U.S. patent application number 12/703854 was filed with the patent office on 2010-06-10 for vehicle-mounted three dimensional sound field reproducing unit.
Invention is credited to Daisuke ARAI, Fujio Hayakawa, Masahiro Ieda, Toyoaki Kitano, Yutaka Kotani, Yutaka Yamagishi.
Application Number | 20100142734 12/703854 |
Document ID | / |
Family ID | 29252577 |
Filed Date | 2010-06-10 |
United States Patent
Application |
20100142734 |
Kind Code |
A1 |
ARAI; Daisuke ; et
al. |
June 10, 2010 |
VEHICLE-MOUNTED THREE DIMENSIONAL SOUND FIELD REPRODUCING UNIT
Abstract
In correspondence with the left and right external ears of a
listener occupying a seat, a three dimensional sound field
reproducing unit includes at least more than two speakers disposed
on a headrest on the top of a backrest of the seat, and three
dimensional signal processing means which converts an output signal
from a sound source into a three dimensional sound field signal for
supplying it to each of the speakers. Three dimensional sound field
with high accuracy and fidelity is reproduced near the external
ears of the listener.
Inventors: |
ARAI; Daisuke; (Tokyo,
JP) ; Hayakawa; Fujio; (Tokyo, JP) ; Kitano;
Toyoaki; (Tokyo, JP) ; Kotani; Yutaka; (Tokyo,
JP) ; Yamagishi; Yutaka; (Tokyo, JP) ; Ieda;
Masahiro; (Tokyo, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
29252577 |
Appl. No.: |
12/703854 |
Filed: |
February 11, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10312883 |
Jan 2, 2003 |
7684577 |
|
|
PCT/JP01/04462 |
May 28, 2001 |
|
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12703854 |
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Current U.S.
Class: |
381/302 |
Current CPC
Class: |
H04R 5/02 20130101; H04R
2499/13 20130101; B60N 2/885 20180201; B60R 2011/0084 20130101;
B60R 2011/0015 20130101; H04S 3/00 20130101; B60R 11/0217 20130101;
H04R 5/023 20130101; B60N 2/879 20180201; B60R 2011/0017 20130101;
B60R 2011/0085 20130101; A47C 7/72 20130101; H04R 5/027 20130101;
H04S 1/002 20130101 |
Class at
Publication: |
381/302 |
International
Class: |
H04R 5/02 20060101
H04R005/02 |
Claims
1. A three dimensional sound field reproducing unit including at
least two speakers for generating sound fields near external ears
in correspondence with left and right external ears of a listener
occupying a seat; and a three dimensional signal processing means
for converting an output signal from a sound source into a three
dimensional sound field signal; said unit comprising: a seated
position memory which stores therein an seated position of the
listener; a seated position control part for reading out the seated
position from said seated position memory interlocked with an
adjustment of the seated position; and a convolution coefficient
control part for reading out a convolution coefficient based on the
seated position supplied from said seated position control part for
supplying it to said three dimensional signal processing means.
2. A three dimensional sound field reproducing unit including at
least two speakers for generating sound fields near external ears
in correspondence with left and right external ears of a listener
occupying a seat; and three dimensional signal processing means for
converting an output signal from a sound source into a three
dimensional sound field signal for supplying it to each of said
speakers; said unit comprising: a convolution coefficient memory
which stores therein, as an previously measured inverse transfer
coefficient, an inverse transfer function; a transfer
characteristic measuring part for reading out a convolution
coefficient from said convolution coefficient memory depending on
the measured transfer characteristic; and a convolution coefficient
control part for supplying the convolution coefficient supplied
from said transfer characteristic measuring part to said three
dimensional signal processing part.
Description
[0001] This Application is a divisional application of Ser. No.
10/312,883 filed on Jan. 2, 2003 which is a national phase
application under 35U.S.C. .sctn.371 of PCT International
Application PCT/JP01/04462 which has an International filing date
of May 28, 2001, which designated the United States of America.
TECHNICAL FIELD
[0002] This invention relates to a vehicle-mounted three
dimensional sound field reproducing unit capable of making a
listener enjoyed perceiving a three dimensional sound field with
rich presence by disposing speakers in a position close to a head
of the listener inside a vehicle compartment and by controlling the
sound fields near external ears of the listener.
BACKGROUND ART
[0003] Conventionally, many systems have been proposed in which a
listener enjoys listening to a stereophonic sound field by wearing
a headphone. These systems are mainly based on the principle that
the sound arrived at eardrums is controlled to reproduce the
original sound field. However, since the distance from the external
ears to the eardrums are largely different every individual, the
sound field to be localized in the front may sometimes shift to the
rear, which dulls the sense of distance.
[0004] In addition, there have been devised techniques in which, by
utilizing speakers in a room or inside a vehicle compartment, the
arriving time of the sound waves from the speakers to a listener is
made even to control the position of the image, or in which a
transfer characteristic is convoluted into the input signal to be
inputted to the speakers to control the sound field. However, these
techniques have shortcomings that they are valid only within a
small listening area and are for instance effective only for one
listener who sits on a target seat inside the vehicle compartment
(hereinafter also referred to as the seat). Still further, these
techniques exert a different effect that largely varies depending
on a situation where other listeners are seated inside the vehicle
and a situation where nobody is.
