TECHNICAL FIELD
[0001] The present invention relates to a speaker device configured to cause a sound to
be reflected off a wall surface of a room and propagate.
BACKGROUND ART
[0002] There is conventionally a speaker device including: an elongated housing shaped like
a quadrangular prism and standing upright; and a plurality of speaker units provided
on all respective four side surfaces of the housing (see Patent Document 1, for example).
This speaker device delays and adjusts the timing at which each of the speaker units
outputs an audio signal, to output a sound beam as a sound wave with directivity.
This speaker device outputs the sound beams toward a floor and a ceiling of a room
to cause the sound beams to be reflected a plurality of times, and accordingly indirect
sounds reach a listener from many directions. This configuration achieves an effect
in which the listener does not feel an accurate position of the speaker device. Speaker
devices described below are known as conventional speaker devices.
[0003] Document
CN 201518537 U discloses a broadly-radiated sound field three-frequency-division stereo loudspeaker
which comprises a rectangular case body. A basetone loudspeaker is arranged on the
right half side on the front side of the case body, two high pitch loudspeakers are
arranged on the left half side on the front side of the case body, a mid-frequency
loudspeaker is arranged on the right half side on the top surface of the case body,
and two top high pitch loudspeakers are arranged on the left half side on the top
surface of the case body; the loudspeakers on the case body are connected through
a three-division frequency divider and an audio input bus. The sound field generated
by the loudspeaker can be broad, the sound and the sound pressure can be distributed
uniformly.
[0004] Document
DE 3201455 A1 discloses: A loudspeaker box having at least one bass loudspeaker which is arranged
in the front panel in an enclosure with resonance space and radiates towards the front,
a medium-range loudspeaker and a high-range loudspeaker, characterised in that the
basic body which forms the enclosure for the bass loudspeaker is constructed to be
pentagonal in cross-section, that furthermore a first middle-range loudspeaker is
arranged in one of the rear plates which are set to be inclined towards the rear with
respect to the front plate, and that above the resonance space formed in the basic
body, two high-range loudspeakers are arranged in such a manner that the axes of their
radiation are directed parallel to the front plate and oppositely to one another inclined
towards the top, and that above the resonance space provided in the basic body, a
second middle-range loudspeaker is furthermore arranged in such a manner that the
axis of its radiation is directed perpendicularly to the front plate and inclined
towards the top.
PRIOR ART DOCUMENTS
PATENT DOCUMENTS
[0005]
Patent Document 1: Japanese Patent Application Publication No. 2007-37058
Patent Document 2: Japanese Patent Application Publication No. 11-055780
SUMMARY OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0006] In the case where the speaker device disclosed in Patent Document 1 is placed in,
e.g., a corner of a room, and a sound is emitted from a speaker unit facing walls
of the corner, the emitted sound becomes unclear because the sound is muffled in the
middle frequency range in the corner of the room. Also, the plurality of speaker units
are as described above provided on all the respective four side surfaces of the housing
in the speaker device disclosed in Patent Document 1. Thus, the side surfaces cannot
be decorated, thereby limiting a design of the housing.
[0007] Therefore, the object of the present invention is to provide a speaker device with
sound clarity which is maintained even when a sound is reflected off a wall surface
and with high flexibility in design of a housing.
MEANS FOR SOLVING PROBLEM
[0009] A speaker device according to the present invention includes the features of claim
1.
[0010] The speaker device according to the present invention is placed near a wall of a
room, for example. A sound emitted from the first speaker unit provided near the back
surface is reflected off a wall surface so as to propagate to the room. Even if some
frequencies of the emitted sound are attenuated by the reflection, and thereby the
sound is muffled, the frequencies can be compensated by the second speaker unit oriented
upward.
[0011] As another form of the present invention, the speaker device may further include
a reflector disposed on an upper side of the at least one second speaker unit and
configured to reflect a sound emitted from the at least one second speaker unit, toward
a front side of the housing.
[0012] The electronic circuit is configured to supply, to the at least one second speaker
unit, a signal in frequencies of a middle frequency range of the frequency range of
the sound signal.
[0013] The housing may be divided into a plurality of layers at least including: an upper
layer box having the opening of the upper surface and accommodating the at least one
second speaker unit; a middle layer box having the opening of the back surface and
accommodating the at least one first speaker unit; and a lower layer box accommodating
the electronic circuit.
[0014] The speaker device may be configured such that the at least one first speaker unit
includes a plurality of speaker units to each of which a sound signal of corresponding
at least one of a plurality of channels is to be supplied, and the electronic circuit
is configured to supply, to the at least one second speaker unit, a signal obtained
by extracting the partial signal from the sound signal in each of the plurality of
channels and synthesizing the extracted signals.
[0015] The speaker device according to the present invention further includes: a first filter
configured to take at least a signal in frequencies of a middle frequency range containing
a human voice, out of an audible frequency range of the sound signal; and a second
filter configured to take a signal in frequencies of each of a low frequency range
and a high frequency range, out of the audible frequency range of the sound signal,
wherein the signal in the frequencies of each of the low frequency range and the high
frequency range is different from the signal in the frequencies of the middle frequency
range, wherein the signal output from the first filter is output to the at least one
second speaker unit, and wherein the signal output from the second filter is output
to the at least one first speaker unit.
[0016] The speaker device may be configured such that the at least one second speaker unit
is a middle-frequency-range speaker with a reduced sound emission characteristic of
the low frequency range, and the first filter is a low-pass filter configured to take
a signal in frequencies of a frequency range which is less than or equal to the middle
frequency range, and the frequencies of the frequency range which is less than or
equal to the middle frequency range contains frequencies of the low frequency range.
[0017] The speaker device may be configured such that the sound signal is a stereo signal
in right and left channels, each of right and left first speaker units as the at least
one first speaker unit is configured such that a signal in a corresponding one of
the left and right channels is input to said each of right and left first speaker
units, and a signal obtained by synthesizing the right and left channels is input
to one second speaker unit as the at least one second speaker unit.
EFFECT OF THE INVENTION
[0018] According to the present invention, it is possible to achieve clarity of emitted
sounds even in the case where no speaker unit is provided on the front surface to
increase flexibility in design of the housing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
Figs. 1(A) through 1(C) are external views of a speaker device according to a first
embodiment of the present invention.
Fig. 2 is a view illustrating an internal structure of the speaker device.
Fig. 3 is a rear view of the speaker device, with a speaker grille removed.
