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JP2010041425

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DESCRIPTION JP2010041425
To realize a natural sense of localization according to the posture of a listener. A sound emitting
body (14) is mounted on a head of a listener and reproduces a reproduced sound according to an
acoustic signal (SOUT). The sound image localization unit 42 processes the sound signal S0 so
that the sound image of the reproduced sound is localized at the virtual sounding point. The
detector 61 detects the direction DH of the head of the listener. The detector 62 detects the
direction DB of the torso of the listener. The position control unit 22 controls the position of the
virtual sounding point according to the azimuth DH and the azimuth DB so as to be a
predetermined position with respect to the azimuth DB regardless of the change in the azimuth
DH. For example, the position control unit 22 moves the virtual sounding point in the direction
opposite to the change in the direction DH, and moves the virtual sounding point in the direction
of the change in the direction DB. [Selected figure] Figure 2
Sound reproduction apparatus and program
[0001]
The present invention relates to a technique for localizing a sound image of reproduced sound
according to an acoustic signal.
[0002]
A technique for controlling the position where the sound image of reproduced sound is localized
has been conventionally proposed.
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1
For example, in Patent Document 1 and Patent Document 2, the position of the sound image
perceived by the listener is controlled by controlling the position of the sound image according to
the direction of the headphone detected by the sensor (the direction of the head of the listener).
There is disclosed a technique of fixing regardless of the direction of. Patent Document 1:
Japanese Patent Application Laid-Open No. 4-44500 Patent No. 3624805
[0003]
In the techniques of Patent Document 1 and Patent Document 2, only the direction of the head of
the listener is reflected in the position of the sound image, so even if the direction of the torso of
the listener changes, the sound image is localized Position (the position relative to the space
where the listener is present) does not change. Therefore, the listener of the reproduced sound
may feel discomfort as exemplified below.
[0004]
Now, it is assumed that the listener views a picture (for example, a movie) using a portable
display device. In the techniques of Patent Document 1 and Patent Document 2, since the
orientation of the head of the listener is reflected in the position of the sound image, the listener
is stationary with the display device (that is, the orientation of the torso does not change). When
the direction is changed, the sound image is localized at an appropriate position with respect to
the image of the display device possessed by the listener. However, since only the direction of the
head of the listener is reflected in the position of the sound image in the techniques of Patent
Document 1 and Patent Document 2, if the direction of the listener changes with the display
device (for example, the display device is installed When the direction of the vehicle changes),
the image of the display device and the position of the sound image do not match. Therefore, the
listener of the reproduced sound may feel uncomfortable. With the background described above,
it is an object of the present invention to realize a natural sense of localization in accordance with
the posture of a listener.
[0005]
In order to solve the above problems, the sound reproducing apparatus according to the present
invention is a sound emitting device mounted on the head of a listener and reproducing a
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reproduction sound according to the sound signal, and a sound generation point of the
reproduction sound being a virtual sounding point Sound image localization means for
processing an acoustic signal so as to be localized, a first detection body for detecting a first
direction of the head of the listener, and a second detection body for detecting a second direction
of the trunk of the listener; And position control means for controlling the position of the virtual
sounding point in accordance with the first direction and the second direction so as to be at a
predetermined position with respect to the second direction regardless of the change in the first
direction. For example, the position control means moves the virtual sounding point in the
direction opposite to the change in the first direction, and moves the virtual sounding point in the
direction of the change in the second direction. In the above configuration, the position of the
virtual sounding point is controlled to be a predetermined position with respect to the second
orientation regardless of the change in the first orientation, so a natural sense of localization
(according to the orientation of the listener For example, it is possible to cause the listener to
perceive the presence as if the user is moving with the acoustic space in which the virtual
sounding point is installed.
[0006]
In a preferred aspect of the present invention, in the first mode, the position control means is
adapted to be in a predetermined position with respect to the second orientation regardless of a
change in the first orientation according to the first orientation and the second orientation. The
position of the virtual sounding point is controlled according to the first direction so that the
position of the virtual sounding point is controlled and in the second mode the predetermined
position does not depend on the second direction regardless of the change of the first direction.
Control. In the above aspect, whether or not to reflect the orientation of the torso of the listener
on the position of the virtual sounding point is switched, so that it is possible to make the listener
perceive a sound image appropriate for the state of the listener .
[0007]
In a preferred embodiment of the present invention, the first detection body detects a rotation
angle about each of three mutually orthogonal axes as a first orientation, and the second
detection body has each of three mutually orthogonal axes. Is detected as a second direction. In
the above aspect, since the rotation angles around each of three mutually orthogonal axes are
detected as the first orientation or the second orientation, for example, in addition to the
operation of rotating the head in the horizontal plane, It is possible to reflect the motion of tilting
the head to the position of the virtual sounding point.
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[0008]
In a preferred aspect of the present invention, storage means for storing transfer characteristics
from a sound generation point to a sound collection point for each of a plurality of sound
generation points, and transfer characteristics at virtual sound generation points set by position
control means are stored in the storage means. The sound image localization means adds the
transfer characteristic after interpolation by the interpolation means to the sound signal. In the
above aspect, since the transfer characteristics at the virtual sounding point are calculated by
interpolation of two or more transfer characteristics, there is an advantage that the data amount
of the transfer characteristics to be stored in the storage means can be reduced. In a further
preferred aspect, the interpolation means is a delay specifying means for specifying a delay in
each of two or more transfer characteristics used for interpolation, and a characteristic for
interpolating two or more transfer characteristics with the delay specified by the delay specifying
means removed. Interpolation means, delay interpolation means for interpolating each delay of
two or more transfer characteristics, and delay after interpolation by the delay interpolation
means is added to the transfer characteristics after interpolation by the characteristic
interpolation means And delay adding means for calculating transfer characteristics. In the above
aspect, since the delay extracted from each transfer characteristic is added after interpolation of
the transfer characteristic, it is possible to calculate the transfer characteristic accurately
reflected to the feature related to the delay of the transfer characteristic prepared in advance. It
is possible.