[0005] This invention has been made to solve the above-described
and other problems, and has an object of providing a
vehicle-mounted three dimensional sound field reproducing unit
which enables reproduction of a) a sound field with high accuracy
and fidelity near the external ears of the listener without wearing
a headphone, and b) a sound field with high accuracy and fidelity
as compared with the conventional headphone having one speaker per
one ear, as a result of adoption of at least two or more speakers
(i.e., four or more speakers for both the ears).
DISCLOSURE OF INVENTION
[0006] A vehicle-mounted three dimensional sound field reproducing
unit according to this invention includes at least two speakers
provided near a headrest which is on the top of a backrest of a
seat in correspondence with left and right external ears of a
listener occupying the seat so as to reproduce sound fields near
the external ears; and three dimensional signal processing means
for converting an output signal from a sound source into a three
dimensional sound field signal for supplying it to each of the
speakers.
[0007] According to this invention, it is possible to position the
head of the listener between the left and right speakers, and the
distance to the sound fields near the external ears as the target
for control can be made small. As a result, this makes the listener
enjoyed listening to the three dimensional sound field and reduces
crosstalk between the left and right speakers.
[0008] In the vehicle-mounted three dimensional sound field
reproducing unit according to this invention a pair of left and
right recessed portions are formed in a front of the headrest so as
to dispose the speakers sequestered from a surface of each of the
recessed portions.
[0009] According to this invention, it surely reduces crosstalk
between the left and right speakers.
[0010] In the vehicle-mounted three dimensional sound field
reproducing unit according to this invention a pair of left and
right recessed portions are provided in a front of the headrest, a
box is provided inside each of the recessed portions so as to
sandwich a head of the listener, and the speakers are provided in
the box in correspondence with the left and right external ears of
the listener.
[0011] According to this invention, it is possible to dispose the
speakers in a position close to the external ears of the listener,
which yields a state akin to that where an ideal headphone is worn
by the listener.
[0012] The vehicle-mounted three dimensional sound field
reproducing unit according to this invention includes at least two
speakers provided on a ceiling so as to surround a head of a
listener occupying a seat in correspondence with left and right
external ears of the listener; and three dimensional signal
processing means for converting an output signal from a sound
source into a three dimensional sound field signal for supplying it
to each of the speakers.
[0013] According to this invention, the distance between the
speakers and the head of the listener becomes short, so that it is
possible to reproduce a three dimensional sound field with high
accuracy and fidelity near the external ears of the listener and to
give a freedom in the disposition of the speakers.
[0014] The vehicle-mounted three dimensional sound field
reproducing unit according to this invention further includes a
partition plate, provided between the at least two speakers
respectively provided in correspondence with the left and right
external ears, for preventing crosstalk.
[0015] According to this arrangement, it ensures reduction in
crosstalk.
[0016] In the vehicle-mounted three dimensional sound field
reproducing unit according to this invention the at least two
speakers respectively provided in correspondence with the left and
right external ears are disposed close to a partition plate, and a
direction of radiated sounds is respectively directed to the
external ears.
[0017] According to this arrangement, in ensures reduction in
crosstalk.
[0018] In the vehicle-mounted three dimensional sound field
reproducing unit according to this invention the at least two
speakers respectively provided in correspondence with the left and
right external ears and a partition plate provided between the
speakers are integrally assembled into a board, and the board is
provided so as to be movable back and forth and left and right
relative to a ceiling.
[0019] According to this invention, even if the head of the
listener occupying the seat is moved by the back and forth movement
of the seat, it gives a guarantee disposition of the speakers and
the partition plate to most appropriate positions.
[0020] The vehicle-mounted three dimensional sound field
reproducing unit according to this invention includes at least two
speakers respectively provided in a box provided on each end of a
first pole which is slidable left and right so as to sandwich a
head of a listener occupying a seat; a second pole which has
mounted on one end thereof the first pole and is slidable back and
forth; and a vertically slidable third pole which is tiltably
supported on a supporting part, and a tip of which is coupled to an
opposite end of the second pole.
[0021] According to this invention, even if the back and forth
movement of the seat occurs, it appropriately maintains the
positional relationship between the speaker-mounting parts and the
head of the listener.
[0022] The three dimensional sound field reproducing unit according
to this invention further includes a partition plate, retractably
provided on the first pole between the left and right speakers, for
reducing crosstalk.
[0023] According to this invention, by withdrawing the partition
plate backward when not in use, the partition plate does not
interfere, thereby reducing crosstalk.
[0024] In the vehicle-mounted three dimensional sound field
reproducing unit according to this invention the supporting part is
fixed to a roof on a rear seat.
[0025] According to this invention, it enables a fine adjustment of
the positional relationship between the speaker-mounting parts and
the head.
[0026] The vehicle-mounted three dimensional sound field
reproducing unit includes at least two speakers respectively
provided in a center pillar and in a side of an adjacent seat
inside a vehicle compartment so as to sandwich a head of a listener
occupying the seat.
[0027] According to this invention, since a large space is secured
for mounting the speakers, the region of reproduction can be
widened so as to reproduce bass.