Fig. 4 is a perspective view of a head piece provided on an upper end of the speaker
device.
Fig. 5 is a plan view illustrating an example of an installation position of the speaker
device.
Fig. 6 is a block diagram illustrating an electronic circuit of the speaker device.
Fig. 7 is a block diagram illustrating a speaker device according to a second embodiment
of the present invention.
Figs. 8(A) and 8(B) are views illustrating characteristics of filters provided on
the speaker device according to the second embodiment.
Fig. 9 is an external view of the speaker device according to the second embodiment
in a stereo configuration.
Fig. 10 is a view illustrating a structure of a speaker device according to a third
embodiment of the present invention.
Fig. 11 is a block diagram illustrating the speaker device according to the third
embodiment.
Fig. 12(A) through 12(C) are external views of the speaker device according to the
third embodiment of the present invention.
Fig. 13 is a view illustrating an example of an installation position of a speaker
device according to a fourth embodiment.
Fig. 14 is a block diagram illustrating an electronic circuit of the speaker device
according to the fourth embodiment.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0020] Hereinafter, there will be described speaker devices according to embodiments of
the present invention by reference to the drawings. Figs. 1(A)-1(C) are external views
of a speaker device according to an embodiment of the present invention. Fig. 1(A)
is a front elevational view of the speaker device, Fig. 1(B) is a right side view
thereof, and Fig. 1(C) is a rear view thereof. Fig. 2 is a view illustrating an internal
structure of the speaker device. Fig. 3 is a rear view of the speaker device, with
a speaker grille removed.
[0021] A speaker device 1 according to the embodiment of the present invention includes:
a housing 11 for accommodating a plurality of speakers; a base 14 shaped like a round
board and provided on a floor surface to support the housing 11; and a pillow 13 shaped
like a rod and connecting the housing 11 and the base 14 to each other. The housing
11 is supported by the pillow 13 and the base 14 and provided upright in a vertical
direction.
[0022] The housing 11 is shaped like a substantially quadrangular prism which slightly tapers
in width toward an upper end thereof. That is, the housing 11 has a quadrangular-pyramidal
trapezoid shape (a shape obtained by horizontally cutting out a vertex portion or
a head portion from a quadrangular pyramid in a plane parallel with a bottom surface
of the pyramid), accurately. The angle of inclination of a side surface of the housing
11 with respect to the vertical line is 2%. The speaker device 1 is installed in a
state in which an edge line portion 19 interposed between two side surfaces of the
speaker device 1 is located on a front side (a user side). In the following explanation,
the front direction of the speaker device is referred to as a front direction, and
the back direction is referred to as a rear direction. Also, a right and left direction
is defined based on a state in which the speaker device 1 is viewed from a user located
on a front side.
[0023] In this speaker device 1, the speaker units are oriented not in the front direction
but in the rear direction. Thus, as illustrated in Figs. 1 (B) and 1 (C), a speaker
grille 12 is provided on a back portion of the housing 11. As a result, the speaker
grille 12 need not be provided on a front portion of the speaker device 1, and decorative
LEDs 16 are provided on the edge line portion 19 of the front surface of the housing
11.
[0024] The interior of the housing 11 is divided by two partition plates into three spaces
in the up and down direction. The three spaces include: an upper space as a middle-frequency-range
speaker box 30 for accommodating a speaker unit 20; a central space as a stereo speaker
box 31 for accommodating speaker units 21, 22; and a lower space as a circuit box
32 for accommodating an electronic circuit 15.
[0025] As illustrated in Figs. 2 and 3, the stereo speaker box 31 is open in its back surface,
and a baffle board 24 is provided in this opening. This baffle board 24 is not flat
but curved in the right and left direction so as to match the quadrangular prism shape
of the housing 11. The speaker units 21, 22 are mounted on the baffle board 24, and
a bass reflex port 23 is formed in the baffle board 24. The speaker unit 21 is a speaker
unit for a right channel and mounted so as to be oriented in an obliquely right and
rear direction. The speaker unit 22 is a speaker unit for a left channel and mounted
so as to be oriented in an obliquely left and rear direction. The bass reflex port
23 is formed so as to communicate with the interior of the stereo speaker box 31 via
a duct. The baffle board 24 is covered with the speaker grille 12. As illustrated
in Fig. 1(B), the speaker grille 12 is formed of a metal mesh and is substantially
flush with the housing 11.
[0026] An upper surface of the speaker box 30 for a middle frequency range has an opening
in which the speaker unit 20 is mounted so as to be oriented upward. A head piece
10 is provided on the upper side of the speaker unit 20 such that sounds emitted from
the speaker unit 20 are reflected off the head piece 10 in the front direction.
[0027] Fig. 4 is a perspective view of the head piece. The head piece 10 includes: a main
body 101, as an upper portion, having a sound emission opening 110; a top board 102
disposed on an upper surface of the main body 101; and a skirt 106 as a lower portion.
The main body 101 is shaped substantially like a cube. A bottom board 103 of the head
piece 10 has a round opening 103A at its central portion. The diameter of the opening
103A is substantially equal to that of the speaker unit 20.
[0028] A reflector 105 (105A, 105B) is formed in the main body 101. This reflector 105 is
constituted by two triangle surfaces each connecting between (a) a vertex 105C located
at a lower end of sides interposed between two side surfaces 113, 114 serving as a
back board 104 and (b) a corresponding one of upper sides of two side surfaces 111,
112 serving as the cutout or the sound emission opening 110. Since the main body 101
is shaped substantially like a cube, each of the left and right surfaces 105A, 105B
of the reflector 105 forms an angle of about 45 degrees with respect to a horizontal
plane such as the bottom board 103.
[0029] A sound emitting surface of the speaker unit 20 is disposed under the head piece
10 so as to be oriented upward vertically while sharing the central axis with the
head piece 10. Also, each surface of the reflector 105 of the head piece 10 faces
the sound emitting surface of the speaker unit 20, and the angle of inclination of
each surface of the reflector 105 is about 45 degrees. Thus, as indicated by arrows
201 in Fig. 4, a sound emitted upward from the speaker unit 20 is reflected off the
reflector 105 and propagates so as to spread in front right and left directions. With
this construction, even when the sound is emitted upward from the speaker unit 20,
the sound can be reflected off the reflector 105 and propagate so as to spread in
the front right and left directions from front portions of the side surfaces of the
housing 11 with little loss.