[0009]
The second detection body is fixed to, for example, a portable housing that accommodates the
sound image localization means and the position control means. In a further preferred
embodiment, the second detection body is fixed to a strap for suspending the housing of the
sound reproduction device on the body of the listener. According to the aspect in which the
second detection body is fixed to the strap, there is an advantage that the orientation of the torso
of the listener can be accurately detected while miniaturizing the housing of the sound
reproduction device.
[0010]
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The sound reproducing apparatus according to another aspect of the present invention is a
sound reproducing apparatus that generates a reproduction sound according to the sound signal
on a sound emitting body mounted on the head of a listener, and the sound image of the
reproduction sound is a virtual sounding Sound image localization means for processing an
acoustic signal so as to be localized at a point, and the first orientation so as to be at a
predetermined position with respect to the second orientation of the listener's torso regardless of
the first orientation of the listener's head And position control means for controlling the position
of the virtual sounding point according to the second direction. In the above aspect, since the
position of the virtual sounding point is controlled to be a predetermined position with respect to
the second orientation regardless of the change in the first orientation, a natural localization
feeling according to the orientation of the listener can be obtained. It is possible to make the
listener perceive.
[0011]
In the configuration in which the position of the virtual sounding point is controlled based only
on the rotation of the head in the horizontal plane, there is a problem that the operation of tilting
the head back and forth or to the left and right is not reflected in the position of the virtual
sounding point. Therefore, in the sound reproducing apparatus according to another aspect of
the present invention, the sound emitting body mounted on the head of the listener and
reproducing the reproduction sound according to the sound signal and the sound image of the
reproduction sound are localized at the virtual sounding point Sound image localization means
for processing an acoustic signal, a first detection body for detecting the first direction of the
head of the listener as a rotation angle about each of three mutually orthogonal axes, and a first
direction of the first direction And position control means for controlling the position of the
virtual sound generation point according to the first direction so as to be at a predetermined
position regardless of the change. In the above configuration, since the first direction is specified
as the rotation angle around each of three orthogonal axes, the listener has a head in comparison
with, for example, a configuration in which only rotation in the horizontal plane is detected.
There is an advantage that the position of the virtual sounding point can be controlled so that the
displacement of the listener's head can be compensated with high accuracy even when the head
is tilted back and forth or left and right.
[0012]
Further, the sound reproducing apparatus according to each of the above aspects is realized by
hardware (electronic circuit) such as DSP (Digital Signal Processor) dedicated to sound
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reproduction, and general purpose such as CPU (Central Processing Unit) It is also realized by the
cooperation of the arithmetic processing unit and the program. A program according to a specific
aspect is a program for causing a sound emitting body mounted on the head of a listener to
generate a reproduced sound according to an acoustic signal, and a sound image of the
reproduced sound is localized at a virtual sounding point According to the first orientation and
the second orientation so as to be at a predetermined position with respect to the second
orientation of the listener's torso regardless of the sound image localization processing for
processing the acoustic signal and the first orientation of the listener's head And causing the
computer to execute position control processing for controlling the position of the virtual
sounding point. According to the program of the present invention, the same operation and effect
as the sound reproduction apparatus according to each of the above aspects can be achieved.
The program of the present invention is provided to the user in the form of being stored in a
computer readable recording medium and installed on the computer, and is also provided from
the server apparatus in the form of distribution via a communication network and installed on
the computer Be done.
[0013]
<A: First Embodiment> FIG. 1 is an external view of a sound reproducing apparatus according to
a first embodiment of the present invention. The sound reproducing apparatus 100 is a portable
device (portable audio player) that reproduces various sounds such as voices and musical tones,
and includes a main unit 12 and a sound emitting body 14. The main unit 12 generates and
outputs two systems of audio signals SOUT (SOUT_R, SOUT_L) in stereo format. The sound
emitting body 14 is a device (headphones or earphones) that emits reproduction sound
according to each sound signal SOUT output from the main unit 12 and is a head of a user
(hereinafter referred to as "listener") who listens to the reproduction sound. It is attached to the
department. The sound emitting body 14 is mounted on the right ear of the listener and emits
the sound emission unit 14R that emits the reproduction sound corresponding to the sound
signal SOUT_R, and the reproduction sound corresponding to the sound signal SOUT_L is
mounted on the left ear of the listener It is comprised with the sound emission part 14L to
radiate. The listener is able to hold the main body 12 to the torso (for example, to store it in a
pocket of clothes) and to move while the sound emitting body 14 is attached to the head.
[0014]
FIG. 2 is a block diagram of the main body 12. As shown in FIG. 2, the main unit 12 is realized by
a computer system including an arithmetic processing unit 20, a storage unit 32, an input unit
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34, a display unit 36, and a signal processing unit 40. The arithmetic processing unit 20, the
storage unit 32, and the signal processing unit 40 are accommodated in a housing 50 (FIG. 1) in
which the input unit 34 and the display unit 36 are arranged. Arithmetic processing unit 20
realizes a plurality of functions (position control unit 22 and characteristic setting unit 24) by
executing a program stored in storage device 32.
