JP2000253481A - Loud speaker system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an influence of a peak dip generated by sound directly radiated in the air from a speaker unit and reflected sound by a wall surface. SOLUTION: Peak dip is generated by interference of each radiation sound of a woofer 1 and a tweeter 2 and reflected sound reflected after each of these radiation sounds once hits a wall surface. This peak dip is more often generated in a high frequency and becomes acoustically inconspicuous as a phase difference between the radiation sound and the reflected sound is smaller. Then, by getting the woofer 1 and the tweeter 2 closer to a wall surface 100 respectively, the phase difference between the radiation sound and the reflected sound is made smaller and an influence of the peak dip is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a loudspeaker system having a plurality of loudspeaker units, and more particularly to a loudspeaker system suitable for mounting on a flat surface such as a wall surface or a ceiling.

[0002]

2. Description of the Related Art As a speaker system having a plurality of speaker units as described above, for example, a two-way system as shown in FIG. 3 is conventionally known. As shown in the figure, this has a speaker unit for middle and low frequency sound, that is, a woofer 101, and a speaker unit for middle and high frequency sound, that is, a tweeter 102.
And the tweeter 102 are arranged in a plane on a surface (namely, a baffle plate) 104 of a substantially rectangular partition box (namely, enclosure) 103 for accommodating them, with their respective sound radiation surfaces exposed to the outside. I have.

[0003] This two-way speaker system is
For example, in a case where the woofer 101 and the tweeter 102 are used in a state where the woofer 101 and the tweeter 102 are arranged vertically in a row and each sound wave emitting surface is inclined obliquely downward as shown in FIG. Attach in the position. In this way, as shown in FIG. 4B, when this speaker system is viewed from the front side, the sound wave emitting area 101a of the woofer 101 and the sound wave emitting area 1 of the tweeter 102
02a overlap with each of these areas 101a and 102a.
In this case, it is possible to provide a high-quality sound balanced from a low range to a high range.

Of course, as shown in FIG. 5, the woofer 101 and the tweeter 102 may be arranged in a horizontal line. However, in this case, a time delay occurs in the left and right direction of the speaker system due to the difference in the distance between the sound paths from the woofer 101 and the tweeter 102. For this reason, the sound quality may be different depending on the listening position in the left-right direction.
In the vicinity of the crossover frequency between the woofer 101 and the tweeter 102, the polar pattern in the left-right direction may be different due to the sound path difference. In particular, when the speaker system is mounted on the wall surface 100 and used, a change in characteristics in the left-right direction is a serious problem. Therefore, in order to avoid such inconvenience, as shown in FIG.
It is desirable that 01 and the tweeter 102 be arranged in a vertical line.

As described above, when the sound wave emitting surfaces of the woofer 101 and the tweeter 102 are inclined with respect to the wall surface 100, the sound directly emitted from each sound wave emitting surface to the space and the wall surface 100 A so-called reflected sound that is reflected into the space after hitting the surface interferes with each other to generate a peak dip (phase interference). This will be described with reference to FIG.

That is, considering only the woofer 101, as shown in FIG.
The sound 101b directly radiated from the sound wave emitting surface of the object and the reflected sound 101c reflected once after hitting the wall surface 100
And are provided. In this case, the peak dip occurs at a frequency where the phase difference ΔT between the directly emitted sound 101b of the woofer 101 and the reflected sound 101c is a half wavelength (λ / 2). This is a straight line (dashed line) drawn horizontally from the sound wave emitting surface of the woofer 101 toward the wall surface 100,
The woofer 1 is located at a position where a straight line (two-dot chain line) obtained by extending the locus of the reflected sound 101c toward the wall surface 100 and intersecting with the straight line (two-dot chain line)
01 virtual image 101d, and the reflected sound 101c is radiated from this virtual image 101d. Then, the distance D between the actual sound wave emitting surface of the woofer 101 and the sound wave emitting surface of the virtual image 101d corresponds to the phase difference ΔT between the directly emitted sound 101b and the reflected sound 101c. Therefore, as the distance D increases, the phase difference ΔT between the directly emitted sound 101b and the reflected sound 101c increases, and the frequency at which a peak dip occurs decreases.