[0030] Fig. 5 is a plan view illustrating an example of an installation position of the
speaker device 1. The speaker device 1 is installed at, e.g., a corner of a room in
a state in which a back portion of the speaker device 1 faces a wall. Since the LEDs
16 are provided decoratively on the front portion of the speaker device 1 without
the speaker units and the speaker grille, the speaker device 1 functions also as a
decorative interior unlike common speaker devices.
[0031] When a sound signal is input to the speaker device 1, sounds are emitted from the
speaker units 22, 21 for the respective left and right channels. Since the speaker
units 21, 22 are oriented in the back direction (i.e., so as to face the wall), the
sounds emitted from the speaker units 21, 22 for the respective left and right channels
are reflected off a wall surface and propagate in the front direction (i.e., toward
a central portion of the room). Sounds in a high frequency range among the sounds
emitted from the speaker units 21, 22 travel straight when compared to sounds in the
other frequency ranges, and accordingly the sounds emitted from the speaker units
21, 22 are well reflected off the wall. Since sounds in a low frequency range are
emitted with a small amount of spatial impression in audibility, even when the user
listens to the sounds as if the sounds are made near the wall surface, the user (the
listener) feels little discomfort. In contrast, a middle frequency range contains
human speaking voices and human singing voices, and when sounds in the middle frequency
range are reflected off the wall surface, the sounds are attenuated greatly and thereby
muffled, resulting in lowered clarity. To solve this problem, the speaker device 1
extracts components of the middle frequency range from sounds in the left and right
channels and emits sounds in the middle frequency range from the speaker unit 20.
Although the speaker unit 20 is oriented upward, the emitted sounds in the middle
frequency range are well propagated frontward by the head piece 10 provided on the
upper side of the speaker unit 20. As a result, the user can clearly listen to the
sounds in the low through high frequency ranges without discomfort.
[0032] The electronic circuit 15 is disposed in the circuit box 32 of the housing 11. Fig.
6 is a block diagram illustrating a main portion of the electronic circuit 15. The
electronic circuit 15 includes a controller 50, a signal processor 51, an audio amplifier
52, an input selector 53, a Bluetooth (registered trademark) communication circuit
54, a cable connector 55, and an LED lighting circuit 56.
[0033] The controller 50 is constituted by a microcomputer. A light receiving circuit 40
is connected to the controller 50, and this light receiving circuit 40 receives an
infrared signal transmitted from an infrared remote control, not shown. The light
receiving circuit 40 converts the received infrared signal to an electronic signal
and inputs it to the controller 50. Based on the signals received from the light receiving
circuit 40, the controller 50 selects an input signal in the input selector 53, adjusts
sound quality in the signal processor 51, adjusts a sound volume in the audio amplifier
52, turns on and off the Bluetooth communication circuit 54, sets a password, and
controls illumination of the LEDs 16, for example.
[0034] The signal processor 51 adjusts sound quality of an audio signal (a two-channel stereo
signal) input from the input selector 53. Also, the signal processor 51 extracts components
in the middle frequency range, from signals in the right and left channels, and synthesizes
the extracted components to output the obtained signal as an audio signal in a third
channel. That is, the signal processor 51 functionally includes band-pass filters
66, 67 and a mixer 68. The audio amplifier 52 functionally includes amplifier circuits
64, 65, 69 for three channels which respectively amplify audio signals in the left
channel, the right channel, and the middle frequency range. The amplifier circuit
64 amplifies a sound signal in the left channel to output it to the speaker 22. The
amplifier circuit 65 amplifies a sound signal in the right channel to output it to
the speaker 21.
[0035] The band-pass filter 66 extracts sound signals in the middle frequency range (e.g.,
from 100 Hz to 7 kHz) from those in the left channel to output the extracted signals
to the mixer 68. Likewise, the band-pass filter 67 extracts sound signals in the middle
frequency range from those in the right channel to output the extracted signals to
the mixer 68. The mixer 68 synthesizes the input sound signals in the middle frequency
range in the left channel and the input sound signals in the middle frequency range
in the right channel to output the synthesized signals to the amplifier 69. The amplifier
69 amplifies the synthesized signals in the middle frequency range to output them
to the speaker unit 20. Accordingly, the speaker unit 20 emits the sounds in the middle
frequency range in the left and right channels.
[0036] As illustrated in Fig. 5, in the case where the speaker device 1 is placed in a state
in which its back surface faces the wall of the room, the sounds emitted from the
speaker units 21, 22 are reflected off the wall surface. As a result, even the sounds
emitted from the slim housing echo with spatial impression. Even if the sounds in
the middle frequency range become unclear at this emission due to reflection against
the wall surface, the sounds in the middle frequency range are emitted from the speaker
unit 20, the sounds in the left and right channels echo clearly in all the frequency
ranges.
[0037] Also, no speaker unit or no speaker grille is provided on the front surface of the
housing 11, resulting in increase in flexibility in design for the front surface.
[0038] The middle frequency range to be extracted by the band-pass filter 66 is a frequency
range which generally ranges from 100 Hz to 7 kHz, but the middle frequency range
is not limited to this frequency range. The middle frequency range may be a portion
of the frequency range which ranges from 100 Hz to 7 kHz.
[0039] While the speaker units 21, 22 provided on the back surface emit sounds in all the
frequency ranges in the present embodiment, the speaker units 21, 22 can emit sounds
based on signals from which frequency range components to be emitted from the speaker
unit 20 oriented upward are removed.
[0040] While the two speaker units 21, 22 are provided on the back surface in the above-described
embodiment, the number of speaker units is not limited to two. Also, the number of
channels of sounds to be emitted is not limited to two channels and may be a single
channel (mono), for example.
[0041] It is noted that the shape of the housing 11 of the speaker device 1 is not limited
to the quadrangular-pyramidal trapezoid shape and may be a column shape such as a
conical trapezoid shape, a circular cylindrical shape, and a prism shape.
[0042] Each of the speaker units 21, 22 corresponds to a first speaker unit. The speaker
unit 20 corresponds to a second speaker unit.
[0043] There will be next explained second through fourth embodiments. It is noted that
the same reference numerals as used in the first embodiment are used to designate
the corresponding elements of the second through fourth embodiments, and an explanation
of which is dispensed with. Here, the second through fourth embodiments are created
based on the following findings.