[0015]
The storage device 32 stores a program executed by the arithmetic processing unit 20 and data
used by the arithmetic processing unit 20. A known recording medium such as a semiconductor
recording medium or a magnetic recording medium is arbitrarily adopted as the storage device
32. The storage device 32 stores an acoustic signal S0 (sample series) representing an acoustic
waveform for each music, for example. In addition, the storage device 32 stores a plurality of
transfer characteristic data D representing the transfer characteristic (head-related transfer
function) given to the sound signal S0.
[0016]
The signal processing device 40 is an electronic circuit (DSP) that processes the acoustic signal
S0 to generate an acoustic signal SOUT (SOUT_R, SOUT_L). As shown in FIG. 2, the signal
processing device 40 includes a sound image localization unit 42 and a D / A conversion unit 44.
The sound image localization unit 42 is a sound image for localizing the sound image perceived
by the listener when listening to the reproduced sound from the sound emitting body 14 at a
virtual sounding point at a specific position (hereinafter referred to as “virtual sounding
point”). An acoustic signal Q (Q_R, Q_L) is generated by executing localization processing on the
acoustic signal S0. The D / A conversion unit 44 converts the digital sound signal Q (Q_R, Q_L)
generated by the sound image localization unit 42 into an analog sound signal SOUT (SOUT_R,
SOUT_L) and outputs the sound signal to the sound emitting body 14.
[0017]
FIG. 3 is a block diagram of the sound image localization unit 42. As shown in FIG. As shown in
FIG. 3, the sound image localization unit 42 is configured to include a signal separation unit 72, a
convolution calculation unit 74, and a signal combination unit 76. The signal separation unit
(surround codec) 72 generates sound signals S (Sd_L, Sd_R, Sd_C, Sd_LS, Sd_RS, SLF) of a
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plurality of systems (5.1 ch) from the sound signal S0 stored in the storage device 32. Each of the
five systems of acoustic signals Sd (Sd_L, Sd_R, Sd_C, Sd_LS, Sd_RS) other than the acoustic
signal SLF is an acoustic signal coming from a specific direction (hereinafter referred to as a
"sound receiving direction") to the listener. Equivalent to. More specifically, the sound signal Sd_L
and the sound signal Sd_R correspond to sounds coming from the front left and right with
respect to the listener. The sound signal Sd_C corresponds to the sound coming from the front of
the listener, and the sound signal Sd_LS and the sound signal Sd_RS correspond to the sounds
coming from the left and right behind the listener. On the other hand, the acoustic signal SLF
corresponds to the sound in the low frequency range.
[0018]
The convolution calculation unit 74 adds a transfer characteristic (head transfer function) H to
each acoustic signal Sd processed by the signal separation unit 72. As shown in FIG. 3, the
convolution calculation unit 74 includes five filter processing units 78 to which each acoustic
signal Sd (Sd_L, Sd_R, Sd_C, Sd_LS, Sd_RS) other than the acoustic signal SLF is supplied. Each
filter processing unit 78 includes a filter 78R for the right ear and a filter 78L for the left ear.
Each of the filter 78L and the filter 78R is a FIR (Finite Impulse Response) filter that performs a
convolution operation of the transfer characteristic H on the acoustic signal Sd supplied from the
signal separation unit 72. The transfer characteristic H is, for example, a coefficient sequence
representing a waveform on the time axis of an impulse response, and an arithmetic processing
unit for the filter 78R and the filter 78L of each filter processing unit 78 so that the sound image
of the reproduced sound is localized at a virtual sounding point. 20 (characteristic setting unit
24) individually set. The setting of the transfer characteristic H will be described later.
[0019]
The signal synthesis unit 76 adds the acoustic signal Sd (Sd_L, Sd_R, Sd_C, Sd_LS, Sd_RS)
processed by the filter 78L of each filter processing unit 78 and the acoustic signal SLF
generated by the signal separation unit 72 to an acoustic signal. Generate signal Q_L. Similarly,
the signal combining unit 76 generates an acoustic signal Q_R by adding the acoustic signal Sd
(Sd_L, Sd_R, Sd_C, Sd_LS, Sd_RS) and the acoustic signal SLF after being processed by the filter
78R of each filter processing unit 78. Do. The acoustic signal Q_L and the acoustic signal Q_R
generated by the signal combining unit 76 are converted into the acoustic signal SOUT_L and the
acoustic signal SOUT_R by the D / A conversion unit 44 and then output to the sound emitting
body 14.
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[0020]
The input device 34 of FIG. 2 is composed of operators operated by the user for instructing the
sound reproduction apparatus 100. For example, the user appropriately operates the input
device 34 to select a music (sound signal S0) to be reproduced by the sound reproduction
apparatus 100 or specify an initial position of a virtual sounding point. The display device 36
displays, for example, names of a plurality of music pieces that are candidates for selection by
the user, an image representing the relationship between a listener and a virtual sounding point,
or a moving image such as a movie or animation.
[0021]
As shown in FIG. 2, the sound reproducing apparatus 100 includes a detection body 61 and a
detection body 62. Each of the detection body 61 and the detection body 62 is a sensor that
detects its own orientation. For example, the detection body 61 and the detection body 62 are
configured by appropriately combining a gyro sensor, a geomagnetic sensor, and an acceleration
sensor. As shown in FIG. 1, the detection body 61 is mounted on a sound emitting body 14
(sound emitting portion 14R or sound emitting portion 14L) that moves with the head of the
listener to detect the direction DH of the head of the listener . The detection body 62 is housed,
for example, in the housing 50 of the main body 12 moving with the torso of the listener, and
detects an orientation DB of the torso (a portion other than the head) of the listener.