[0028] In the vehicle-mounted three dimensional sound field
reproducing unit according to this invention the three dimensional
signal processing means includes left and right crosstalk
cancellers; and a head transfer function part and an inverse
transfer characteristic part respectively provided on an input side
of each of the left and right crosstalk cancellers.
[0029] According to this invention, it allows efficient and sure
reduction in crosstalk.
[0030] In the vehicle-mounted three dimensional sound field
reproducing unit according to this invention the three dimensional
signal processing means includes a time delay part provided on each
of the input sides of the left and right crosstalk cancellers.
[0031] According to this invention, even if the head transfer
function and the crosstalk canceling component vary due to the
positional deviation of the head of the listener and the speakers,
time delay can be corrected.
[0032] The vehicle-mounted three dimensional sound field
reproducing unit according to this invention includes a seated
position memory which stores therein a seated position of the
listener; a seated position control part for reading out the seated
position from the seated position memory interlocked with an
adjustment of the seated position; and a convolution coefficient
control part for reading out a convolution coefficient based on the
seated position supplied from the seated position control part for
supplying it to the three dimensional signal processing means.
[0033] According to this invention, it appropriately cancels
crosstalk irrespective of the change in the seated position.
[0034] The vehicle-mounted three dimensional sound field
reproducing unit according to this invention includes a convolution
coefficient memory which stores therein, as an inverse transfer
coefficient, an inverse transfer function measured in advance; a
transfer characteristic measuring part for reading out a
convolution coefficient from the convolution coefficient memory
depending on the measured transfer characteristic; and a
convolution coefficient control part for supplying the convolution
coefficient supplied from the transfer characteristic measuring
part to the three dimensional signal processing part.
[0035] According to this invention, it appropriately cancels
crosstalk irrespective of the change in the seated position.
BRIEF DESCRIPTION OF DRAWINGS
[0036] FIG. 1 is a schematic diagram showing the state of
arrangement of speakers to reproduce the three dimensional sound
field;
[0037] FIG. 2 is a block diagram of a reproducing circuit for
supplying a reproducing signal to the speakers with an output
signal from a sound source as a three dimensional sound field
signal;
[0038] FIG. 3 is a schematic diagram showing the state in which the
speakers are disposed in a headrest of a front passenger's
seat;
[0039] FIG. 4 is an enlarged side view of the headrest;
[0040] FIG. 5 is a block diagram of a circuit for supplying a
reproducing signal to the speakers;
[0041] FIG. 6 is a distribution diagram of sounds radiated from the
speakers;
[0042] FIGS. 7(a) and 7(b) are diagrams showing the arrangement of
another speakers relative to the headrest, wherein FIG. 7(a) is a
side view and FIG. 7(b) is a perspective view;
[0043] FIG. 8 is a distribution diagram of sounds radiated from the
speakers;
[0044] FIGS. 9(a) through 9(d) are diagrams showing the layout of
another speakers, wherein FIG. 9(a) is a schematic drawing not in
use, FIG. 9(b) is a diagram in use, FIG. 9(c) is a plan view in
use, and FIG. 9(d) is a perspective view in use;
[0045] FIG. 10 is a plan view in which the speakers are disposed on
a ceiling so as to surround a head of a seated listener in
correspondence with left and right external ears of the
listener;
[0046] FIG. 11 is a front view of the seated listener;
[0047] FIG. 12 is a perspective view in which a partition plate is
disposed between the left and right speakers;
[0048] FIG. 13 is a front view;
[0049] FIG. 14 is a front view in which the left and right speakers
are disposed near the partition plate;
[0050] FIG. 15 is a perspective view in which a board having
integrated therewith the speakers and the partition plate is
disposed on the ceiling so as to be movable left and right and back
and forth;
[0051] FIG. 16 is a perspective view showing an arrangement of
supporting the speakers with poles;
[0052] FIG. 17 is a perspective view in which the partition plate
for reducing crosstalk is provided between the speakers;
[0053] FIG. 18 is a perspective view showing a state in which the
speakers are mounted on a roof of a rear seat;
[0054] FIG. 19 is a plan view in which the speakers are mounted on
a center pillar and a side face of an adjoining seat;
[0055] FIG. 20 is a front view;
[0056] FIG. 21 is a block diagram showing a circuit configuration
of a crosstalk canceller;
[0057] FIG. 22 is a block diagram showing an arrangement including
a time delay part;
[0058] FIG. 23 is a block diagram showing an arrangement in which a
seated position is read out from a memory depending on the change
in the seated position;
[0059] FIG. 24 is a block diagram showing an arrangement including
a transfer characteristic measuring part;
[0060] FIG. 25 is an explanatory drawing of a transfer
characteristic measurement; and
[0061] FIG. 26 is a flow chart explaining the operation of transfer
characteristic measurement and reproduction.
BEST MODE FOR CARRYING OUT THE INVENTION
[0062] In order to explain this invention in more detail, a
description will now be made about the best mode for carrying out
this invention with reference to the accompanying drawings.
First Embodiment
[0063] FIG. 1 is a schematic diagram showing an arrangement of
speakers in a three dimensional sound field reproducing unit. Three
speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are respectively disposed
near each of the ears 2L, 2R of a listener 1. By means of signals
to be supplied to each of the speakers, the sound fields 0 near the
external ears are controlled.