[0044] Common two-way speaker devices are constituted by a speaker unit for middle and low
frequency ranges and a speaker unit for a high frequency range (see Patent Document
2, for example). In these speaker devices, sounds in the low frequency range and sounds
in the middle frequency range are emitted from the same speaker unit. Also, even in
the case where different audio amplifiers are provided for different frequency ranges,
the sounds in the low frequency range and the sounds in the middle frequency range
are amplified by the same audio amplifier. Thus, in the case where a sound quality
is adjusted by, e.g., boosting the low frequency range, the middle frequency range
is also boosted slightly due to this adjustment, making it difficult to execute control
in a state in which the frequency ranges are completely separated from each other.
Also, if the middle frequency range is also boosted due to the effects of the low
frequency range, a heavy load is imposed on the audio amplifier, unfortunately.
[0045] Incidentally, the speaker can be provided on the back surface for a design of the
front surface. For example, an elongated housing shaped like a quadrangular prism
and standing upright; and a plurality of speaker units provided on all respective
four side surfaces of the housing (see Patent Document 1, for example). This speaker
device delays and adjusts the timing at which each of the speaker units outputs an
audio signal, to output a sound beam as a sound wave with directivity. This speaker
device outputs the sound beams toward a floor and a ceiling of a room to cause the
sound beams to be reflected a plurality of times, and accordingly indirect sounds
reach a listener from many directions. This configuration achieves an effect in which
the listener does not feel an accurate position of the speaker device.
[0046] In the case where the speaker device disclosed in Patent Document 1 is placed in,
e.g., a corner of a room, and a sound is emitted from a speaker unit facing walls
of the corner, the emitted sound becomes unclear because the sound is muffled in the
middle frequency range in the corner of the room. Also, the plurality of speaker units
are as described above provided on all the respective four side surfaces of the housing
in the speaker device disclosed in Patent Document 1. Thus, the side surfaces cannot
be decorated, thereby limiting a design of the housing.
[0047] Therefore, the second through fourth embodiments are developed to provide a speaker
device with (i) improved controllability of sound quality of a two-way speaker device,
(ii) clarity which is maintained even when a sound is reflected off a wall surface,
and (iii) high flexibility in design of a housing.
[0048] There will be explained a speaker device according to the second embodiment of the
present invention with reference to figures. Figs. 7-9 are views for explaining the
second embodiment of the present invention. Fig. 7 is a block diagram illustrating
the speaker device, Fig. 8 is a view illustrating characteristics of filters, and
Fig. 9 illustrates a stereo configuration using two speaker devices.
[0049] The speaker device 500 includes a full-range speaker unit 510 for emitting sounds
in the low frequency range and the high frequency range, and a midrange speaker unit
511 for emitting sounds in the middle frequency range. The middle frequency range
is principally a frequency range which covers human voices and ranges from 100 Hz
to 7000 Hz, for example. It is noted that the middle frequency range is not limited
to this range. For example, the middle frequency range may be a frequency range for
a telephone network which ranges from 300 Hz to 3400 Hz. The high frequency range
is a frequency range higher than the middle frequency range. The low frequency range
is a frequency range lower than the middle frequency range. Hereinafter, a lower limit
frequency of the middle frequency range will be referred to as "FL", and an upper
limit frequency of the middle frequency range as "FH".
[0050] In the block diagram in Fig. 7, the speaker device 500 includes an audio-signal input
portion 512, a signal processor 501, a speaker driving portion 502, and speaker units
510, 511. The signal processor 501 includes low-pass filters 520, 527, a high-pass
filter 521, gain adjusters 523, 524, 528, and an adder 525. The speaker driving portion
502 includes amplifiers 526, 529.
[0051] The audio-signal input portion 512 inputs an audio signal and supplies it to the
low-pass filters 520, 527 and the high-pass filter 521. The low-pass filter 527 passes
signals with a frequency lower than or equal to an upper limit frequency FH of the
middle frequency range. Fig. 8(A) illustrates a frequency response of the low-pass
filter 527. A gain of an audio signal having passed through the low-pass filter 527
is adjusted by the gain adjuster 528 and amplified by the amplifier 529, and then
the audio signal is supplied to the speaker unit 511. The audio signal output from
the low-pass filter 527 contains components of the low frequency range. Although this
signal is to be supplied to the speaker unit 511, the speaker unit 511 is for the
midrange and cannot emit sounds in the low frequency range as indicated by the broken
line in Fig. 8(A). Thus, the sound emitted from the speaker unit 511 is such a sound
in the middle frequency range that the filter response in Fig. 8(A) is corrected by
the broken line. It is noted that the low-pass filter 527 may be a band-pass filter
for the middle frequency range. The gain adjuster 528 may be included in the low-pass
filter 527.
[0052] The low-pass filter 520 passes signals with a frequency lower than or equal to a
lower limit frequency FL of the middle frequency range. Fig. 8(B) illustrates a frequency
response of the low-pass filter 520. The curve LPF on the left side indicates a response
of the low-pass filter 520. A gain of an audio signal in the low frequency range which
has passed through the low-pass filter 520 is adjusted by the gain adjuster 523, and
then the audio signal is input to the adder 525. The high-pass filter 521 passes signals
with a frequency higher than or equal to the upper limit frequency FH of the middle
frequency range. Fig. 8(B) illustrates frequency response of the high-pass filter.
The curve HPF on the right side indicates a response of the high-pass filter 521.
A gain of an audio signal in the high frequency
range which has passed through the high-pass filter 521 is adjusted by the gain adjuster 524,
and then the audio signal is input to the adder 525. The adder 525 synthesizes the
audio signal in the low frequency range and the audio signal in the high frequency
range by adding them together. This synthesized audio signal is amplified by the amplifier
526 and supplied to the speaker unit 510. It is noted that the gain adjusters 523,
524 may be included respectively in the low-pass filter 520 and the high-pass filter
521.
[0053] As described above, the signal in the component of the low frequency range and the
signal in the component of the high frequency range are amplified by the same amplifier,
and sounds based on these signals are emitted from the same speaker unit 510, and
the signal in the component of the middle frequency range is amplified by the amplifier
different from that used for amplifying the signal in the component of the low frequency
range, and a sound based on the signal in the component of the middle frequency range
is emitted from the speaker unit different from that used for emitting a sound based
on the signal in the component of the low frequency range. This configuration enables
the two-way speaker device to separate the high frequency range, the middle frequency
range, and the low frequency range from each other, facilitating independent gain
adjustment. Also, in conventional speaker devices with frequency bands separated into
a band for high sounds and a band for middle and low sounds, in the case where the
low frequency range is boosted, for example, a gain of the middle frequency range
is increased due to the boost of the low frequency range, a sound quality of the middle
frequency range is changed, and a burden is placed on an amplifier for amplifying
the middle and low sounds. In the speaker device 500 illustrated in Figs. 7-9, however,
even when the low frequency range is boosted, the middle frequency range is not affected,
so that the sound quality is not changed, and no burden is placed on the speaker unit.