[0022]
Changes in the azimuth DH and the azimuth DB are detected as Euler angles based on each of
three mutually orthogonal axes (XYZ coordinate system) as shown in FIG. In FIG. 4, the X-axis
corresponds to the front-rear direction of the listener (the positive side is the front), the Y-axis
corresponds to the left-right direction, and the Z-axis corresponds to the top-bottom direction.
The rotation angles [αh, βh, γh] of the head direction DH are the rotation angle αh (rotation
angle of the head in the horizontal plane) around the Z axis and the rotation angle βh (midline)
around the Y axis It is defined by the rotation angle of the head in the plane) and the rotation
angle γh (rotation angle of the head in the frontal plane) about the X axis. The rotation angle
βh corresponds to an angle for tilting the head back and forth (back and forth bending), and the
rotation angle γh corresponds to an angle for tilting the head left and right while facing the
front (left and right side bending). As in the case of the direction DH, the rotation angles [αb,
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βb, γb] of the direction DB of the body are the rotation angle αb around the Z axis, the rotation
angle βb around the Y axis, and the X axis It is defined by the rotation angle γb.
[0023]
The position control unit 22 shown in FIG. 2 variably controls the position of the virtual sounding
point according to both the direction DH detected by the detector 61 and the direction DB
detected by the detector 62. More specifically, even if the direction DH of the listener's head
changes, the position control unit 22 does not change the position of the virtual sounding point
with respect to the direction DB of the body, and according to the direction DB of the body The
position of the virtual sounding point is controlled according to both the direction DH and the
direction DB so that the position of the virtual sounding point changes. More specifically, the
position control unit 22 moves the virtual sounding point in the direction opposite to the change
in the heading DH of the head and moves the virtual sounding point in the direction of the
change in the heading DB of the trunk.
[0024]
Now, it is assumed that the head direction DH is rotated by an angle [αh, βh, γh]. Since the
sound emitting body 14 is fixed to the head of the listener, assuming that the virtual sounding
point is not moved according to the head direction DH, the position of the sound image perceived
by the listener is expressed by equation (1) Move from the initial position [x, y, z] to the position
[x ', y', z '] rotated by the angle [αh, βh, γh] in conjunction with the rotation of the head
direction DH. Do. The matrix M0 in equation (1) means rotation of the angles [αh, βh, γh].
[0025]
Even when the heading DH of the head rotates, in order not to change the position of the virtual
sounding point with respect to the heading DB of the trunk, the position control unit 22
generates virtual sound by the same angle (absolute value) in the opposite direction to the
rotation of the heading DH. Rotate points. That is, as expressed by the following equation (2), the
virtual position [x1, y1, z1] is a virtual position [x1, y1, z1] rotated from the initial position [x, y,
z] by an angle [-αh, -βh, -γh]. Move the pronunciation point. In addition, the matrix M1 of
Formula (2) means rotation of angle [-(alpha) h,-(beta) h,-(gamma) h].
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[0026]
Furthermore, in order to move the virtual sounding point according to the heading DB of the
trunk, the position control unit 22 moves the virtual sounding point by the same angle in the
direction of rotation of the heading DB. That is, as expressed by the following equation (3), the
virtual sounding point is located at the position [x2, y2, z2] rotated by the angle [αb, βb, γb]
from the initial position [x, y, z] Move it. The matrix M2 of Equation (3) means rotation of the
angles [αb, βb, γb].
[0027]
FIG. 5 is a flowchart of the operation of the position control unit 22. The position control unit 22
sequentially updates the positions [x, y, z] of the virtual sounding points stored in the storage
device 32 by repeating the process of FIG. 5 at a predetermined cycle, for example. The initial
value of the position [x, y, z] of the virtual sounding point is set, for example, according to the
operation on the input device 34.
[0028]
When the process of FIG. 5 is started, the position control unit 22 determines whether or not the
direction DH of the head of the listener has changed (step S1). When the direction DH changes,
the position control unit 22 executes the calculation of Equation (2) for the rotation angle [αh,
βh, γh] of the direction DH and the current position [x, y, z]. The position [x1, y1, z1] of the
virtual sounding point after movement is calculated (step S2), and the position [x, y, z] stored in
the storage device 32 is updated to the position [x1, y1, z1] (Step S3). If the heading DH has not
changed, the processing in step S2 and step S3 (update of the position [x, y, z]) is not performed.
[0029]
Next, the position control unit 22 determines whether or not the orientation DB of the torso of
the listener has changed (step S4). When the orientation DB changes, the position control unit 22
executes the operation of Equation (3) for the rotation angle [αb, βb, γb] of the orientation DB
and the current position [x, y, z]. The position [x2, y2, z2] of the virtual sounding point after
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movement is calculated (step S5), and the position [x, y, z] stored in the storage device 32 is
updated to the position [x2, y2, z2] (Step S6). If the orientation DB has not changed, the
processing in step S5 and step S6 (update of the position [x, y, z]) is not performed.