On the other hand, the tweeter 102 is also shown in FIG.
As shown in (b), a sound 102b directly radiated from the sound wave emitting surface and a reflected sound 102c reflected once after hitting the wall surface 100 are provided to the space. Also in this case, a straight line (dashed line) drawn horizontally from the sound wave emitting surface of the tweeter 102 toward the wall surface 100, and a straight line drawn by extending the locus of the reflected sound 102c toward the wall surface 100 (dotted chain line) ) And the tweeter 10
There are two virtual images 102d, and it can be considered equivalent to that the reflected sound 102c is emitted from this virtual image 102d. Note that, as described above, since the tweeter 102 and the woofer 101 are arranged on the common baffle plate 104 respectively, the distance between the sound wave emitting surface of the tweeter 102 and the wall surface 100 is apparent as shown in FIG. L is
It is larger than that of the woofer 101. Accordingly, the distance D between the actual sound wave emitting surface of the tweeter 102 and the sound wave emitting surface of the virtual image 102d, that is, the direct sound sound 102b and the reflected sound 1
The phase difference ΔT from the woofer 101 becomes larger than that of the woofer 101, and the peak dip occurs at a lower frequency.

[0008]

However, the sound has the property that the lower the frequency is, the lower the directivity is and the more the sound goes around. For this reason, in the low frequency band as described above, among the sounds radiated from the woofer 101 and the tweeter 102, the sound pressures of the reflected sounds 101c and 102c that are wrapped around and reflected on the wall surface 100 side are large. The sound pressure of the peak dip generated by the reflected sounds 101c and 102c and the direct radiated sounds 101b and 102b is also large. Therefore, according to the above-described related art, there is a problem that a peak dip is conspicuous in terms of hearing, which causes discomfort to a listener. This reduces the meaning of employing a two-way speaker system to provide listeners with high quality sound.

Accordingly, an object of the present invention is to realize a speaker system in which the peak dip is inconspicuous in terms of hearing.

[0010]

In order to achieve the above object, according to the present invention, in a speaker system having a plurality of speaker units, each of the speaker units is connected to a rear side thereof. The parts are arranged substantially in a row in a state of being close to a certain surface of the speaker system, for example, a mounting surface such as a wall surface or a ceiling, and the center axis of each speaker unit is aligned with the direction in which the speaker units are arranged. And at a plane substantially perpendicular to the mounting surface, forms an acute angle with the mounting surface, and extends in substantially the same direction along the plane.

For example, it is assumed that the speaker system according to the first aspect of the present invention is mounted on a wall surface. In this case, each speaker unit emits sound in an oblique direction that forms an acute angle with the wall surface. Some of these sounds once hit the wall and then reflect back into space. Therefore, in the space, the sound directly radiated from each speaker unit and the reflected sound reflected on the wall face interfere with each other, so that a peak dip occurs.

However, according to the first aspect of the present invention, each speaker unit is provided near the wall surface. Accordingly, the phase difference between the sound directly radiated from each speaker unit to the space and the reflected sound is small, and accordingly, the frequency at which the peak dip occurs is increased accordingly.

When the speaker system according to the first aspect of the present invention is viewed from a direction substantially perpendicular to a wall surface,
Each speaker unit emits sound in a direction along each row and in substantially the same direction. Therefore, when the speaker system according to the first aspect of the present invention is viewed from a direction substantially perpendicular to the wall surface, each sound wave emission region of each speaker unit overlaps. The radiated sound can be heard in a well-balanced manner. The same applies to the case where the speaker system is mounted on the ceiling.

According to a second aspect of the present invention, in the speaker system according to the first aspect of the present invention, the position of each of the speaker units with respect to the one surface is fixed.

According to the second aspect of the present invention, the mutual positional relationship between each speaker unit and the above-mentioned certain surface, for example, a mounting surface with a wall surface or the like is fixed. Therefore,
When the speaker system according to the second aspect of the present invention is mounted on a wall surface or the like, the arrangement direction of the speaker units, that is, the direction of each speaker unit when the speaker system is viewed from a direction perpendicular to the wall surface or the like. Optionally, the same operation as that of the first aspect can be achieved. Therefore, the radiation direction of each speaker unit when viewed from the above direction can be arbitrarily set.

According to a third aspect of the present invention, in the speaker system according to the first aspect of the present invention, each of the speaker units is placed in a state where the radiation sound of each speaker unit does not interfere with the main body of another speaker unit. They are arranged at intervals.