[0064] FIG. 2 shows a reproducing circuit for supplying a
reproducing signal to each of the speakers 3L1, 3L2, 3L3 and 3R1,
3R2, 3R3. Referring to FIG. 2, reference numeral 4 denotes various
kinds of sound source, reference numeral 5 sound source selecting
means for switching the output of the sound source 4, reference
numeral 6 three dimensional signal processing means, and reference
numeral 7 a 6-channel (6ch) amplifier for outputting reproducing
signals to six speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3.
[0065] The sound source 4 includes a 2-channel compact disc (CD), a
5.1-channel digital versatile disk (DVD), an amplitude modulation
(AM) and frequency modulation (FM) sound source, a sound source
with a three dimensional effect for playing games, a voice guidance
for car navigation, or the like.
[0066] The three dimensional signal processing means 6 includes a
digital input part (not shown), an analog input part (not shown),
an analog/digital (A/D) converting part (not shown), a digital
signal processing part (not shown), a digital/analog (D/A)
converting part (not shown), or the like, and performs signal
processing for converting an output signal from the sound source
selecting means 5 into a three dimensional sound field signal.
[0067] In the first embodiment, there is shown a case in which
three speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are respectively
disposed for each of the left external ear and the right external
ear. The reason why this kind of arrangement is preferable is given
hereinbelow. In this case the control points (points to reproduce
in the space the state of target sound wave) lie in three points
near the respective external ears.
[0068] (1) First Reason
[0069] It is possible to produce in the control points the same
sound pressure as in the case of the original sound field. In order
to realize it, a transfer function (an impulse response as
represented by a time domain) is required from the speakers 3L1,
3L2, 3L3 and 3R1, 3R2, 3R3 to the control points.
[0070] The shorter the time of this transfer function becomes, the
smaller the scale of the hardware to perform the signal processing
becomes. Therefore, the arrangement of the speakers should be
selected so as to shorten the time as far as possible. In an
ordinary room or in a vehicle compartment, it might be said that
the shorter the distance between the speakers and the control
points is, the shorter the time of the transfer function is.
[0071] It is because that the more the speakers and the control
points away from each other, the larger the ratio of reflected
sounds arrived at the control points from all directions of the
room or the vehicle compartment becomes compared with the direct
sounds arrived directly from the speakers to the control points.
Conversely, in case the distance between the speakers and the
control points is small, there will increase the ratio of the
direct sounds arrived directly from the speakers to the control
points compared with the reflected sounds inside the room. The
amplitudes of the transfer function will thus be dominated for the
most part by the direct sounds, and the amplitude components of the
reflected sounds are extremely small as compared with the direct
sounds. Therefore, the time of the transfer function can be
regarded as the time required for converging the direct sounds.
[0072] (2) Second Reason
[0073] By making the speakers disposed on the left and right of the
head 1 of the listener close to the neighborhood of the external
ears, the ratio of crosstalk between both the ears can be reduced.
The closer the right speakers are brought to the right ear, the
larger the ratio between the sounds becomes, one of which directly
comes into the right ear and the other of which leaks to the
opposite left ear, thereby decreasing crosstalk.
[0074] If the amount of the left and right crosstalk is small, it
becomes possible to independently perform the signal processing of
the left and right sound fields when the sound fields 0 near the
external ears are controlled. The greatest advantage thereof is in
that the amount of computation is alleviated down to 1/2. The
signal processing to be performed in the three dimensional sound
field reproducing unit is proportional to the product of the number
of the speakers and that of the control points.
[0075] Now, suppose that the number of the speakers is respectively
N in the left and the right and that the number of the control
points is also respectively N in the left and the right. In case
the amount of crosstalk is small and the left and right signal
processing can be independently performed, the amount of
computation is N.times.N per one ear and 2.times.(N.times.N) for
left and right ears. In case the amount of crosstalk is large, on
the other hand, since it becomes necessary to process the left and
right signals together, the amount of computation becomes
2N.times.2N, i.e., 4.times.(N.times.N). In case there is no
crosstalk, the amount of computation goes down to 1/2.
[0076] The vehicle-mounted three dimensional sound field
reproducing unit of this invention does not necessarily coerce the
number of the speakers in the left and right to be limited to
three. Theoretically, since the control points increase in
correspondence with the number of the speakers, the larger the
number of the speakers becomes, the more the original sound field
is accurately simulated. However, since the amount of signal
processing is proportional to the second power of the number of the
speakers, the unit having an unreasonably large number of speakers
is not practical when the number of the channels and the capacity
of computation processing in an ordinary audio device are
considered.
[0077] When considered from the viewpoint of simulation accuracy,
on the other hand, disposing one speaker on the left and right side
respectively shows little or no difference from the conventional
headphone system. Therefore, the reasonable choice will therefore
be at least more than two speakers for each ear. This technique of
using two speakers for each ear is, however, insufficient in
accuracy because the sound field can only be reproduced along the
line connecting the two control points.
