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JP2001346297

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DESCRIPTION JP2001346297
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
sound image reproduction system.
[0002]
2. Description of the Related Art Conventionally, as a system for moving a sound image left and
right, for example, a two-channel stereo system as shown in FIG. 7 is known. The sound source
signal input to this system is distributed to the amplifiers 711 and 712 by the variable
distributor 701, and the speakers 721 and 722 are driven by the amplifiers 711 and 712
according to the level distribution by the variable distributor 701, respectively. Therefore, the
sense of direction of the sound image changes to the left and right according to the level
distribution of the left and right speaker inputs.
[0003]
On the other hand, as a system for controlling the sense of distance, for example, the one
described in JP-A-9-121400 is known. The system described in Japanese Patent Laid-Open No. 9121400 is configured as shown in FIG. 8 in which the speaker array 841 is disposed in space,
and the delay elements constituting the delay unit 811 have the respective delay amounts of the
speaker array 841. The sound wave from each of the speakers constituting the speaker is set as a
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direct sound to focus on one point in space, while the delay element constituting the delay unit
812 is such that each delay amount is from each speaker constituting the speaker array 841 The
sound wave of is set so as not to focus on a point in space as an indirect sound.
[0004]
The sound source signal input to this system is level-distributed by the variable distributor 801,
supplied to the delay units 811, 812, and the sound source signals from the delay elements
forming the pairs of the delay units 811, 812 are added together. The obtained sound source
signals are respectively added by the adders that make up the signal, and the obtained sound
source signals are respectively amplified by the amplifiers that make up the amplifier 831, and
the corresponding speakers of the speaker array 841 are driven by the respective amplifiers.
[0005]
Therefore, according to the level ratio of the sound source signal, the ratio of the strength of the
direct sound to the indirect sound changes, and as a result, the sense of distance of the sound
image is controlled from the listening point E in FIG. It will be
[0006]
Therefore, by combining such techniques for controlling the sense of localization of the sound
image in the left and right or depth direction, a plurality of sound images are localized at a
predetermined point on a plane centered on the listener. It is possible to do it.
In that case, position information consisting of different distances and directions are provided for
each of a plurality of sound source signals and presented as separate sound images, and
moreover, they are made to change with time. It is necessary to provide auxiliary information
constantly in synchronization.
As such auxiliary information, various information can be considered, including two-dimensional
position information, information in the height direction, and which side the sound source itself
is facing, equivalent to the amount of information required for the sound source information or It
is necessary to add more information. In addition, as the number of sound sources increases,
there is a problem that the amount of information required for recording and transmission of
voice becomes extremely large.
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[0007]
The object of the present invention is a sound image reproduction system capable of solving the
above problems and preventing an increase in transmission capacity with an increase in the
number of sound images while maintaining a sense of reality such as localization of sound
images. It is to provide.
[0008]
The invention according to claim 1 is a speaker array disposed in a space, and a first delay means
for delaying one signal, wherein the sound waves from the respective speakers of the speaker
array are direct sounds. A first delay means having a delay element whose delay amount is set to
focus on one point of space, and a second delay means for delaying the other signal, wherein the
sound waves from the respective speakers of the speaker array are indirect Addition means for
adding signals from the second delay means having delay elements whose delay amounts are set
so as not to focus on one point in space as sound, and signals from the delay elements to be
paired with the first and second delay means And in the sound image reproduction system
having the drive means for driving the speaker array based on the signal obtained by the
addition by the addition means, the level difference and the distance sense area number are
made to correspond. A storing means for storing a bell difference vs. distance feeling area
number table, an extracting means for extracting a level difference corresponding to the received
distance feeling area number from the level difference vs. distance feeling area number table of
the storing means, and the extracting means Holding means for holding the extracted level
difference, and distribution means for distributing the level ratio of the decoded sound source
signal to the first and second delay means in accordance with the level difference held by the
holding means It is characterized by having.
[0009]
According to the first aspect of the present invention, the take-out means can receive the sense of
distance area number sent out when the input level difference changes and exceeds the
discrimination limit.