That is, when the speaker system according to the third aspect of the invention is viewed from the direction along the wall surface and perpendicular to the direction in which the speaker units are arranged, each speaker unit is positioned with respect to the wall surface. It emits sound in a direction that forms an acute angle and in substantially the same direction. Therefore, if the spacing between the speaker units is too small, the radiated sound of each speaker unit interferes with the main body of another speaker unit, and its propagation path is interrupted. Therefore, in the invention according to claim 3, by arranging each speaker unit at an interval, the radiated sound of each loudspeaker unit does not interfere with the main body of another loudspeaker unit. Propagation paths can be secured.

According to a fourth aspect of the present invention, in the speaker system according to the third aspect of the present invention, each of the speaker units has a different external dimension, and the center axis of any of the speaker units is set at the center axis. Forming an acute angle with one surface of the speaker unit,
That is, the speaker units are arranged in the order of the outer dimensions, with the speaker units having smaller external dimensions than the arbitrary speaker unit being arranged on the side where the sound wave emitting surface side is inclined.

The difference in the external dimensions of each speaker unit here means, for example, a sound wave radiation surface caused by using a woofer, a tweeter, or a squawker (medium sound speaker unit) as each speaker unit. Refers to the difference in external dimensions.

For example, it is now assumed that another speaker unit having a larger outer dimension than the arbitrary speaker unit is arranged on the side of the arbitrary sound wave emitting surface of the arbitrary speaker unit. In this case, an obstacle called the other speaker unit having an outer dimension larger than that of the arbitrary speaker unit exists in front of the sound wave emitting surface of the arbitrary speaker unit. Therefore, in order to prevent the radiated sound of an arbitrary speaker unit from interfering with the main body of the other speaker unit, it is necessary to provide a large space between these speaker units, and accordingly, the entire speaker system becomes large. Become

On the other hand, as in the invention according to the fourth aspect, another speaker unit having a smaller external dimension than the arbitrary speaker unit is provided on the side where the sound wave emitting surface of the arbitrary speaker unit is inclined. Is arranged, the obstacle obstructing the sound wave emitting surface of an arbitrary speaker unit can be reduced. Therefore, the interval between the speaker units can be narrowed as compared with the above, and the whole speaker system can be downsized accordingly.

According to a fifth aspect of the present invention, in the loudspeaker system according to the first aspect of the present invention, the certain aspect includes:
At right angles to a plane that is substantially parallel to the vertical plane that passes through the listening direction,
The respective speaker units are arranged on a plane orthogonal to the certain plane.

For example, it is assumed that the speaker system according to the present invention is mounted on a wall surface. In this case, the speaker system is mounted with the above-mentioned one surface, for example, the mounting surface along the wall surface, and the speaker units arranged in the vertical direction. Thereby, when the speaker system according to claim 5 is viewed from the front side, the sound wave radiation areas of the speaker units overlap,
The radiated sound of each speaker unit can be heard in a well-balanced manner.

On the other hand, it is assumed that the speaker system according to the present invention is mounted on, for example, a ceiling surface. In this case, the speaker system is mounted with the mounting surface thereof along the ceiling surface and the speaker units arranged side by side on a plane substantially parallel to a vertical plane passing in the listening direction. Therefore, when the speaker system according to the fifth aspect is viewed from the front side (the side facing the ceiling surface), the sound wave radiation areas of the speaker units overlap, and the radiated sound of each speaker unit is heard in a well-balanced manner. can do.

Further, it is assumed that the speaker system according to the present invention is mounted on, for example, a floor. In this case, the speaker system has its mounting surface along the floor surface,
The speaker units are mounted in a state where the speaker units are arranged on a plane substantially parallel to a vertical plane passing through the listening direction. Therefore,
When the speaker system according to claim 5 is viewed from the front side (the side facing the floor surface), the sound emission areas of the speaker units overlap, and the radiated sound of each speaker unit is heard in a well-balanced manner. Can be.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a speaker system according to the present invention will be described with reference to FIGS.