[0030]
Furthermore, the position control unit 22 is configured to store the position [x, y, z] stored in the
storage device 32 at the current stage (ie, the position [x, y, z] after updating in the immediately
preceding step S3 or step S6. Is converted into the direction [θ, φ] defined by the horizontal
angle θ and the elevation angle φ (step S7). As shown in FIG. 6, for the horizontal angle θ, for
example, a straight line Lxy passing through the coordinate Pxy obtained by projecting the
position [x, y, z] of the virtual sounding point on the XY plane (horizontal plane) of the XYZ
coordinate system The elevation angle φ corresponds to the angle formed by the straight line L
passing through the position [x, y, z] of the virtual sounding point and the origin with the straight
line Lxy. The direction [θ, φ] after conversion by the position control unit 22 is stored in the
storage device 32 together with the position [x, y, z] before conversion.
[0031]
The storage device 32 stores transfer characteristic data D in advance for each of the plurality of
directions [θ, φ]. That is, as shown in FIG. 7, the transfer characteristic data D is stored in the
storage device 32 for each combination of a plurality of horizontal angles θ (θ1, θ2, ...) and a
plurality of elevation angles φ (φ1, φ2, ...). Be done. The transfer characteristic data D includes
a plurality of transfer characteristics H (H_L, H_R, H_C) generated for each sound receiving
direction corresponding to the respective acoustic signals Sd (Sd_L, Sd_R, S_C, Sd_LS, Sd_RS)
generated by the signal separation unit 72. , H_LS, H_RS). Of the transfer characteristic data D
stored in the storage device 32 for the direction [θ, φ], the transfer characteristic H
corresponding to a specific acoustic signal Sd (sound receiving direction) is, for example, the
origin (sound collecting point) of the XYZ coordinate system. It is a coefficient sequence
representing the waveform of an impulse response that arrives at the origin from the sound
reception direction when the impulse sound is generated at the sound generation point in the
direction [θ, φ] as seen from the above. Each transfer characteristic H is divided into a transfer
characteristic hR representing a waveform of an impulse response perceived by the right ear of
the listener and a transfer characteristic hL representing a waveform of an impulse response
perceived by the left ear of the listener.
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[0032]
Characteristic setting unit 24 in FIG. 2 specifies transfer characteristic data D corresponding to
the direction [θ, φ] of the virtual sounding point set by position control unit 22 and instructs
sound image localization unit 42 (convolution calculation unit 74). Do. The transfer characteristic
H corresponding to one sound receiving direction among the transfer characteristic data D
specified by the characteristic setting unit 24 is supplied and set to the filter processing unit 78
corresponding to the sound receiving direction in the convolution calculation unit 74. . For
example, in the filter processing unit 78 to which the acoustic signal Sd_L is supplied, the
transfer characteristic H_L included in the transfer characteristic data D specified by the
characteristic setting unit 24 is set. More specifically, of the transmission characteristics H, the
transmission characteristic hR for the right ear is set to the filter 78R, and the transmission
characteristic hL for the left ear is set to the filter 78L. As described above, the transfer
characteristic data D corresponding to the direction [θ, φ] of the virtual sounding point is used
for the calculation by the convolution calculation unit 74 (addition of the transfer characteristic
H to the acoustic signal Sd). The sound image perceived by the listener of the reproduction sound
from is localized at the virtual sounding point set by the position control unit 22.
[0033]
When the transfer characteristic data D of the horizontal angle θ and the elevation angle φ
corresponding to the direction [θ, φ] set by the position control unit 22 exists in the storage
device 32, the characteristic setting unit 24 stores the transfer characteristic data D. The sound
image localization unit 42 is instructed to obtain it from the device 32. However, since the
horizontal angle θ and the elevation angle φ of each transfer characteristic data D stored in the
storage device 32 are discrete, the transfer characteristic data D of the direction [θ, φ] of the
virtual sounding point set by the position control unit 22 May not be prepared in the storage
device 32. Therefore, the characteristic setting unit 24 of the present embodiment includes the
interpolation unit 80. When the transfer characteristic data D in the direction [θ, φ] set by the
position control unit 22 does not exist in the storage device 32, the interpolation unit 80 stores
the transfer characteristic data D corresponding to the direction [θ, φ] A plurality of transfer
characteristic data D stored in 32 are generated by interpolation. In the following, it is assumed
that m transfer characteristic data D are used for interpolation by the interpolation unit 80 (m is
a natural number).
[0034]
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FIG. 8 is a block diagram of the interpolation unit 80. As shown in FIG. As shown in FIG. 7, the
interpolation unit 80 includes an up-sampling unit 81, a delay specifying unit 82, a delay
removing unit 83, a delay interpolation unit 84, a characteristic interpolation unit 85, a delay
adding unit 86, and a down-sampling unit 87. Configured The interpolation of the transfer
characteristic H by the interpolation unit 80 is individually executed for each of the transfer
characteristics H used for the calculation by the convolution calculation unit 74. That is, the
operation of interpolating the transfer characteristic hR for the right ear and the transfer
characteristic hL for the left ear for each of a plurality of sound receiving directions (five
directions) corresponding to the respective sound signals Sd is repeated in the same procedure.
However, in the following, from the viewpoint of preventing the explanation from being
complicated, in each of the m transmission characteristic data D, the transmission characteristic
H (m transmission characteristics H (H 1 to H Only the configuration and procedure for
interpolating one transfer characteristic HNEW from Hm) will be representatively described.