[0054] It is noted that the speaker unit 510 is provided on a back surface of the device
in this embodiment.
[0055] Fig. 9 is a view illustrating a stereo configuration using two speaker devices 500
each illustrated in Fig. 7. This stereo speaker system includes a speaker device 500L
for the left channel and a speaker device 500R for the right channel. Fig. 10 is a
view illustrating an integral-type stereo speaker device 505 according to a third
embodiment of the present invention. This speaker device 505 is configured using a
range separation method of the two-way speaker illustrated in Figs. 7-9.
[0056] The speaker device 505 in Fig. 10 includes: a speaker unit 511C for the middle frequency
range which is provided on a front surface of the speaker device 505; and full-range
speaker units 510L, 510R (for the left and right channels) provided on a back surface
of the speaker device 505. In Fig. 10, the speaker unit 511C, for the middle frequency
range, provided on the front surface is oriented frontward but may be oriented in
another direction. For example, the speaker device may be configured such that the
speaker unit is oriented upward, and a reflector may be provided for reflecting emitted
sound wave in the front direction.
[0057] Fig. 11 is a block diagram illustrating the speaker device 505 illustrated in Fig.
10. As illustrated in this block diagram, the signal processor 501 includes low-pass
filters 520L, 520R, 527L, 527R, high-pass filters 521L, 521R, gain adjusters 523L,
523R, 524L, 524R, 528L, 528R, and adders 525L, 525R, 530C. The speaker driving portion
502 includes amplifiers 526L, 526R, 529C.
[0058] A left-channel audio-signal input portion 512L inputs an audio signal in the left
channel and supplies it to the low-pass filters 520L, 527L and the high-pass filter
521L. The low-pass filter 520L passes signals with a frequency lower than or equal
to the lower limit frequency FL of the middle frequency range. A gain of an audio
signal in the low frequency range which has passed through the low-pass filter 520L
is adjusted by the gain adjuster 523L, and then the audio signal is input to the adder
525L. The high-pass filter 521L passes signals with a frequency higher than or equal
to the upper limit frequency FH of the middle frequency range. A gain of an audio
signal in the high frequency range which has passed through the high-pass filter 521L
is adjusted by the gain adjuster 524L, and then the audio signal is input to the adder
525L. The adder 525L synthesizes the audio signal in the low frequency range and the
audio signal in the high frequency range in the left channel by adding them together.
This synthesized audio signal is amplified by the amplifier 526L and supplied to the
speaker unit 510L. It is noted that the gain adjusters 523L, 524L may be included
respectively in the low-pass filter 520L and the high-pass filter 521L.
[0059] A right-channel audio-signal input portion 512R inputs an audio signal in the right
channel and supplies it to the low-pass filters 520R, 527R and the high-pass filter
521R.
[0060] The low-pass filter 520R passes signals with a frequency lower than or equal to the
lower limit frequency FL of the middle frequency range. A gain of an audio signal
in the low frequency range which has passed through the low-pass filter 520R is adjusted
by the gain adjuster 523R, and then the audio signal is input to the adder 525R. The
high-pass filter 521R passes signals with a frequency higher than or equal to the
upper limit frequency FH of the middle frequency range. A gain of an audio signal
in the high frequency range which has passed through the high-pass filter 521R is
adjusted by the gain adjuster 524R, and then the audio signal is input to the adder
525R. The adder 525R synthesizes the audio signal in the low frequency range and the
audio signal in the high frequency range in the right channel by adding them together.
This synthesized audio signal is amplified by the amplifier 526R and supplied to the
speaker unit 510R. It is noted that the gain adjusters 523R, 524R may be included
respectively in the low-pass filter 520R and the high-pass filter 521R.
[0061] The low-pass filter 527L for the left channel passes signals with a frequency lower
than or equal to the upper limit frequency FH of the middle frequency range. A gain
of an audio signal having passed through the low-pass filter 527L is adjusted by the
gain adjuster 528L, and then the audio signal is input to the adder 530C. The low-pass
filter 527R for the right channel passes signals with a frequency lower than or equal
to the upper limit frequency FH of the middle frequency range. A gain of an audio
signal having passed through the low-pass filter 527R is adjusted by the gain adjuster
528R, and then the audio signal is input to the adder 530C. The adder 530C synthesizes
the audio signals in the middle frequency range in the left and right channels by
adding them together. This synthesized audio signal is amplified by the amplifier
529C and supplied to the speaker unit 511C. It is noted that the gain adjusters 528L,
528R may be included respectively in the low-pass filter 527L and the low-pass filter
527R.
[0062] The audio signal output from the low-pass filters 527L, 527R contains components
of the low frequency range, but the speaker unit 511C for the midrange speaker unit
cannot emit sounds in the low frequency range. Thus, the sound emitted from the speaker
unit 511C is such a sound in the middle frequency range that the filter response in
Fig. 8(A) is corrected by the broken line. It is noted that the low-pass filters 527L,
527R may be a band-pass filter for the middle frequency range.
[0063] This integral stereo speaker illustrated in Figs. 10 and 11 is configured such that
the single speaker unit 511C provided on the front surface emits the sound obtained
by synthesizing the sounds in the middle frequency range in the left and right channels,
and the two speaker units 510L, 510R provided on the back surface emit the sounds
in the low frequency range and the high frequency range, separately in the respective
left and right channels. Thus, this speaker device achieves the following effects
in addition to those achieved by the speaker device illustrated in Figs. 7-9.
[0064] Only one small speaker unit is provided on the front surface, or no speaker is provided
on the front surface in the case where the speaker unit is oriented upward, resulting
in improvement in design of the front surface.
[0065] A large speaker unit can be provided on the back surface, making it possible to emit
low sounds of high quality without deterioration of design of the front surface.
[0066] The sounds in the high frequency range are emitted from the two speaker units provided
on the back surface, resulting in generation of a right and left stereo feeling using
reflection against walls.