[0078] In case three speakers are used for each ear, the sound
field can be reproduced within the region of a triangle formed by
connecting the three control points. In this case, it is possible
to reproduce even the travelling direction of the sound waves
within the region by reproducing the sound pressure at the control
points. In order to perceive the three dimensional
(three-dimensional) sound field, it is highly important that the
travelling direction of the sound waves is reproduced. Considering
the direction of propagation of the sound waves, the number of the
speakers with which one expects to reproduce the sound field with
high accurate and which does not amount to a large scale for
practical use will be three in the left and right respectively,
i.e., six in total.
[0079] FIG. 3 is a schematic diagram in which a vehicle-mounted
three dimensional sound field reproducing unit is disposed in a
front passenger's seat in an ordinary vehicle. FIG. 4 is an
enlarged side view of a headrest of the front passenger's seat.
FIG. 5 is a front view thereof, in which speakers 3L1, 3L2, 3L3 and
3R1, 3R2, 3R3 are disposed in a headrest 9 projecting from an upper
surface of a backrest 8 of the seat.
[0080] In FIGS. 3 and 4, the signal outputted from the sound source
4 is selected by the sound source selecting means 5 and subjected
to signal processing by the three dimensional signal processing
means 6 depending on the sound source 4, thereby outputting analog
signals equal to the number of the speakers (FIG. 4 is an example
of 6 channels).
[0081] The signal outputted from the three dimensional signal
processing means 6 is amplified by the 6-channel amplifier 7 to a
level required for listening and are inputted to each of the six
speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 which are built in the
headrest 9. The speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are
respectively disposed by distributing them in the left and right
with the head of the listener 1 sandwiched therebetween. The
speakers 3L1, 3L2, 3L3 reproduce the sound field near the left ear
of the listener 1 and the speakers 3R1, 3R2, 3R3 reproduce the
sound field near the right ear.
[0082] As described above, according to the first embodiment, the
speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are disposed in the
headrest 9 on the backrest 8 that is present closest to the head 1
and the external ears of the listener 1. Therefore, the head 1 of
the listener is positioned between the left and right speakers 3L1,
3L2, 3L3 and 3R1, 3R2, 3R3, thereby shortening the distance to the
control points. As a result, an ideal audible region is generated
between the left and right speakers, which reduces crosstalk.
Second Embodiment
[0083] FIGS. 7(a) and 7(b) are diagrams showing an embodiment in
which an attempt is made to reduce crosstalk between the left and
right speakers and in which a pair of left and right recessed
portions 9L, 9R are formed in a front of the headrest 9 so that the
speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are buried deep into the
head rest 9 in a position sequestered from the surface of the
recessed portions 9L, 9R.
[0084] Having been arranged as above, in case the speakers are
disposed on the face of the headrest 8, the distribution of sounds
radiated from the speakers extends as shown in FIG. 6, thus
generating a region in which a large quantity of crosstalk occurs.
On the other hand, if the speakers are buried deep into the
headrest 9 as with the second embodiment, the distribution of
sounds radiated from the speakers will be as shown in FIG. 8,
whereby the region in which a large amount of crosstalk occurs can
be made smaller than the arrangement shown in FIG. 6.
[0085] As described above, according to the second embodiment, the
occurrence of crosstalk in the left and right speakers can surely
be reduced.
Third Embodiment
[0086] FIGS. 9(a) through 9(d) are diagrams showing an arrangement
according to the third embodiment, wherein FIG. 9(a) is a side
view, FIG. 9(b) is a side view in a state in which the speakers are
in use, FIG. 9(c) is a plan view of FIG. 9(b), and FIG. 9(d) is a
perspective view of FIG. 9(b). As shown in FIGS. 9(a) through 9(d),
the speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are housed inside the
headrest 9 so that they can be pulled out for use when necessary.
The left and right speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are
respectively housed in a small boxes 10L, 10R, and these boxes 10L,
10R are retractably housed into recessed portions 9L, 9R in the
headrest 9 so that, when not in use, the boxes 10L, 10R are housed
into the recessed portions 9L, 9R and, when in use, the boxes 10L,
10R are pulled out of the recessed portions 9L, 9R in the headrest
9.
[0087] As described above, according to the third embodiment, by
housing the speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 inside the
boxes 10L, 10R which are retractably arranged into, and pulled out
of, the recessed portions 9L, 9R in the headrest 9, the speakers
can be disposed in positions closer to the external ears. As a
result, this offers an advantage that a listening state is obtained
which is akin to a state where an ideal headphone is worn by the
listener, and that the boxes 10L, 10R does not interfere by housing
them into the recessed portions 9L, 9R when not in use.
Fourth Embodiment
[0088] FIG. 10 is a plan view showing an embodiment in which the
speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are buried into a ceiling
surface 11 of a vehicle, and FIG. 11 is a front view thereof. The
speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 are disposed on the
ceiling surface 11 of the vehicle so as to surround the head 1.
[0089] As described above, according to the fourth embodiment, the
distance from the ceiling surface 11 of the vehicle to the head 1
of the listener is small, and a more freedom in the disposition of
the speakers can be won than the headrest 9.
