signal is currently provided from the audio reproducing device 20 to the seat speaker 4 and audio is being reproduced there. That is, it is determined whether or not audio is provided to the user through the seat speaker 4. If it is determined that the sound is being reproduced, the process proceeds to S105, and if it is determined that the sound is not being reproduced, the speaker orientation adjustment process is terminated.

  Here, each process of S105-S107 is a process regarding the correction | amendment and adjustment of the audio | voice signal for forming the audio | voice provided with respect to a user from the seat speaker 4. FIG. These processes are performed considering that the distance between the seat speaker 4 and the user's ear position (hereinafter referred to as “predetermined distance”) has been changed by adjusting the direction of the seat speaker 4. Process. That is, the sound emitted from the seat speaker 4 is delivered directly to the user's ear, so that the effect of the sound appears most efficiently. When the predetermined distance is changed, the sound emitted from the seat speaker 4 is These processes are performed in order to avoid a decrease in the effect because the time until it reaches the user and the sound pressure of the sound change. Specifically, control signals for these processes are sent from the microcomputer 10 to the sound reproducing device 20.

  First, in S105, the sound pressure of the entire output sound output from the seat speaker 4 is adjusted according to the predetermined distance. Specifically, the predetermined distance is estimated based on the direction of the seat speaker 4 associated with the predetermined distance, and the sound pressure of the output sound is adjusted according to the predetermined distance. For example, in the state shown in FIG. 2, since the direction of the seat speaker 4 corresponding to the user B is directed upward from the direction of the seat speaker 4 corresponding to the user A, the predetermined distance Lb related to the user B is related to the user A. It can be seen that the distance is longer than the predetermined distance La. Therefore, in S105, the sound pressure of the output sound is adjusted so as to be proportional to the predetermined distances Lb and La. When the process of S105 ends, the process proceeds to S106.

  In S106, the reflection removal sound signal for forming the reflection removal sound emitted from the seat speaker 4 is corrected. Since this reflection removal sound signal is formed according to the head-related transfer function from the seat speaker 4 to the user's ear position, the head is based on the predetermined distance estimated according to the orientation adjustment of the seat speaker 4. The partial transfer function is set again, and the reflection removal sound signal is corrected based on the setting. When the process of S106 ends, the process proceeds to S107.

  In S107, the sound effect signal for the sound effect formation from the seat speaker 4 is corrected. When this sound effect is a sound effect given to the main sound output from a speaker other than the seat speaker 4, the timing at which the main sound and the sound effect reach the user's ear is important. That is, if this timing is shifted, the user may feel uncomfortable, so the phase of the sound effect signal is adjusted so that the timing is more appropriate, and the sound effect of the sound effect given to the user is appropriately adjusted. In order to obtain a state, the sound pressure of the sound effect is adjusted. After the process of S107, this control is terminated.

  According to this processing up to the above, since the orientation of the seat speaker 4 is adjusted according to the user's head position, the user is provided with voice that is not easily affected by the directivity of the seat speaker 4. This makes it possible to form a more comfortable acoustic space for each user regardless of the user's head position.

  In the vertical movement of the headrest 2 of the seat 1 shown in FIG. 1, the uppermost position corresponds to the user's height of 178 cm, and the lowermost position corresponds to the user's height of 144 cm. This is calculated from 2σ of the normal distribution of Japanese height. The vertical movement range of the headrest may be appropriately set based on the normal distribution of the height of the user belonging to the region or country where the speaker device according to the present invention is used.

<Modification>
Moreover, in the said Example, although the direction of the seat speaker 4 is controlled by the motor 5, you may make it interlock | cooperate mechanically with the up-and-down position of the headrest 2 and the direction of the seat speaker 4 instead. That is, by connecting the rotary shaft 8 for rotating the seat speaker 4 as shown in FIG. 1 and the mounting foot 2a of the headrest 2 with mechanical elements such as a worm gear and a pinion, The direction of the seat speaker 4 is uniquely associated. In this case, the reduction ratio of the mechanical elements and the like are sufficiently considered so that the seat speaker 4 faces the user's ear position corresponding to the vertical position of the headrest 2. Moreover, when adjusting the direction of the seat speaker 4 nonlinearly, a cam or the like may be used.

It is a figure which shows schematic structure of the speaker apparatus based on the Example of this invention. It is a figure which shows the state in which the direction of the seat speaker was changed in the speaker apparatus based on the Example of this invention. It is the flow which showed the flow of the speaker direction adjustment process performed in the speaker apparatus which concerns on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Seat 2 ... Headrest 3 ... Seat body 4 ... Seat speaker 5 ... Motor 6 ... Position sensor 10 ... Microcomputer 20 ... Audio playback device

Claims (10)

  Control means for controlling speaker adjusting means for adjusting the direction of the speaker provided on the seat based on the detection result of the position detecting means capable of detecting the position of the headrest capable of supporting the head of the user sitting on the seat A speaker control device. A speaker provided in the seat body and having a variable orientation;
Speaker orientation adjusting means for adjusting the orientation of the speaker;
Position detecting means for detecting the position of the headrest of the seat body,
Control means for controlling the speaker orientation adjusting means based on the detection result of the position detecting means;
A speaker device comprising: The seat body,
A speaker provided in the seat body and having a variable orientation;
A headrest provided on the seat body and capable of supporting a user's head;
Speaker orientation adjusting means for adjusting the orientation of the speaker;
Position detecting means for detecting the position of the headrest;
Control means for controlling the speaker orientation adjusting means based on the detection result of the position detecting means;
A speaker device comprising: Based on the position of the headrest detected by the position detection means, further comprising position estimation means for estimating the position of the user's ear,
The control means controls the direction of the speaker via the speaker direction adjusting means so that the speaker faces the user's ear position estimated by the position estimating means.
The speaker device according to claim 2 or 3. Sound pressure adjusting means for adjusting the output sound pressure of the speaker based on the distance from the speaker to the user's ear position when the direction of the speaker is controlled by the control means;
The speaker device according to any one of claims 2 to 4. When the direction of the speaker is controlled by the control means, among the audio signals supplied to the speaker, a predetermined audio signal related to the distance from the speaker to the user's ear position is used as the speaker and the user's ear position. Audio signal correction means for correcting based on the distance up to
The speaker device according to any one of claims 2 to 4. The predetermined audio signal is an audio signal for removing at least a part of a reflected sound generated by an output sound from another speaker different from the speaker, and the speaker provided in the seat body and a user's ear position A reflection-removed sound signal formed by a head-related transfer function according to the distance to
The speaker device according to claim 6, wherein the sound signal correction unit resets the head-related transfer function based on a distance between a speaker provided in the seat body and a user's ear position. The predetermined sound signal is a sound effect signal for giving a sound effect to output sound from another speaker different from the speaker,
The sound signal correcting means adjusts at least one of a portion related to a phase and a sound pressure of the sound effect signal based on a distance between a speaker provided in the seat body and a user's ear position. The speaker device according to 1.   When the position of the headrest is at the uppermost position, the control means directs the speaker so that the direction of the speaker is directed to a predetermined uppermost ear position that is an ear position of the user when the height of the user is 178 cm. The speaker device according to claim 2, wherein the speaker device is controlled.   When the position of the headrest is at the lowest position, the control means causes the speaker to face the predetermined lower ear position, which is the ear position of the user when the height of the user is 144 cm. The speaker device according to claim 2, wherein the direction of the speaker is controlled.

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