[0067] The speaker unit provided on the front surface emits the sounds in the middle frequency
range such as human voices, resulting in clear audibility without muffled sounds.
[0068] It is noted that the one speaker unit 511C for the middle frequency range is provided
on the front surface in the embodiment illustrated in Figs. 10 and 11. In the case
where a stereo feeling in the middle frequency range is to be emphasized, for example,
middle-frequency-range speaker units for the respective left and right channels may
be provided on the front surface.
[0069] There will be next explained a speaker device according to a fourth embodiment of
the present invention with reference to drawings. This speaker device 301 is shaped
such that the speaker device 505 illustrated in Figs. 10 and 11 is modified so as
to be elongated vertically, and the speaker unit 511C provided on the front surface
is modified so as to be provided on the upper side of a housing and oriented upward.
Figs. 12(A)-12(C) are external views of the speaker device 301. Fig. 12(A) is a front
elevational view of the speaker device 301, Fig. 12(B) is a right side view thereof,
and Fig. 12(C) is a rear view thereof.
[0070] The speaker device 301 includes: a housing 311 for accommodating a plurality of speakers;
a base 314 shaped like a round board and provided on a floor surface to support the
housing 311; and a pillow 313 shaped like a rod and connecting the housing 311 and
the base 314 to each other. The housing 311 is supported by the pillow 313 and the
base 314 and provided upright in the vertical direction.
[0071] The housing 311 is shaped like a substantially quadrangular prism which slightly
tapers in width toward an upper end thereof. That is, the housing 311 has a quadrangular-pyramidal
trapezoid shape (a shape obtained by horizontally cutting out a vertex portion or
a head portion from a quadrangular pyramid in a plane parallel with a bottom surface
of the pyramid), accurately. The angle of inclination of a side surface of the housing
311 with respect to the vertical line is 2%. The speaker device 301 is installed in
a state in which an edge line portion 319 interposed between two side surfaces of
the speaker device 301 is located on a front side (a user side). In the following
explanation, the front direction of the speaker device is referred to as a front direction,
and the back direction is referred to as a rear direction. Also, a right and left
direction is defined based on a state in which the speaker device 301 is viewed from
a user located on a front side.
[0072] In this speaker device 301, as illustrated in Figs. 12(B) and 12(C), the speaker
units 510L, 510R are provided so as to be oriented in the rear direction. A speaker
grille 312 is provided on a back portion of the housing 311. As a result, the speaker
grille 312 need not be provided on a front portion of the speaker device 301.
[0073] The interior of the housing 311 is divided by two partition plates into three spaces
in the up and down direction. The three spaces include: an upper space as a middle-frequency-range
speaker box 330 for accommodating the speaker unit 511C; a central space as a stereo
speaker box 331 for accommodating the speaker units 510L, 510R; and a lower space
as a circuit box 332 for accommodating an electronic circuit 315.
[0074] An upper surface of the middle-frequency-range speaker box 330 has an opening in
which the speaker unit 511C is mounted so as to be oriented upward. A head piece 310
is provided on the upper side of the speaker unit 511C such that sounds emitted from
the speaker unit 511C are reflected off the head piece 310 in the front direction.
[0075] It is noted that the head piece 310 in the fourth embodiment has the same construction
as that of the head piece 10 illustrated in Fig. 4.
[0076] Fig. 13 is a view illustrating an example of an installation position of the speaker
device 301. The speaker device 301 is installed at, e.g., a corner of a room in a
state in which a back portion of the speaker device 301 faces a wall. Since no speaker
units or no speaker grille is provided on the front portion of the speaker device
301, the speaker device 301 functions also as a decorative interior unlike common
speaker devices.
[0077] When a sound signal is input to the speaker device 301, sounds are emitted from the
speaker units 510L, 510R for the respective left and right channels. Since the speaker
units 510L, 510R are oriented in the back direction (i.e., so as to face the wall),
the sounds emitted from the speaker units 510L, 510R for the respective left and right
channels are reflected off a wall surface and propagate in the front direction (i.e.,
toward a central portion of the room). Sounds in the high frequency range among the
sounds emitted from the speaker units 510L, 510R travel straight when compared to
sounds in the other frequency ranges, and accordingly the sounds emitted from the
speaker units 510L, 510R are well reflected off the wall, whereby a listener feels
a stereo feeling. Since sounds in the low frequency range are emitted with a small
amount of spatial impression in audibility, even when the listener listens to the
sounds as if the sounds are made near the wall surface, the user (the listener) feels
little discomfort. In contrast, the middle frequency range contains human speaking
voices and human singing voices, and when sounds in the middle frequency range are
reflected off the wall surface, the sounds are attenuated greatly and thereby muffled,
resulting in lowered clarity. To solve this problem, the speaker device 301 extracts
components of the middle frequency range from sounds in the left and right channels
and emits sounds in the middle frequency range from the speaker unit 511C oriented
upward. Although the speaker unit 511C is oriented upward, the emitted sounds in the
middle frequency range are well propagated frontward by the head piece 310 provided
on the upper side of the speaker unit 511C. As a result, the user can clearly listen
to the sounds in the low through high frequency ranges without discomfort.
[0078] The electronic circuit 315 is disposed in the circuit box 332 of the housing 311.
Fig. 14 is a block diagram illustrating a main portion of the electronic circuit 315.
The electronic circuit 315 includes a controller 350, the signal processor 501, an
audio amplifier 502, an input selector 353, a Bluetooth (registered trademark) communication
circuit 354, and a cable connector 355.
[0079] The controller 350 is constituted by a microcomputer. A light receiving circuit 340
is connected to the controller 350, and this light receiving circuit 340 receives
an infrared signal transmitted from an infrared remote control, not shown. The light
receiving circuit 340 converts the received infrared signal to an electronic signal
and inputs it to the controller 350. Based on the signals received from the light
receiving circuit 340, the controller 350 selects an input signal in the input selector
353, adjusts sound quality in the signal processor 351, adjusts a sound volume in
the audio amplifier 352, turns on and off the Bluetooth communication circuit 354,
and sets a password, for example.