Fifth Embodiment
[0090] Only disposing the speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3
on the ceiling surface 11 of the vehicle as shown in FIGS. 10 and
11 fails to get rid of a danger that crosstalk level of the left
and right speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 would become
high. In order to solve this problem, in the fifth embodiment,
there is provided a partition plate 12, as shown in the perspective
view of FIG. 12 and in the front view of FIG. 13, between the
speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 disposed in the left and
right so as to sandwich the head 1.
[0091] As described above, according to the fifth embodiment, it is
possible to realize the reduction in crosstalk between the left and
right speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 as shown in FIGS. 12
and 13.
Sixth Embodiment
[0092] FIG. 14 is a schematic diagram showing an arrangement for
further reducing crosstalk. The left and right speakers 3L1, 3L2,
3L3 and 3R1, 3R2, 3R3 are disposed close to the partition plate 12
so that the direction of the sounds radiated from each of the
speakers is directed to the respective ears.
[0093] As described above, according to the sixth embodiment, the
level indicative of the direct sounds radiated from the right
speakers 3R1, 3R2, 3R3 come into the left ear and the level
indicative of the direct sounds radiated from the left speakers
3L1, 3L2, 3L3 come into the right ear are respectively decreased. A
further reduction in crosstalk thus becomes possible.
Seventh Embodiment
[0094] FIG. 15 is a perspective view in which the speakers 3L1,
3L2, 3L3 and 3R1, 3R2, 3R3 and the partition plate 12 are
integrally mounted on a board 13 in the shape of a single piece of
plate, and are disposed on the ceiling 11 of the vehicle so as to
be movable back and forth and left and right by means of a rail
structure (not shown).
[0095] As described above, according to the seventh embodiment,
even if there happed to move the seat in the back and forth
direction or the head of the listener 1, the speakers 3L1, 3L2, 3L3
and 3R1, 3R2, 3R3 and the partition plate 12 can be disposed in a
most appropriate position, which ensures at all times an ideal
sound effect.
Eight Embodiment
[0096] FIG. 16 is a perspective view in which, in case a seat
itself such as a front seat of a vehicle is movable in the back and
forth direction, wherein the module is made up of pole parts 15
through 17 which adjustably support speaker mounting parts 14L, 14R
provided in the left and right of the head of the listener 1 and
which have sliding structure and are flexibly connected to one
another; and a base 18 which supports a base end of the pole 17.
The base 18 for supporting the base end of the pole 17 is of a
structure to allow the pole part 17 to incline in an arbitrary
direction.
[0097] As described above, according to the eight embodiment, even
if there happed to move the seat in the back and forth direction,
it is possible to maintain the positional relationship between the
speaker mounting parts 14L, 14R and the head of the listener 1. In
addition, the pole 15 has a sliding structure in a portion to which
the left and right speaker mounting parts 14L, 14R are connected
together. This permits an adjustment of the distance between the
left and right speaker mounting parts in correspondence with the
size of the head of the listener 1. The poles 16, 17 have sliding
structures in the back and forth direction and in the vertical
direction, respectively. This enables a fine adjustment of the
positional relationship between the speaker mounting parts 14L, 14R
and the head.
Ninth Embodiment
[0098] FIG. 17 a perspective view in which the partition plate 12
for reducing crosstalk between the left and right speakers is
rotatably provided in an intermediate of the pole 15 which supports
the left and right speaker supporting parts 14L, 14R.
[0099] As described above, according to the ninth embodiment, it
efficiently reduces crosstalk by the partition plate 12 and, when
not necessary, the partition plate 12 can be rotated in a
non-interfering rearward position.
Tenth Embodiment
[0100] FIG. 18 a perspective view in which, in case a seat such as
a rear seat 19 does not move in the back and forth direction, the
base 18 of a sliding structure as shown in FIG. 16 is fixed to a
rear tray or to a rear shelf 20 on the rear seat 19.
[0101] As described above, according to the tenth embodiment, even
in case the seat 19 does not move in the back and forth direction,
the sliding structure of the poles 15 through 17 allows a fine
adjustment of the positional relationship between the speaker
mounting parts 14L, 14R and the head.
Eleventh Embodiment
[0102] FIG. 19 is a plan view showing the eleventh embodiment in
which speakers 3L1, 3L2, 3L3 are disposed on a pillar which is
positioned substantially in the center in front and in rear inside
a vehicle compartment, and speakers 3R1, 3R2, 3R3 are disposed on a
side of an adjacent seat. FIG. 20 is a front view of the
arrangement of the speakers 3L1, 3L2, 3L3 and 3R1, 3R2, 3R3 in FIG.
19 as viewed from the front of the vehicle.
[0103] Referring to FIGS. 19 and 20, reference numeral 21 denotes a
driver's seat, reference numeral 22 a front passenger's seat, and
reference numeral 23 the pillar positioned substantially in the
center in front and in rear on the left side of the vehicle
compartment. Like reference numerals as FIG. 2 indicated like
components and therefore descriptions thereof are omitted for
brevity's sake. As the sound source 4, an audio reproducing unit
such as a CD player or the like is exemplified. Since the switching
of the sound source 4 is not particularly required, the sound
source selecting means 5 shown in FIG. 2 is omitted in FIGS. 19 and
20.