FIG. 1 shows a schematic configuration of the present embodiment. As shown in the figure, the speaker system of the present embodiment
For example, it is a two-way type having a cone-shaped woofer 1 and a dome-shaped tweeter 2, for example. The woofer 1 and the tweeter 2 are composed of a substantially disk-shaped base portion 3 and a substantially dome-shaped cover portion 4 covering one surface of the base portion 3.
And is housed in an enclosure 5 comprising:

The base portion 3 is fixed to the wall surface 100 by a screw (not shown) via a substantially disk-shaped fixture 6 with the other surface side facing the wall surface 100. Three screw holes 31 are provided in the peripheral portion of the base portion 3, respectively.
31 and 31 are provided at equal intervals.

On the other hand, three through holes 41, 41, 41 facing the screw holes 31, 31, 31 of the base portion 3 are also provided in the peripheral portion of the cover portion 4. The cover 4 and the base 3 are connected by screwing screws (not shown) into the screw holes 31, 31, 31 via the holes 41, 41, 41. The woofer 1 and the tweeter 2 are fixed to the inside of the cover portion 4. By connecting the cover portion 4 to the base portion 3, the woofer 1 and the tweeter 2 are respectively connected as follows. A good positional relationship.

That is, the woofer 1 and the tweeter 2 have their respective rear sides (the sides opposite to the sound wave emitting surface) on the base 3.
, In other words, in a state of being close to the wall surface 100, for example, are arranged in a vertical line. At the same time, the woofer 1 and the tweeter 2 form an acute angle θ between the center axes 11 and 21 with the wall surface 100 in a plane along the respective arrangement direction (vertical direction) and substantially perpendicular to the wall surface 100. And extending obliquely with respect to the wall surface 100 so as to extend in the same direction along the plane. The surface (the other surface) of the base portion 3 on the side in contact with the wall surface 100 corresponds to a certain surface described in the claims. In the present embodiment, the inclination angle θ is defined as θ =
40 degrees.

Therefore, according to the loudspeaker system of this embodiment, when viewed from the front as shown in FIG. 1A, the woofer 1 and the tweeter 2 radiate sound downward respectively. I do. Therefore, in this direction, the middle and low range sound radiated from the woofer 1 and the middle and high range sound radiated from the tweeter 2 can be heard in a well-balanced manner.

On the other hand, when the loudspeaker system of the present embodiment is viewed from the side as shown in FIG. Emits sound towards. Here, if the arrangement interval S between the woofer 1 and the tweeter 2 is too small, the radiated sound of the woofer 1 interferes with the main body of the tweeter 2 or a housing related thereto, and the propagation path thereof is blocked. Therefore, in the present embodiment, the interval S between the woofer 1 and the tweeter 2 is set sufficiently large such that the propagation path of the radiated sound of the woofer 1 is not interrupted by the tweeter 2 body or the like.

Further, in the present embodiment, the woofer 1 having a large outer dimension is disposed behind the tweeter 2 having a smaller outer dimension than the woofer 1. Here, if the tweeter 2 is arranged behind the woofer 1, the propagation path of the radiated sound of the tweeter 2 is largely blocked by the woofer 1 main body. To avoid this, it is necessary to increase the distance S between the woofer 1 and the tweeter 2. In this case,
The whole speaker system becomes large. On the other hand, if the woofer 1 is disposed behind the tweeter 2 as in the present embodiment, the tweeter 2 having a small external dimension does not become an excessively large obstacle for the woofer 1. Therefore, the distance S between the woofer 1 and the tweeter 2 can be reduced, and the entire speaker system can be reduced in size accordingly.

By arranging the woofer 1 and the tweeter 2 so as to be shifted in the front-rear direction, the wavefronts of the sound waves radiated from the woofer 1 and the tweeter 2 are shifted. In such a case, if the electroacoustic signal supplied to the tweeter 2 located ahead of the woofer 1 is delayed by a time corresponding to the interval S between the woofer 1 and the tweeter, the wavefronts of the radiated sounds can be aligned. .

In order to realize the positional relationship between the woofer 1 and the tweeter 2 as described above, the cover portion 4 is provided with a concave portion 42 depressed inside the cover portion 4. The woofer 1 and the tweeter 2 are fixed respectively. Then, in order to expose the respective sound wave emitting surfaces of the woofer 1 and the tweeter 2 to the outside, the size of each sound wave emitting surface of the woofer 1 and the tweeter 2, that is, the size corresponding to each aperture is provided in the recess 42. Circular through holes 43 and 44 are provided.