[0080] The signal processor 501 is similar in configuration to the signal processor illustrated
in Fig. 11. That is, the signal processor 501 adjusts sound quality of an audio signal
(a two-channel stereo signal) input from the input selector 353. Also, the signal
processor 501 extracts components in the middle frequency range, from signals in the
right and left channels, and synthesizes the extracted components to output the obtained
signal as an audio signal in a third channel (i.e., a center channel). The speaker
driving portion 502 is similar in configuration to the speaker driving portion illustrated
in Fig. 11. That is, the speaker driving portion 502 includes amplifiers 526L, 526R
and an amplifier 529 for three channels which respectively amplify audio signals in
the left channel, the right channel, and the middle frequency range. The speaker driving
portion 502 outputs each of the amplified signals to a corresponding one of the speaker
units 510L, 510R and the speaker unit 511C.
[0081] As illustrated in Fig. 13, in the case where the speaker device 301 is placed in
a state in which its back surface faces the wall of the room, the sounds emitted from
the speaker units 510L, 510R are reflected off the wall surface (principally in the
high frequency range). As a result, even the sounds emitted from the slim housing
echo with spatial impression. In this case, if the sounds contain sounds in the middle
frequency range, the sounds become unclear due to the reflection against the wall
surface. In the present application, however, the sounds in the middle frequency range
are emitted frontward from the speaker unit 511C. Thus, sounds in the left and right
channels echo clearly in all the frequency ranges with spatial impression. Also, no
speaker unit or no speaker grille is provided on the front surface of the housing
311, resulting in increase in flexibility in design for the front surface. Also, sounds
in adjacent frequency ranges are not emitted from one speaker unit, enabling gain
adjustment for the high frequency range, the middle frequency range, and the low frequency
range independently of each other.
[0082] It is noted that the shape of the housing 311 of the speaker device 301 is not limited
to the quadrangular-pyramidal trapezoid shape and may be a column shape such as a
conical trapezoid shape, a circular cylindrical shape, and a prism shape. The speaker
unit 511C emits the sounds upward in the fourth embodiment, but the present invention
is not limited to this construction. For example, the speaker unit 511C may be configured
to emit the sounds frontward as in the second and third embodiments. That is, the
speaker device 301 includes: a first filter configured to take at least a signal in
a component of the middle frequency range containing a human voice, out of an audible
frequency range of the sound signal; a second filter configured to take, out of the
audible frequency range of the sound signal, a signal in a component of the low frequency
range and a signal in a component of the high frequency range, other than the signal
in the component of the middle frequency range; a second speaker unit configured to
emit the signal output from the first filter; and a first speaker unit configured
to emit the signal output from the second filter.
EXPLANATION OF REFERENCE NUMERALS
[0083] 1: Speaker Device, 10: Head Piece, 11: Housing, 15: Electronic Circuit, 20, 21, 22:
Speaker Unit, 30: Middle-frequency-range Speaker Box, 31: Stereo Speaker Box, 32:
Circuit Box, 105: Reflector, 301, 500, 505: Speaker Device, 310: Head Piece, 311:
Housing, 315: Electronic Circuit, 320, 321, 322: Speaker Unit, 330: Middle-frequency-range
Speaker Box, 331: Stereo Speaker Box, 332: Circuit Box, 501: Signal Processor, 502:
Speaker Driving Portion
1. A speaker device (1; 500; 505; 301), comprising:
a housing (11; 311) comprising a back surface formed with an opening, and an upper
surface formed with an opening; with a front side configured to be a user side,
at least one first speaker unit (21, 22; 510, 510R, 510L) disposed in the opening
of the back surface;
at least one second speaker unit (20; 511; 511C) disposed in the opening of the upper
surface; and
an electronic circuit (15; 315) configured to supply a sound signal to the at least
one first speaker unit (21, 22; 510, 510R, 510L) and supply, to the at least one second
speaker unit (20; 511; 511C), a partial frequency range of the sound signal,
the electronic circuit (15, 315) further comprising:
a first filter (527; 527R, 527L) configured to select at least a signal in frequencies
of a middle frequency range covering human voices, out of an audible frequency range
of the sound signal; and
a second filter (520, 521; 520R, 520L, 521R, 521L) configured to select a signal in
frequencies of each of a low frequency range and a high frequency range, out of the
audible frequency range of the sound signal, wherein the signal in the frequencies
of each of the low frequency range and the high frequency range is different from
the signal in the frequencies of the middle frequency range,
wherein the signal output from the first filter (527; 527R, 527L) is output to the
at least one second speaker unit (511; 511C), and
wherein the signal output from the second filter (520, 521; 520R, 520L, 521R, 521L)
is output to the at least one first speaker unit (510; 510R, 510L).
2. The speaker device (1; 500; 505; 301) according to claim 1, further comprising a reflector
(105) disposed on an upper side of the at least one second speaker unit (20; 511;
511C) and configured to reflect a sound emitted from the at least one second speaker
unit (20; 511; 511C), toward the front side of the housing (11; 311).
3. The speaker device (1; 500; 505; 301) according to any one of claims 1 through 2,
wherein the housing (11; 311) is divided into a plurality of layers at least comprising:
an upper layer box comprising the opening of the upper surface and accommodating the
at least one second speaker unit (20; 511; 511C); a middle layer box comprising the
opening of the back surface and accommodating the at least one first speaker unit
(21, 22; 510; 510R, 510L); and a lower layer box accommodating the electronic circuit
(15; 315).
4. The speaker device (1; 500; 505; 301) according to any one of claims 1 through 3,
wherein the at least one first speaker unit (21, 22; 510; 510R, 510L) comprises a
plurality of speaker units (21, 22; 510; 510R, 510L) to each of which a sound signal
of corresponding at least one of a plurality of channels is to be supplied, and
wherein the electronic circuit (15; 315) is configured to supply, to the at least
one second speaker unit (20; 511; 511C), a signal obtained by extracting the signal
in frequencies of a middle frequency range covering human voices from the sound signal
in each of the plurality of channels and mixing the extracted signals.
5. The speaker device (500; 505; 301) according to one of the preceding claims,
wherein the at least one second speaker unit (511; 511C) is a middle-frequency-range
speaker (511; 511C) with a reduced sound emission characteristic of the low frequency
range, and
wherein the first filter (527; 527R, 527L) is a low-pass filter (527; 527R, 527L)
configured to select a signal in frequencies of a frequency range which is less than
or equal to the middle frequency range, and the frequencies of the frequency range
which is less than or equal to the middle frequency range contains frequencies of
the low frequency range.
6. The speaker device (500; 505; 301) according to one of the preceding claims,
wherein the sound signal is a stereo signal in right and left channels,
wherein each of right and left first speaker units (510R, 510L) as the at least one
first speaker unit (510, 510R, 510L) is configured such that a signal in a corresponding
one of the left and right channels is input to said each of right and left first speaker
units (510R, 510L), and
wherein a signal obtained by applying the first filter and mixing the right and left
channels is input to one second speaker unit (511; 511C) as the at least one second
speaker unit (511; 511C).