[0035]
The upsampling unit 81 of FIG. 8 raises the sampling frequency of each of the m transfer
characteristics H (H1 to Hm) to N times in the upsampling process (N> 1). The delay specifying
unit 82 specifies the delay amount dA (dA1 to dAm) for each of the m transfer characteristics H
(H1 to Hm) processed by the upsampling unit 81. As shown in FIG. 8, in the delay amount dAi (i =
1 to m), the impulse response is actually collected from the time when the impulse sound is
generated at the time of measurement of the transmission characteristic Hi (the origin on the
time axis of the transmission characteristic Hi). It is the length of time until it starts being
sounded. The delay removing unit 83 generates the transfer characteristic HAi by removing the
delay amount dAi of the transfer characteristic Hi from each of the m transfer characteristics H
(H1 to Hm). More specifically, the delay removing unit 83 generates the transfer characteristic
HAi by moving the transfer characteristic Hi on the time axis by the delay amount dAi (advancing
the phase of the transfer characteristic Hi).
[0036]
The delay interpolation unit 84 calculates the delay amount d by interpolating the delay amounts
dA (dA1 to dAm) of the m transfer characteristics H (H1 to Hm). For example, the delay
interpolation unit 84 calculates a weighted sum of m delay amounts dA1 to dAm as a delay
amount d after interpolation. On the other hand, the characteristic interpolation unit 85 specifies
the transfer characteristic H0 by interpolating the m transfer characteristics HA1 to HAm
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calculated by the delay removing unit 83. A known technique is arbitrarily adopted for
interpolation of m transfer characteristics HA1 to HAm. For example, the characteristic
interpolation unit 85 calculates the weighted sum of m transfer characteristics HA1 to HAm as
the post-interpolation transfer characteristic H0.
[0037]
The delay adding unit 86 calculates the transfer characteristic HNEW by adding the delay
amount d after interpolation by the delay interpolation unit 84 to the transfer characteristic H0
after interpolation by the characteristic interpolation unit 85. The addition of the delay amount d
is processing for delaying the transfer characteristic H0 by the delay amount d on the time axis
(delaying the phase of the transfer characteristic H0). The downsampling unit 87 reduces the
sampling frequency of the transfer characteristic HNEW generated by the delay adding unit 86
to 1 / N times in the downsampling process. The transfer characteristic HNEW generated in the
above-described procedure is set as the transfer characteristic H in each filter of the convolution
calculation unit 74.
[0038]
Next, a specific example of the process performed by the interpolation unit 80 will be described.
Assuming that the horizontal angle θ of the direction [θ, φ] of the virtual sounding point set by
the position control unit 22 is 13 ° and the elevation angle φ is 5 ° ([θ, φ] = [13, 5]) in the
following Do. Assuming that the resolution (step size) of each of the horizontal angle θ and the
elevation angle φ for which the transfer characteristic data D is prepared is 10 °, as shown in
FIG. 9, the horizontal angle sandwiching the target horizontal angle (13 °) Four (m = 4) transfer
characteristic data D ([θ, φ] =) corresponding to θ (θ = 10, 20) and an elevation angle φ (φ =
0, 10) sandwiching the target elevation angle (5 °) The transfer characteristics H1 to H4 of each
of [10,0], [20,0], [10,10], and [20,10] are used for generation of the transfer characteristic HNEW
by the interpolation unit 80.
[0039]
More specifically, the transfer characteristic H1 ([10,0]) and the transfer characteristic H2
([20,0]) are used to calculate the transfer characteristic H12 (the transfer characteristic H
corresponding to [13,0]), The transmission characteristic H3 ([10, 10]) and the transmission
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characteristic H4 ([20, 10]) are used to calculate the transmission characteristic H34 (the
transmission characteristic H corresponding to [13, 10]). Then, the target transmission
characteristic HNEW (the transmission characteristic H corresponding to [13, 5]) is generated by
interpolation between the transmission characteristic H12 and the transmission characteristic
H34. Further details are as follows.
[0040]
Each of the transfer characteristics H1 to H4 processed by the upsampling unit 81 is separated
into a transfer characteristic HAi and a delay amount dAi by the delay specifying unit 82 and the
delay removing unit 83. The characteristic interpolation unit 85 calculates the transfer
characteristic H12 by interpolation between the transfer characteristic HA1 and the transfer
characteristic HA2, and calculates the transfer characteristic H34 by interpolation between the
transfer characteristic HA3 and the transfer characteristic HA4. For the calculation
(interpolation) of the transfer characteristic H12 and the transfer characteristic H34, for
example, the following formula (1a) and formula (1b) are used. H12 = 0.8 · HA1 + 0.2 · HA2 (1a)
H34 = 0.8 · HA3 + 0.2 · HA4 ... (1b) Furthermore, the delay interpolation unit 84 is expressed, for
example, by the following equation (2a) and equation (2b) Thus, the delay amount d12 is
calculated by interpolation between the delay amount dA1 and the delay amount dA2, and the
delay amount d34 is calculated by interpolation between the delay amount dA3 and the delay
amount dA4. d12 = 0.8dA1 + 0.2dA2 (2a) d34 = 0.8dA3 + 0.2dA4 (2b) As understood from the
above equations, the characteristic interpolation unit 85 and the delay interpolation unit 84 The
weighting values applied to the calculation are selected to be numerical values larger as the
weighting values for the horizontal angle θ close to the target horizontal angle θ and the
elevation angle φ and the transfer characteristic HAi of the elevation angle φ and the delay
amount dAi.
[0041]
Next, the delay interpolation unit 84 calculates the transfer characteristic H0 by interpolation
between the transfer characteristic H12 and the transfer characteristic H34 (for example,
equation (3a)), and the delay interpolation unit 84 calculates the delay amount d12 by the
interpolation between the delay amount d34. The delay amount d is calculated (for example,
formula (3b)). H0 = 0.5 · H12 + 0.5 · H34 (3a) d = 0.5 · d12 + 0.5 · d34 (3b)
[0042]
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Then, the delay adding unit 86 calculates the target transfer characteristic HNEW by adding the
delay amount d of the equation (3b) to the transfer characteristic H0 calculated by the equation
(3a). Further, the transfer characteristic HNEW subjected to the processing by the downsampling
unit 87 is set as the transfer characteristic H in each filter of the convolution calculation unit 74.