[0104] The three dimensional signal processing means 6 includes an
inverse transfer characteristic Hspl for the left-channel speakers;
head transfer function H11, H12, H13 from the left-channel speakers
to the speakers 3L1, 3L2, 3L3 disposed near the left ear; a
crosstalk canceller 24 as a signal processing part for canceling
crosstalk between speakers 3L1 and 3L2, between speakers 3L2 and
3L3, and between speakers 3L3 and 3L1; an inverse transfer
characteristic Hspr for the right-channel speakers; head transfer
function Hr1, Hr2, Hr3 from the right-channel speakers to the
speakers 3R1, 3R2, 3R3 disposed near the right ear; a crosstalk
canceller 25 as a signal processing part for canceling crosstalk
between speakers 3R1 and 3R2, between speakers 3R2 and 3R3, and
between speakers 3R3 and 3R1.
[0105] The inverse transfer function Hsp1 for a given left-channel
speaker is convoluted for the left-channel signal of the audio
reproducing unit as the sound source 4 to correct characteristic of
the given speaker. The inverse transfer function Hspr for a given
right-channel speaker is convoluted for the right-channel signal of
the audio reproducing unit to correct characteristic of the given
speaker.
[0106] FIG. 21 is a block diagram showing a circuit configuration
of the crosstalk canceller 24 (25).
[0107] A description will now be given to the operation of the
crosstalk cancellers 24 of the eleventh embodiment.
[0108] As a technique for causing a listener to feel as if he/she
were listening to the music in a given space, there is a technique
in which the sound pressure, phase and particle velocity near the
left and right ears are maintained in the same state as in the case
of the given space. When the speakers are disposed near both the
ears and a reproducing signal which is subjected to a predetermined
signal processing is reproduced through the speakers, the sound
pressure, phase and particle velocity can be reproduced within the
limits of both the ears, without being influenced by the acoustic
characteristics in the entire space.
[0109] The signal radiated from the speaker 3L1 forms a sound
pressure component and a phase component in the space near the left
ear. The sound waves radiated from the speaker 3L2 excise an
influence upon the speaker 3L1 and disturbs its sound waves.
Therefore, the sound pressure component, phase component, and
particle velocity in the space near the left ear do not attain a
predetermined state.
[0110] CLl2 in the crosstalk canceller 24 prevents the signal
disturbance of the speaker 3L1 by previously adding an inverse
characteristic of the component to be disturbed by the speaker 3L2
to the signal of the speaker 3L2. The disturbance between the
speakers 3L1 and 3L3 is corrected by crosstalk CLl3. The same holds
true for the signals of the remaining speakers 3L2, 3L3 in the left
channel. Regarding the right-channel signal, a similar signal
correction is performed by the crosstalk canceller 25 which has the
same configuration as the crosstalk canceller 24.
[0111] As described above, according to the eleventh embodiment,
since the speakers are mounted on the pillar and the adjacent seat,
a larger space can be secured for mounting the speakers and a large
back-cavity space can be secured. More freedom can be won for
choice of the type of speakers, which secures a reproducing sound
pressure response where lower bass is reproducible.
Twelfth Embodiment
[0112] FIG. 22 is an arrangement for correcting by a delay
processing part the time delay due to the difference in distance in
a case where the position of a seat is adjusted more forward than
FIG. 19, or in a case where the seat is adjusted in the backward or
the vertical direction, or the reclining angle of the backrest,
whereby the distances from the speakers to the ears of the listener
1 becomes larger. In FIG. 22, reference characters Delay L denote a
time delay part for correcting the time delay due to the difference
in distance in an array of the left speakers, and reference
characters Delay R a time delay part for correcting the time delay
due to the difference in distance in an array of the right
speakers. The other arrangement is the same as with the tenth
embodiment shown in FIG. 19. Therefore, like reference numerals
indicate like components and descriptions thereof are omitted for
brevity's sake.
[0113] According to the above arrangement, when the head of the
listener 1 gets out of positions of the left and right speakers
3L1, 3L2, 3L3 and 3R1, 3R2, 3R3, a difference is made in the head
transfer function and the crosstalk canceling component. The
influence of time delay due to geometric difference in distance is,
however, corrected by the time delay part.
[0114] As described above, according to the twelfth embodiment, the
change in distance between the speakers and the external ears can
be corrected by the time delay parts Delay L, Delay R, which
appropriately cancels the crosstalk.
Thirteenth Embodiment
[0115] As shown in FIG. 23, the thirteenth embodiment includes a
seated position control part 27 which, interlocked with the seated
position, reads out the seated position information from a seated
position memory 26; and a convolution coefficient control part 29
which reads out a convolution coefficient from a convolution
coefficient memory 28 based on the output of the seated position
control part 27 to send it to the three dimensional signal
processing means 6. The other structure is the same as with the
tenth embodiment shown in FIG. 19. Therefore, like reference
numerals indicate like components and descriptions thereof are
omitted for brevity's sake.
[0116] A description will now be given to the operation of the
thirteenth embodiment.
[0117] The convolution coefficient memory 28 has stored therein,
for each of the predetermined positions of the seated seat, a
convolution coefficient in which the head transfer function and the
crosstalk canceling component have been measured in advance. The
coefficient of the position closest to the seated seat is read out
to supply it to the three dimensional signal processing means 6. It
is thus possible to supply to the speakers the output signal having
paid due consideration to the head transfer function and the
crosstalk canceling component corresponding to the seated position
from the three dimensional signal processing means 6 through the
6-channel amplifier 7.