[0010]
The invention of claim 3 is a first means comprising the speaker array according to claim 1, the
first delay means, the second delay means, the adding means, and the driving means, and the
speaker array according to claim 1 and the first means. Store a level difference vs. left-right
distance sense area number table in which the left-right direction level difference and the leftright direction distance sense area number are associated with the second means having the
delay means, the second delay means, the addition means, and the drive means Left / right
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direction storing means and left / right direction extracting means for taking out the left / right
direction level difference corresponding to the received left / right direction distance feeling area
number from the level difference of the left / right direction storing means vs. left / right
direction distance feeling area number table And the horizontal direction holding means for
holding the horizontal direction level difference extracted by the horizontal direction extraction
means, and the horizontal direction holding means for holding the level ratio of the decoded
sound source signal. Depth that stores the level difference vs. depth direction distance sense area
number table in which the horizontal direction distribution means, which distributes according to
the left / right direction level difference, and the depth direction level difference and the depth
direction distance sense area number Store means for direction, depth direction pick-up means
for taking out the depth direction level difference corresponding to the received depth direction
distance sense area number from the level difference vs depth direction distance sense area
number table of the depth direction store means, The depth ratio holding means for holding the
depth direction level difference extracted by the depth direction extraction means, and the level
ratio of each sound source signal having the level ratio distributed by the left and right direction
distribution means First distributing means for distributing to the first and second delaying
means of the first means according to the depth direction level difference held by the second
holding means; And it is characterized in that a second distribution means for distributing the
second delay means.
[0011]
According to the third aspect of the present invention, the left-right direction extraction means
can receive the left-right distance sense area number sent out when the input level difference
changes and exceeds the discrimination limit.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
[0013]
First Embodiment FIG. 1 shows a first embodiment of the present invention.
This is an example of a sound image reproduction system that controls the sense of distance of a
sound image.
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[0014]
The inventor of the present invention has found that the perception of distance and direction of a
sound image does not require infinite precision, but only finite precision is perceived.
Therefore, in the present embodiment, only the minimum necessary information is used to
control the direction of the sound image and the sense of distance based on the auditory
discrimination limit.
[0015]
FIG. 1 will be described.
In FIG. 1, 811, 812, 821, 831 and 841 indicate the same parts as FIG. 8.
A drive control unit 5 drives and controls the speaker array 841. The drive control unit 5
includes delay units 811 and 812, an addition unit 821, and an amplifier 831, and is variable
instead of the variable distributor 801 of FIG. A distributor 101 is provided.
The variable distributor 101 can change the distribution ratio according to the level difference
signal.
The delay elements constituting the delay unit 811 are set such that each delay amount focuses
the sound wave from each speaker constituting the speaker array 841 as a direct sound at one
point in space, while the delay unit 812 The delay elements are set such that the amounts of
delay do not cause the sound waves from the speakers constituting the speaker array 841 to be
focused at one point in space as indirect sound.
[0016]
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A sound source coder 1 compresses the sound source signal with high efficiency. A sound source
decoder 2 decompresses the sound source signal compressed by the sound source encoder 1
with high efficiency, reproduces the sound source signal as a sound source signal, and supplies it
to the variable distributor 101.
[0017]
Reference numeral 3 denotes a transmission side distance control unit, which includes a distance
to level difference converter 301, a level difference to area number converter 302, and a level
difference to distance area number table 303. The distance-to-level difference converter 301
converts a presentation distance signal of an input sound image into a level difference signal. The
level difference signal is previously adjusted so that the sound image is at a predetermined
position when the level difference signal is used for level control of the variable distributor 101.
The level difference to area number converter 302 converts the level difference signal from the
distance to level difference converter 301 into a distance area number with reference to the level
difference to distance area number table 303, and the receiving side distance control unit
Transfer to 4). This transfer is not continuous, but is sent when the input level difference changes
and the discrimination limit is exceeded. It is determined with reference to the level difference vs.
distance area number table 303 that the discrimination limit is exceeded.