The above is the operation of the characteristic setting unit 24.
[0043]
As described above, in the present embodiment, even when the direction DH of the head of the
listener changes, the position of the virtual sounding point with respect to the direction DB of the
body does not change, and The position of the virtual sounding point is controlled according to
both the direction DH and the direction DB so that the position of the virtual sounding point
changes accordingly. For example, assuming that the sound image is localized forward while the
listener is traveling in the east direction, even if the listener rotates the head during the east
direction, the virtual sounding point The position of is maintained in front (east side) of the
listener. On the other hand, when the progress of the listener changes from the east direction to
the south direction, the position of the virtual sounding point also changes from the east side to
the south side of the listener (maintained ahead of the listener). Therefore, it is possible to cause
the listener to perceive a sense of localization as if moving along with the acoustic space in which
the virtual sounding point is installed (a feeling of realism as if the torso were moving with the
speaker fixed to the body) is there.
[0044]
For example, assuming that the listener carries the sound reproducing apparatus 100 while
displaying a moving image such as a movie on the display device 36, the listener may of course
listen to the sound reproducing apparatus 100, even when the listener is stationary. It is possible
to maintain the alignment between the image displayed on the display device 36 and the position
of the virtual sounding point even when moving along with the change of direction.
[0045]
Furthermore, in the present embodiment, rotation angles (αh, βh, γh) about each of three axes
(Z axis, Y axis, X axis) orthogonal to each other are detected as the direction DH of the head of
the listener. Ru.
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Therefore, for example, compared with the case of detecting only the rotation of the head in the
horizontal plane (the action of shaking the head to the left and right), the listener may hear the
head even if the head tilts back and forth or to the left and right. There is an advantage that the
change of the position of the perceived virtual sounding point of is compensated (maintained at
the position of the predetermined relationship with respect to the orientation DB of the trunk).
[0046]
Further, since the transfer characteristic H corresponding to the combination of the horizontal
angle θ and the elevation angle φ for which the transfer characteristic data D is not prepared is
calculated by interpolation of a plurality of transfer characteristics H in the storage device 32,
storage in the storage device 32 There is also an advantage that the capacity of the transfer
characteristic data D that needs to be reduced can be reduced. Further, the delay amount d
obtained by interpolating the delay amounts dA1 to dAm extracted from the m transfer
characteristics H1 to Hm used for interpolation is added to the post-interpolation transfer
characteristics H0 of the transfer characteristics HA1 to HAm There is also an advantage that the
transfer characteristic H corresponding to the desired horizontal angle θ and elevation angle φ
can be generated with high accuracy.
[0047]
Second Embodiment Next, a second embodiment of the present invention will be described. In
addition, about the element in which an effect | action or a function is equivalent to 1st
Embodiment in each form illustrated below, the code | symbol same as the above is attached |
subjected, and detailed description of each is abbreviate | omitted suitably.
[0048]
The sound reproducing apparatus 100 of the present embodiment has two types of operation
modes (a first mode and a second mode). In the first mode, as in the first embodiment, the
operation mode for controlling the virtual sounding point at a predetermined position with
respect to the orientation DB of the trunk regardless of the change in the orientation DH of the
listener's head (ie, virtual sounding The mode in which the position of the point is determined
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relative to the position of the listener's torso). The second mode is an operation mode in which
the virtual sounding point is controlled to a predetermined position independent of the
orientation DB of the trunk, regardless of the change in the orientation DH of the listener's head.
That is, in the second mode, the virtual sounding point is set at a position based on the space
where the listener is located (absolute position in the sense that it does not depend on the
direction DB of the trunk). The listener operates the input device 34 to select one of the first
mode and the second mode.
[0049]
FIG. 10 is a flowchart of the operation of the position control unit 22 in this embodiment. As
shown in FIG. 10, the position control unit 22 executes step S9 immediately after step S3
(immediately before step S4) in the first embodiment (FIG. 5). In step S9, the position control unit
22 determines whether the first mode is selected as the operation mode of the sound
reproducing apparatus 100.
[0050]
When the first mode is selected, the position control unit 22 updates the position [x, y, z] stored
in the storage device 32 according to the change in the orientation DB of the trunk, as in the first
embodiment. To perform the process (steps S4 to S6). On the other hand, when the second mode
is selected, the position control unit 22 executes step S7 without executing the processing from
step S4 to step S6. Therefore, in the second mode, the change in the heading DB of the trunk is
not reflected in the position of the virtual sounding point.
[0051]
As described above, in the present embodiment, since the orientation DB of the torso of the
listener is selectively reflected on the position of the virtual sounding point according to the
operation mode, for example, the listener hears an appropriate sound image according to the
listener's state It is possible to make For example, in the first mode in which the virtual sounding
point is set at a predetermined position based on the orientation DB of the torso of the listener,
whether the listener is moving together with the virtual acoustic space in the moving state The
listener perceives such natural sense of presence. However, when, for example, the listener falls
down in the first mode, the virtual sound space may also be perceived as if it overturns with the
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body of the listener, and the listener may feel discomfort.