1. Lautsprechervorrichtung (1; 500; 505; 301), die Folgendes umfasst:
ein Gehäuse (11; 311), das eine Rückseitenoberfläche umfasst, die mit einer Öffnung
ausgebildet ist, und eine obere Oberfläche, die mit einer Öffnung ausgebildet ist;
mit einer Frontseite, die konfiguriert ist, um eine Benutzerseite zu sein,
mindestens eine erste Lautsprechereinheit (21, 22; 510, 510R, 510L), die in der Öffnung
der Rückseitenoberfläche angeordnet ist;
mindestens eine zweite Lautsprechereinheit (20; 511; 511C), die in der Öffnung der
oberen Oberfläche angeordnet ist; und
eine elektronische Schaltung (15; 315), die konfiguriert ist, um ein Tonsignal zu
der mindestens einen Lautsprechereinheit (21, 22; 510, 510R, 510L) zu liefern und
zu der mindestens einen zweiten Lautsprechereinheit (20; 511; 511C) einen teilweisen
Frequenzbereich des Tonsignals zu liefern,
wobei die elektronische Schaltung (15, 315) weiter Folgendes umfasst:
ein erstes Filter (527; 527R, 527L), das konfiguriert ist, um mindestens ein Signal
in Frequenzen eines Mittelfrequenzbereichs, der menschliche Stimmen abdeckt, aus einem
hörbaren Frequenzbereich des Tonsignals auszuwählen; und
ein zweites Filter (520, 521; 520R, 520L, 521R, 521L), das konfiguriert ist, um ein
Signal in Frequenzen jedes eines Niederfrequenzbereichs und eines Hochfrequenzbereichs
aus dem hörbaren Frequenzbereich des Tonsignals auszuwählen, wobei das Signal in den
Frequenzen jedes des Niederfrequenzbereichs und des Hochfrequenzbereichs von dem Signal
in den Frequenzen des Mittelfrequenzbereichs verschieden ist,
wobei das Signal, das aus dem ersten Filter (527; 527R, 527L) ausgegeben wird, zu
der mindestens einen zweiten Lautsprechereinheit (511; 511C) ausgegeben wird, und
wobei das Signal, das aus dem zweiten Filter (520, 521; 520R, 520L, 521R, 521L) ausgegeben
wird, zu der mindestens einen ersten Lautsprechereinheit (510; 510R, 510L) ausgegeben
wird.
2. Lautsprechervorrichtung (1; 500; 505; 301) nach Anspruch 1, die weiter einen Reflektor
(105) umfasst, der auf einer oberen Seite der mindestens einen zweiten Lautsprechereinheit
(20; 511; 511C) angeordnet und konfiguriert ist, um einen Ton, der von der mindestens
einen zweiten Lautsprechereinheit (20; 511; 511C) abgegeben wird, zu der Frontseite
des Gehäuses (11; 311) zurückzuwerfen.
3. Lautsprechervorrichtung (1; 500; 505; 301) nach einem der Ansprüche 1 bis 2, wobei
das Gehäuse (11; 311) in eine Vielzahl von Schichten geteilt ist, die mindestens Folgendes
umfassen: eine Box der oberen Schicht, die die Öffnung der oberen Oberfläche umfasst
und die mindestens eine zweite Lautsprechereinheit (20; 511; 511C) unterbringt; eine
Box der mittleren Schicht, die die Öffnung der Rückseitenoberfläche umfasst und die
mindestens eine erste Lautsprechereinheit (21, 22; 510; 510R, 510L) unterbringt; und
eine Box der unteren Schicht, die die elektronische Schaltung (15; 315) unterbringt.
4. Lautsprechervorrichtung (1; 500; 505; 301) nach einem der Ansprüche 1 bis 3,
wobei die mindestens eine erste Lautsprechereinheit (21, 22; 510; 510R, 510L) eine
Vielzahl von Lautsprechereinheiten (21, 22; 510; 510R, 510L) umfasst, zu welchen jeweils
ein Tonsignal eines entsprechenden mindestens einen einer Vielzahl von Kanälen zu
liefern ist, und
wobei die elektronische Schaltung (15; 315) konfiguriert ist, um zu der mindestens
einen zweiten Lautsprechereinheit (20; 511; 511C) ein Signal zu liefern, das durch
Extrahieren des Signals in Frequenzen eines Mittelfrequenzbereichs, der menschliche
Stimmen abdeckt, aus dem Tonsignal in jedem der Vielzahl von Kanälen und Mischen der
extrahierten Signale erhalten wird.
5. Lautsprechervorrichtung (500; 505; 301) nach einem der vorstehenden Ansprüche,
wobei die mindestens eine zweite Lautsprechereinheit (511; 511C) ein Mittelfrequenzbereichslautsprecher
(511; 511C) mit einem reduzierten Tonabgabemerkmal des Niederfrequenzbereichs ist,
und
wobei das erste Filter (527; 527R, 527L) ein Tiefpassfilter (527; 527R, 527L) ist,
das konfiguriert ist, um ein Signal in Frequenzen eines Frequenzbereichs, der kleiner
als der oder gleich dem Mittelfrequenzbereich ist, auszuwählen, und die Frequenzen
des Frequenzbereichs, der kleiner als der oder gleich dem Mittelfrequenzbereich ist,
Frequenzen des Niederfrequenzbereichs enthält.
6. Lautsprechervorrichtung (500; 505; 301) nach einem der vorstehenden Ansprüche,
wobei das Tonsignal ein Stereosignal in rechten und linken Kanälen ist,
wobei jede der rechten und linken ersten Lautsprechereinheiten (510R, 510L) als die
mindestens eine erste Lautsprechereinheit (510, 510R, 510L) derart konfiguriert ist,
dass ein Signal in einem entsprechenden eines der linken und rechten Kanäle zu jeder
der rechten und linken ersten Lautsprechereinheiten (510R, 510L) eingegeben wird,
und
wobei ein Signal, das durch Anwenden des ersten Filters und Mischen der rechten und
linken Kanäle erhalten wird, zu einer zweiten Lautsprechereinheit (511; 511C) als
die mindestens eine zweite Lautsprechereinheit (511; 511C) eingegeben wird.