[0018]
Reference numeral 4 denotes a receiving side distance control unit, which includes an area
number to level difference converter 401, a level difference to distance feeling area number table
402, and a level difference holder 403. The area number to level difference converter 401
converts the distance sense area number from the sending side distance control unit 3 into a
level difference signal with reference to the level difference to distance sense area number table
402. The level difference holder 403 holds the level difference signal from the area number to
level difference converter 401 until the next distance sense area number is received, and uses it
for the level control of the variable distributor 101.
[0019]
Next, the level difference-to-feeling area number tables 303 and 402 will be described. First, in
order to divide the presentation distance of the sound image into regions according to the
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discrimination for each sense of distance and assign numbers, as shown in FIG. 2, the distribution
level of the sound source signal by the variable distributor 101 is controlled according to the
level difference signal. When the difference in distance between the two presented sound images
A and B can not be perceived, the maximum distance among the distances between A and B is
used as the discrimination limit.
[0020]
The presentation distance referred to here is a subjective distance, which is very far (+3), far (+2),
somewhat far (+1), unknown (0), somewhat near (-1), close (-2), It calculated ¦ required by the
evaluation experiment by 10 graders by making very near (-3) into a scale.
[0021]
The displays 1, 2, 3, 4, 5 and 6 of the level difference signal of FIG. 3 are respectively 1.0, 0.8,
and 1.0 of the gain of the signal distributed to the delay unit 811 by the variable distributor 101
of FIG. It corresponds to 0.6, 0.2 and 0.0.
At this time, the gain of the signal distributed to the delay unit 812 is such that the sum of
squares of the respective signals to the delay units 811 and 812 is always 1. For this, refer to the
reference: Koizumi et al .: "Study on distance control parameter of sound image using speaker
array", Technical Bulletin EA-98-31 (1998).
[0022]
The relationship between the presentation distance and the level difference signal determined in
this manner is, for example, as shown in FIG. Also, the relationship between the level difference
signal and the number of the area in which the sound image is presented is as shown in FIG. 4,
for example.
[0023]
Then, the level difference and the area number thus obtained are made to correspond to each
other to create a level difference vs. distance area number table.
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[0024]
According to the inventor's experiments, only a few dozen discrete values are used as control
information for each perception of direction and distance, and the effect is sufficient if the
position of the sound image is controlled. there were.
[0025]
The operation of the system of FIG. 1 will now be described.
The sound source signal is highly efficiently compressed by the sound source encoder 1 and
transferred to the sound source decoder 2.
In the sound source decoder 2, the signal received from the sound source encoder 1 is
decompressed and reproduced as a sound source signal and supplied to the variable distributor
101.
[0026]
On the other hand, the presentation distance signal is converted into a level difference signal by
distance-to-level difference converter 301 of transmission side distance control section 3, and the
level difference signal obtained is converted by level difference-to-area number converter 302.
With reference to the area number table 303, the area number table is converted into a distance
feeling area number, and transferred to the reception side distance control unit 4. This transfer is
not continuous, but is sent when the input level difference changes and the discrimination limit is
exceeded. Exceeding the discrimination limit is determined with reference to the level difference
/ distance feeling area number table 303.
[0027]
The distance feeling area number received by the area number to level difference converter 401
of the reception side distance control unit 4 is a level difference signal with reference to the level
difference to distance feeling area number table 402 by the area number to level difference
converter 401. The level difference signal converted and obtained is held by the level difference
holder 403 until the next distance sense area number is received, for use in level control of the
variable distributor 101.
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[0028]
The sound source signal supplied from the sound source decoder 2 to the variable distributor
101 is level-distributed by the variable distributor 101 according to the level difference signal
from the level difference holder 403, and supplied to the delay units 811 and 812 respectively.
The sound source signals from the delay elements forming the pair of delay units 811 and 812
are respectively added by the adder configuring the adding unit 821, and the obtained sound
source signals are amplified by the amplifiers configuring the amplifying unit 831, respectively.
The amplifiers drive the corresponding speakers of the speaker array 841.
[0029]
As described above, the level control is performed not discretely but discretely, but since the
level difference signal of change is selected below the auditory discrimination limit, it is felt as
substantially continuous change, and the sound image is Sense of distance can be controlled from
the distance to the position of the focal point.