[0052]
In the second mode of the present embodiment, since the orientation DB of the torso of the
listener is not reflected in the position of the virtual sounding point, the virtual sound space
perceived by the listener is independent of the posture of the torso of the listener (e.g. Even if the
listener falls over, it is maintained at a position relative to the space where the listener is located.
Therefore, compared with the case where the second mode can not be selected, it is possible to
make the listener perceive a natural sense of localization regardless of the posture of the listener.
As understood from the above description, the first mode is preferable when the listener views
the sound while moving, and the second mode when the listener looks at the sound while
standing still in the room, for example. Is preferred.
[0053]
<C: Third Embodiment> FIG. 11 is an external view of a sound reproducing apparatus 100
according to a third embodiment of the present invention. As shown in FIG. 11, the sound
reproducing apparatus 100 includes a strap 52 for suspending the main body 12 (the housing
50) on the listener's body (for example, a neck strap for suspending the main body 12 on the
neck of the listener). ). The strap 52 is a curvilinear member extending between a portion in the
middle of the cord 54R connecting the sound emitting body 14R to the main body portion 12
and a portion in the middle of the cord 54L connecting the sound emitting body 14L to the main
body portion 12.
[0054]
As shown in FIG. 11, the detection body 62 is mounted on the strap 52. Since the strap 52 is
displaced together with the torso of the listener in a state of being worn on the body of the
listener, the detection body 62 detects the orientation DB of the torso of the listener as in the
first embodiment. The configuration in which the detection body 61 is installed in the sound
emitting body 14 (for example, the sound emitting unit 14R) is the same as that in the first
embodiment.
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[0055]
In the first embodiment in which the detection body 62 is installed in the housing 50, for
example, when the main body 12 is accommodated in the bag held by the listener (that is, when
the main body 12 is displaced with the arm of the listener), There is a possibility that the
orientation DB of the torso of the listener may not be accurately detected. Since the detection
body 62 of the present embodiment is installed on the strap 52 attached to the body of the
listener, the detection body 62 is accurately displaced in conjunction with the trunk of the
listener. Therefore, the orientation DB of the torso of the listener can be accurately detected as
compared with the first embodiment. Further, by installing the detection body 62 on the strap
52, there is also an advantage that the case 50 is miniaturized as compared with the first
embodiment in which the detection body 62 is installed in the case 50.
[0056]
<D: Modified Example> Various modifications are added to each of the embodiments exemplified
above. It will be as follows if the aspect of a specific deformation is illustrated. In addition, two or
more modes may be arbitrarily selected and combined from the following exemplifications.
[0057]
(1) Modification 1 The position at which the detection body 61 or the detection body 62 is
installed is arbitrary. For example, when headphones are adopted as the sound emitting body 14,
the detecting body 61 is installed on the head arm. Moreover, the structure which installed the
detection body 62 in both the housing | casing 50 and the strap 52 is employ | adopted. For
example, the average of the detection value of the detection body 62 of the housing 50 and the
detection value of the detection body 62 of the strap 52 is used for processing of the position
control unit 22 as the orientation DB of the trunk. In addition, the form of the strap 52 is
appropriately changed. For example, a configuration in which an annularly formed strap is fixed
to the housing 50 is also suitable.
[0058]
(2) Modification 2 If the transfer characteristic data D is prepared for the sufficient horizontal
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angle θ and elevation angle φ, or if the accuracy required for the position of the virtual
sounding point is low, the interpolation unit 80 may be omitted. In the configuration in which the
interpolation unit 80 is omitted, only the transfer characteristic data D (transfer characteristic H)
stored in the storage device 32 is used for sound image localization processing of the acoustic
signal S0.
[0059]
(3) Modification 3 The division between the function realized by the arithmetic processing unit
20 and the function realized by the signal processing unit 40 is arbitrarily changed. For example,
a configuration for realizing the sound image localization unit 42 by the arithmetic processing
unit 20 executing a program, and a configuration for realizing the position control unit 22 or the
characteristic setting unit 24 are also adopted.
[0060]
FIG. 1 is an external view of a sound reproduction device according to a first embodiment of the
present invention. It is a block diagram of a sound reproduction apparatus. It is a block diagram
of a sound image localization part. It is a conceptual diagram for demonstrating the angle of a
listener's head and a torso. It is a flowchart of operation | movement of a position control part. It
is a conceptual diagram for demonstrating the format which prescribes | regulates the position of
a virtual sounding point. It is a conceptual diagram of transfer characteristic data. It is a block
diagram of an interpolation part. It is a conceptual diagram for demonstrating the specific
example of operation | movement of an interpolation part. It is a flowchart of operation |
movement of the position control part in 2nd Embodiment of this invention. It is an outline view
of a sound reproduction device concerning a 3rd embodiment of the present invention.
Explanation of sign
[0061]
100: sound reproduction device, 12: main body, 14: sound emitting body, 14R: sound emitting
portion, 14L: sound emitting portion, 20: arithmetic processing unit, 22: position control portion,
24 ... ... characteristic setting unit, 32 ... storage device, 34 ... input device, 36 ... display device, 40
... signal processing device, 42 ... sound image localization unit, 44 ... D / A conversion unit, 50 ...
housing Body 52: Strap 61 61: Detected body 62: Detected body 72: Signal separation unit 74:
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Convoluted operation unit 76: Signal combining unit 78: Filter processing unit 78R: 78 ... filter
78 L ... filter 81 ... up-sampling unit 82 ... delay identification unit 83 ... delay removal unit 84 ...
delay interpolation unit 85 ... characteristic interpolation unit 86 ... delay addition unit 87:
Downsampling unit.
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