Although not shown, the base portion 3 is provided with a through hole penetrating from one surface side to the other surface side. Then, an amplifier (not shown) and the like to the woofer 1 and the tweeter 2 through the through-hole, the through-hole 61 provided substantially in the center of the above-described fixture 6, and the through-hole 110 provided in the wall surface 100. A line (not shown) for supplying an electroacoustic signal is wired. In FIG. 1B, a substantially semicircular dotted line 7 provided so as to cover the entire cover 4 is a punching net for protecting the speaker system including the woofer 1 and the tweeter 2. It is.

By the way, also in the speaker system of the present embodiment, the sound radiated directly from the woofer 1 and the tweeter 2 into the space and the reflected sound which once hits the wall surface 100 and is reflected into the space interfere with each other. By doing
The peak dip described above occurs. This will be described with reference to FIG.

For example, consider only the woofer 1 now. In this case, as shown in FIG. 2A, a sound 1a radiated directly from the woofer 1 and a reflected sound 1b reflected once after hitting the wall surface 100 are provided in the space. Then, at this time, the peak dip occurs at a frequency where the phase difference ΔT between the directly radiated sound 1a of the woofer 1 and the reflected sound 1b is a half wavelength (λ / 2). This is similar to the case of FIG. 6 described above, in which a straight line (dashed-dotted line) drawn horizontally from the sound wave emitting surface of the woofer 1 toward the wall surface 100 and the locus of the reflected sound 1b are extended to the wall surface 100 side. A virtual image 1c of the woofer 1 exists at a position where the drawn straight line (two-dot chain line) intersects, and it can be considered as equivalent to the reflected image 1b emitted from the virtual image 1c.
Then, the distance D between the actual sound wave emitting surface of the woofer 1 and the sound wave emitting surface of the virtual image 1c thereof corresponds to the phase difference ΔT between the directly emitted sound 1a and the reflected sound 1b.

Here, in the present embodiment, the woofer 1 is provided close to the wall surface 100 (for example, when the diameter of the woofer 1 is about 92 mm, the sound wave radiating surface of the woofer 1 and the wall surface 100 are separated from each other). Is set to be very short, that is, L 、 65 mm.) As is apparent from FIG.
The distance D becomes very short. Therefore, the frequency at which the peak dip occurs is higher than in the case of the above-described prior art. In such a high frequency band, the woofer 1
The sound pressure of the reflected sound 1b that is reflected around the wall 100 among the sounds radiated from the
And the sound pressure of the peak dip generated by the direct radiation sound a is also small. Therefore, by increasing the frequency at which the peak dip occurs as described above, the peak dip can be made inconspicuous in the sense of hearing, and it is possible to prevent the listener from feeling uncomfortable.

On the other hand, the tweeter 2 is also shown in FIG.
As shown in (2), the sound 2a radiated directly from the sound wave emitting surface to the space and the reflected sound 2b reflected once after hitting the wall surface 100 are provided to the space. Then, similarly to the above, a straight line (dash-dot line) drawn horizontally from the sound wave emitting surface of the tweeter 2 toward the wall surface 100 and the reflected sound 2b
Is a virtual image 102c of the tweeter 2 at the position where a straight line (two-dot chain line) obtained by extending the locus of
And the reflected sound 2b is radiated from the virtual image 2c.

Of course, the tweeter 2 is also provided close to the wall surface 100 (for example, the tweeter 2 has a diameter of about 23 m).
m, the sound emission surface of the tweeter 2 and the wall surface 10
The distance L to 0 is set very short, L ≒ 34 mm. ), The distance D between the tweeter 2 and the virtual sound image 2c between the sound wave emitting surfaces becomes very short. Therefore, the frequency of the peak dip generated by the radiated sound of the tweeter 2 is also increased, and this peak dip can be prevented from being noticeable in audibility.

The woofer 1 and the tweeter 2 are fixed to the base 3 via the cover 4 respectively. Therefore, when the base unit 3 is mounted on the wall surface 100 via the mounting fixture 6, the woofer 1 and the tweeter 2 when the speaker system of the present embodiment is viewed from the front, that is, the direction in which the woofer 1 and the tweeter 2 are arranged. The above-described effects can be obtained even if the direction is arbitrary. Therefore, the radiation direction of the sound from the woofer 1 and the tweeter 2 when viewed from the front can be arbitrarily set without worrying about the above-mentioned problem in the related art.