Therefore, even if the number of sound images increases, the transmission capacity can be
reduced, and furthermore, the sense of reality such as the localization of the sound images can be
maintained.
[0030]
Second Embodiment FIG. 5 shows a second embodiment of the present invention.
This is an example of a sound image reproduction system that controls the directionality of a
sound image. In FIG. 5, reference numerals 5, 101, 811, 812, 821, 831, 841 denote the same
parts as in FIG. In this system, two sets of drive control unit 5 and speaker array 841 are used,
and transmission-side distance control unit 503 and reception-side distance control unit 504 are
respectively the transmission-side distance control unit 3 and the reception-side distance in FIG.
The control unit 4 has the same function as the control unit 4, and the level difference signal of
the reception-side distance control unit 504 is supplied to each of the variable distributors 101
of the two drive control units 5.
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[0031]
Reference numeral 501 denotes a sound source encoder, and reference numeral 502 denotes a
sound source decoder, each having the same function as the sound source encoder 1 and the
sound source decoder 2 of FIG.
[0032]
Reference numeral 506 denotes a sending side direction control unit, which includes a direction
to level difference converter 5061, a level difference to area number converter 5062, and a level
difference to direction area number table 5063.
The direction-to-level difference converter 5061 converts a presentation direction signal of an
input sound image into a level difference signal. The level difference signal is previously adjusted
so that the sound image is at a predetermined position when the level difference signal is used
for level control of the variable distributor 101. The level difference to area number converter
5062 converts the level difference signal from the direction to level difference converter 5061
into a direction sense area number with reference to the level difference to direction sense area
number table 5063, and the receiving side direction control unit It is to be transferred to 507.
This transfer is not continuous, but is sent when the input level difference changes and the
discrimination limit is exceeded. It is determined with reference to the level difference vs.
directional area number table 5063 that the discrimination limit has been exceeded.
[0033]
A reception side direction control unit 507 includes an area number to level difference converter
5071, a level difference to direction sense area number table 5072, and a level difference holder
5073. The area number to level difference converter 5071 converts the direction sense area
number from the sending side direction control unit 506 into a level difference signal with
reference to the level difference to direction sense area number table 5072. Level difference
holder 5073 holds the level difference signal from area number to level difference converter
5071 until the next directional sense area number is received, and uses it for level control of
variable distributor 509.
[0034]
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Reference numeral 509 denotes a variable distributor, which distributes the levels of the sound
source signal from the sound source decoder 502 in accordance with the level difference signal
from the level difference holder 5073 of the reception side direction control unit 507, and drives
each of two sets. The variable distributor 101 of the control unit 5 is supplied.
[0035]
Next, the level difference vs. direction sense area number tables 5063 and 5072 will be
described.
First, since the presentation direction of the sound image is divided into areas and numbered
according to the discrimination limit for each sense of direction, the distribution level of the
sound source signal by the variable distributor 509 is controlled according to the level difference
signal as shown in FIG. And the largest angle of the angles between C and D when the difference
in the directionality of the presented two sound images C and D can not be perceived as the
discrimination limit.
[0036]
The presentation direction referred to here is a subjective direction, which is not clear (0),
slightly right (+1), right (+2), further right (+3), not clear (0), slightly left (-1) ), Left (-2), and left (3) were used as the scale, and it was determined in an evaluation experiment by 10 graders.
[0037]
In this way, the relationship between the level difference signal and the presentation direction is
determined, and the relationship between the level difference signal and the number of the area
in which the sound image is presented is determined.
Then, the level difference and the area number obtained in this way are associated with each
other to create a level difference vs. direction area number table.
[0038]
According to the inventor's experiments, only a few dozen discrete values are used as control
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information for each perception of direction and sense of direction, and the effect is sufficient if
the position of the sound image is controlled. there were.
[0039]
The operation of the system of FIG. 5 will now be described.
The sound source signal is highly efficiently compressed by the sound source encoder 501 and
transferred to the sound source decoder 502. In the sound source decoder 502, the signal
received from the sound source encoder 501 is decompressed and reproduced as a sound source
signal, and is supplied to the variable distributor 509.