[0118] As described above, according to the thirteenth embodiment,
it reduces crosstalk good for the position of the occupied
seat.
Fourteenth Embodiment
[0119] FIG. 24 is a block diagram showing the fourteenth embodiment
in which the difference in the head transfer function due to the
seated seat is measured by microphones ML1 through ML3 and MR1
through MR3 disposed in the headrest, and a convolution coefficient
is obtained for storing it. A transfer characteristic measuring
part 33 is provided which reads out a convolution coefficient from
the convolution coefficient memory 31 depending on the seated
position and supplies it to the convolution coefficient control
part 32. The other arrangement is the same as with the eleventh
embodiment shown in FIG. 19. Therefore, like reference numerals
indicate like components and descriptions thereof are omitted for
brevity's sake.
[0120] FIG. 25 is an explanatory drawing showing how to find the
convolution coefficient. Referring to FIG. 25, reference character
ML3 denotes a front microphone mounted on the left side of the
headrest, reference character ML1 a rear microphone mounted on the
left side of the headrest, and reference character ML2 a microphone
positioned between the microphones ML1 and ML3. Similarly,
reference characters MR1, MR2, MR3 denote microphones mounted on
the right side of the headrest. Reference characters ML1A through
ML3A and MR1A through MR3A respectively denote preamplifiers for
the microphones ML1 through ML3 and MR1 through MR3. Reference
characters 3L1 through 3L3 and 3R1 through 3R3 respectively denote
the above-described speakers.
[0121] Reference character Gl1-ml1 denotes a transfer function
between the speaker 3L1 and the microphone ML1, reference character
Gl1-ml2 a transfer function between the speaker 3L1 and the
microphone ML2, reference character Gl1-ml3 a transfer function
between the speaker 3L1 and the microphone ML3, reference character
Gr1-mr1 a transfer function between the right speaker 3R1 and the
microphone MR1, reference character Gr1-mr2 a transfer function
between the right speaker 3R1 and the microphone MR2, and reference
character Gr1-mr3 a transfer function between the right speaker 3R1
and the microphone MR3.
[0122] Then, a description will be given to the measurement of the
convolution coefficient with reference to the flow chart in FIG.
26. When a measurement starts, switch 34 is turned on, a white
noise signal is generated from the 6-channel amplifier 7 and is
radiated from the speaker 3L1. The sound waves of the radiated
white noise are collected by the microphones ML1, ML2, ML3, are
passed through the preamplifiers ML1A, ML2A, ML3A, and are inputted
to the transfer characteristic measuring part 33 (step ST1).
[0123] The transfer characteristic measuring part 33 obtains a
transfer function from the original white noise signal and the
signal collected by the microphone ML1. For example, the white
noise and the microphone signal are subjected to discrete Fourier
transform, and a transfer function is obtained by the ratio
thereof. The inverse transfer function of the transfer function is
CLl1 in the crosstalk canceller 24 (step ST2).
[0124] From the white noise signal and the signal collected by the
microphone ML2, CL21 can be obtained, and from the white noise
signal and the signal collected by the microphone ML3, CL31 can be
obtained. The white noise is reproduced from the speaker 3L2, and
CL22 is obtained by the signal collected by the microphone ML1, and
CL22 can be obtained by the signal collected by the microphone ML2,
and CL32 can be obtained by the signal collected by the microphone
ML3. The same holds true for the speaker 3L3. Measurement is
similarly made with respect to the right speakers 3R1 through 3R3
(step ST3). The measured inverse transfer function is stored in the
convolution function memory 31 as the convolution function (step
ST4).
[0125] At the time of reproduction, the convolution function is
read out from the convolution function memory 31 and is transferred
to the three dimensional signal processing means 6 through the
convolution function control part 32 (step ST5). The coefficient is
convoluted into the audio signal from the sound source 4 (step ST6)
and is transferred to the 6-channel amplifier 7 after D/A
conversion (step ST7).
[0126] As described above, according to the fourteenth embodiment,
the difference in the head transfer function produced depending on
the position of the seated seat is measured by the microphones ML1
through ML3 and MR1 through MR3 disposed in the headrest 9, and a
convolution function is obtained for storing it in the function
memory 31. At the time of reproduction, the convolution function is
read out from the convolution function memory 31, and is reproduced
by transmitting it to the three dimensional signal processing means
6. Therefore, it is possible to generate at all times a three
dimensional sound field reproducing space good for the head of the
listener.
[0127] In the thirteenth and fourteenth embodiments a reference is
made to the passenger on the front left seat. Similar effect can
also be obtained for the driver seated on the front right seat by
disposing the speaker arrays on the right-side pillar and on the
side surface of the front left seat inside the vehicle
compartment.
[0128] In addition, regarding the speakers disposed on the ceiling
shown in FIG. 11, similar effect can also be obtained.
INDUSTRIAL APPLICABILITY
[0129] As described above, the three dimensional sound field
reproducing unit according to this invention is qualified for
making the listener enjoyed perceiving a three dimensional sound
field with rich presence.
* * * * *