In this embodiment, the case where the speaker system is mounted on the wall surface 100 has been described.
For example, it may be provided on a ceiling or the like other than the wall surface 100. Also,
Although the two-way speaker system having the woofer 1 and the tweeter 2 has been described, the present invention is not limited to this, and the present invention can be applied to a three-way speaker system having a squawker. Then, the woofer 1 and the tweeter 2
Although cone-shaped and dome-shaped speaker units are used, other types may be used. Further, the inclination angle θ between the woofer 1 and the tweeter 2 with respect to the wall surface 100 is set to θ = 40 degrees, but any other angle may be used as long as it is an acute angle.

Further, when the speaker system of the present embodiment is mounted on the wall surface 100, the base portion 3 is mounted on the wall surface 100 (via the mounting fixture 6). However, the present invention is not limited to this. For example, the cover 4 may be directly attached to the wall surface 100 without providing the base 3 (and the attachment 6). In this case, instead of the base part 3,
The wall surface 100 forms a part (back surface) of the enclosure 5, and this part corresponds to a certain surface described in the claims.

[0045]

As described above, according to the present invention, the frequency of the peak dip generated by the interference between the sound directly radiated from each speaker unit to the space and the reflected sound reflected on the wall or the like. Can be higher. In such a high frequency band, since the sound pressure of the above-mentioned reflected sound which is sneak-forwarded from each speaker unit to a wall surface or the like is small, the sound pressure of the peak dip is also small. Therefore, there is an effect that the peak dip can be prevented from being noticeable in terms of hearing. When, for example, a woofer and a tweeter, or a woofer, a squawker and a tweeter are used as the speaker units, the performance of each speaker unit can be sufficiently exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention;
(A) is a front view, (b) is an AA end view in (a).

FIGS. 2A and 2B are diagrams illustrating a sound propagation path of each speaker unit according to the embodiment, in which FIG. 2A is a diagram illustrating a woofer and FIG. 2B is a diagram illustrating a tweeter.

3A and 3B are schematic configuration diagrams of a conventional two-way speaker system, in which FIG. 3A is a perspective view and FIG. 3B is a vertical center end view.

4A and 4B are diagrams showing a state in which the two-way speaker system of FIG. 3 is attached to a wall surface, wherein FIG. 4A is a diagram viewed from a side, and FIG.

FIG. 5 is a front view showing a state where the speaker system is mounted on a wall surface in a form different from that of FIG. 4;

6A and 6B are diagrams showing a sound propagation path of each speaker unit in FIG. 5, where FIG. 6A is a diagram showing a woofer and FIG.
Is a diagram of a tweeter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Woofer 2 Tweeter 3 Base part 11, 21 Central axis 100 Wall surface

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ken Iwayama 7-2-1, Minatojima-Nakamachi, Chuo-ku, Kobe-shi, Hyogo F-term in TOA Corporation (reference) 5D018 AD14 AD27

Claims (5)

[Claims] 1. A speaker system having a plurality of speaker units, wherein each of the speaker units is arranged in a row substantially in a state in which a rear side of each of the speaker units is close to a certain surface of the speaker system. In a plane in which the respective central axes of the units are arranged along the direction in which the speaker units are arranged and are substantially perpendicular to the certain surface, they form an acute angle with the certain surface and extend in substantially the same direction along the plane. A speaker system provided in an extended state. 2. The speaker system according to claim 1, wherein a position of each of the speaker units with respect to the one surface is fixed. 3. A state in which the radiated sound of each speaker unit does not interfere with the main body of another speaker unit.
The speaker system according to claim 1, wherein each of the speaker units is arranged at an interval. 4. The speaker unit according to claim 1, wherein each of the speaker units has a different outer dimension, and a center axis of the arbitrary speaker unit forms an acute angle with the certain surface so that a front portion side of the arbitrary speaker unit is biased. 4. The speaker system according to claim 3, wherein each of the speaker units is arranged in the order of the outer dimensions in a state where a speaker unit having an outer dimension smaller than the arbitrary speaker unit is arranged. 5. The apparatus according to claim 1, wherein the certain surface is orthogonal to a surface substantially parallel to a vertical plane passing through the listening direction, and the speaker units are arranged on a surface orthogonal to the certain surface. Speaker system.