[0040]
The presentation distance signal is converted to a level difference signal in the transmission side
distance control unit 503, and the obtained level difference signal is converted to a distance
feeling area number with reference to the level difference to distance feeling area number table,
and the reception side distance control It is transferred to the part 504. This transfer is not
continuous, but is sent when the input level difference changes and the discrimination limit is
exceeded. Exceeding the discrimination limit is determined by referring to the level difference /
distance feeling area number table.
[0041]
The distance sense area number received by the reception side distance control unit 504 is
converted into a level difference signal with reference to the level difference vs. distance sense
area number table, and the obtained level difference signal is obtained by the two drive control
units 5. In order to use it for level control of the variable distributor 101, it is held until the next
distance sense area number is received.
[0042]
On the other hand, the presentation direction signal is converted into a level difference signal by
the direction-to-level difference converter 5061 of the transmission side direction control unit
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506, and the level difference signal obtained is converted by the level difference to area number
converter 5062 With reference to the area number table 5063, it is converted into a directionsensitive area number and transferred to the reception side direction control unit 507.
This transfer is not continuous, but is sent when the input level difference changes and the
discrimination limit is exceeded. Exceeding the discrimination limit is determined with reference
to the level difference vs. directional area number table 5063.
[0043]
The direction-sensitive area number received by the area-number-to-level difference converter
5071 of the receiving-side direction control unit 507 is leveled by the area-number-to-level
difference converter 5071 with reference to the level-difference-direction-sensitive area number
table 5072. The level difference signal converted into a difference signal and obtained is held by
the level difference holder 5073 until the next direction-sensitive area number is received, for
use in level control of the variable distributor 509.
[0044]
The sound source signal supplied from the sound source decoder 502 to the variable distributor
509 is level-distributed by the variable distributor 509 according to the level difference signal
from the level difference holder 5073 and each of the two sets of the drive control unit 5 is The
sound source signals are supplied to the variable distributor 101, and in each drive control unit
5, the sound source signals from the delay elements forming the pair of the delay units 811 and
812 are respectively added by the adder constituting the adding unit 821 The signals are
respectively amplified by the amplifiers constituting the amplification unit 831, and the
corresponding speakers of the speaker array 841 are driven by the respective amplifiers.
[0045]
Since it comprised in this way, two sound images localized by a predetermined angle are changed
to the left-right direction, maintaining sound image distance.
[0046]
As described above, according to the present invention, as described above, the number of sound
source signals increases, and complex control is performed to change the position for each sound
source with time. Also, the transmission capacity of the auxiliary information can be reduced.
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[0047]
Brief description of the drawings
[0048]
1 is a block diagram showing a first embodiment of the present invention.
[0049]
2 is an explanatory view for explaining the discrimination limit regarding the sense of distance.
[0050]
3 is a diagram showing the relationship between the level difference signal and the presentation
distance.
[0051]
4 is a diagram showing the relationship between the level difference signal and the area number.
[0052]
5 is a block diagram showing a second embodiment of the present invention.
[0053]
6 is an explanatory diagram for explaining the discrimination limit regarding the sense of
direction.
[0054]
7 is an explanatory view for explaining the horizontal direction control method of the sound
image.
[0055]
8 is an explanatory view for explaining the sense of distance control method of the sound image
[0056]
Explanation of sign
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[0057]
DESCRIPTION OF SYMBOLS 1 sound source encoder 2 sound source decoder 3 transmission side
distance control unit 4 reception side distance control unit 5 drive control unit 101, 509 variable
distributor 301 distance to level difference converter 302 level difference to area number
converter 303, 402 Level difference / distance feeling area number table 401 Region number /
level difference converter 403, 5073 Level difference holder 506 Transmission side direction
control unit 507 Reception side direction control unit 811, 812 Delay unit 821 Addition unit 831
Amplification unit 841 Speaker array 5061 Direction to level difference converter 5062 Level
difference to area number converter 5063 Level difference to direction sense area number table
5071 Area number to level difference converter 5072 Level difference to direction sense area
number table
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