JPH03274998

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DESCRIPTION JPH03274998
[0001]
[Industrial field of application] The present invention is a sound field that reproduces a sound
field by reproducing a sound source by simulating a specific indoor sound field and using a
plurality of speakers mainly in audio reproduction and audio reproduction of voice
communication. It relates to the regeneration method. "Prior Art" When playing music by means
of audio reproduction to obtain the atmosphere as if it were in an actual concert hall, or when
listening to the sound of a remote place by communication, it would be as if in a conference room
in an actual remote place. In order to obtain an atmosphere like that, it is necessary to reproduce
those room sound fields in the sound field where the listener is actually present. For that
purpose, the technique which makes the room which a listener is present radiates from the
direction of arrival the signal which is delayed and arrives at a listener by the echo in those
rooms is needed. The means is the multichannel regeneration method. FIG. 6 shows the
configuration of the conventional sound field reproduction method. The sound source signal
from the sound source 1 is supplied to N convolutional operators 2-1 to 2-N, and the outputs of
the operators 2-1 to 2-N are respectively supplied to the speakers 3-1 to 3-N. Ru. The speakers 31 to 3 -N are disposed in the reproduction room 4, and the listener 5 is in the reproduction room
4. The sound source l outputs as a signal a dry source which does not include the reflected sound
of the room sound field to be reproduced among the sounds. The structure of the reflected sound
of the room sound field to be reproduced is allocated to N speakers according to the number N of
the speakers 3-1 to 3-N given to the playback house 4 and the arrangement thereof. Specifically,
the transfer function of the time domain up to the listening point of the room sound field to be
reproduced according to the arrival direction is stored in the convolution unit 2-n (n = 1 + ... N),
and this time domain transfer The listener can reproduce the room to be reproduced by
reproducing the output signal obtained by convolving the function and the output signal of the
sound source l with the corresponding speakers 3-n (n-1,... N). You can experience the sound in
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almost the same way as you do. The output signal of sound source 1 is x (L), and the transfer
function of the time domain to the listening point of the room sound field to be reproduced
according to the arrival direction is h (n, L) (n = 1. ... N, N: number of speakers, t = 0 ..., −−t, 'r:
delay time length sampled)), a signal applied to the speaker 3-n (n = 1 +... N) is represented by
Strictly speaking, it is necessary that the reproduction room 4 itself is an anechoic room with no
reflected sound, and that the speaker 3 be disposed over all the incoming directions of the
reflected sound of the room to be reproduced originally If possible, the effect will be obtained.
[Problems to be Solved by the Invention] In such a method, a common source called dry source
can be used, but the transfer function of the time domain to the listening point of the room sound
field to be reproduced according to the arrival direction is the arrangement of the speakers It has
to be created according to the number and is not realistic.
An object of the present invention is to reproduce a sound field by using a plurality of speakers
to reproduce a sound field. In the sound field reproduction method, the room to be reproduced
by the listener corresponding to the arrangement and the number of speakers of various
reproduction systems. It is about providing the sound field reproduction method which can
experience a sound in the almost same state as being in a house. [Means for Solving the
Problems] According to the present invention, for each time step (sample point) of the transfer
function of the unique sound field, direction information indicating the arrival direction of the
sound is given, and the direction information is used as a reproduction area The value
(magnitude of sound) of each time step of the transfer function is distributed to the speakers to
make a transfer function for each speaker, and reproduced from the corresponding speaker
using the transfer function of each speaker and the signal of the sound source Generate a signal
to be. If the sound source placed in the sound field to be reproduced and the position of the
listener are determined, the sound field is the transfer function from the sound source to the
listener through various paths and each path is from any direction of the listener The transfer
function in the zero time domain, which can be described by the direction information as to
whether the sound arrives, is treated as a sample value system, so h (t) (t = o, ...,? When it is
represented by -1), T values are obtained, each of which can be interpreted as the magnitude of
the sound arriving at time (time step) t. FIG. 1A shows the transfer function h <t> for T = 8 (when
T = 0, h (0) = 0). The arrival direction of the sound arriving at the time (time step) ff f1-1. ... by
dividing into regions labeled with L numbers of L, from 1 to L for the loudness h (t) of each time
(time step) of the transfer function h (L) Direction information I with any value of! , (T) 0 For
example, as shown in FIG. 2, the arrival direction of the sound of the sound field (at the position
of the listener) to be reproduced is (j! =) Labeled with 1.2 and 3.4, the transfer function h (t) of
the sound field is h + (t), h □ (t), bs (t), ha (t) as shown in the four directions. 1) can be expressed
as shown in FIG. 1B. In the case of the transfer function h (L) of FIG. つまりｈ（１）は
ｆｆ１（１）＝１とし、ｈ（２）は１（２）＝２とし、ｈ（３）はｆｆ１（３）＝３とし、
ｈ（４）は１（４）−１とし、ｈ（５）はｌｌ（５）＝２とし、ｈ（６）は１（６）＝４とし、
ｈ（７）はｆｆ１（７）−３とする。 Expressing the sound size h by X bits and the direction
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information 1 by X bits, a transfer function including direction information is represented by a
value h '(L) of x + y bits including the size and direction.
In reality, it may come from two or more directions simultaneously at a certain time (time step) t,
but in this case it is rare, and if it is, the direction information of the largest one of each h (t) is
give. Alternatively, if h (t ± 1) is zero before and after it, give h (t) and 2 (【) by shifting one
sample (time step) back and forth so that multiple directions do not overlap at the same time The
transfer function h ′ (t) including the direction information on the sound field to be reproduced
is described by defining the numbers and the regions of L directions in this manner. The period
of the time step t is equal to the period of twice the frequency of the highest frequency in the
signal, and the number of T is equal to, for example, the reverberation time. An embodiment of
the present invention is shown in FIG. 3, and the parts corresponding to those in FIG. A transfer
function h '(L) including direction information on a sound field to be reproduced in the transfer
function storage circuit 6, for example, functions h (t) and ff1 (t) indicating the first V4A and B
are stored, and the transfer function h (T) is distributed to the speakers whose reproduction area
is the direction according to the direction information X <t> by the direction-specific transfer
function generation circuit 7 to create a transfer function for each speaker 0, for example, a
sound field to be reproduced The number of sound arrival directions and areas in the sound are
divided in a total of eight directions by 45 degrees in the horizontal direction as shown in FIG. 4,
and the sound function at each time step (time) t of the transfer function h (t) Information with
one of eight directions ff1-1 to 8 is provided. On the other hand, the number of channels of the
reproduction system (number of speakers) in the actual reproduction sound field and the
arrangement of the speakers differ depending on the reproduction system, and the specific
arrangement (β) with N channels (speakers) (β) − (1,) ..., given that N) is given to a speaker
whose reproduction region is one or more of direction information, the distribution function for
the direction information in the transfer function h (【) is distributed to the transfer function for
the speaker Create For this reason, for example, from the transfer function h '(t) including the
direction information stored in the transfer function storage circuit 6, the direction information j!
Read (t), create a correspondence table ((α) → (β)) showing which channel (speaker) the value,
(α) = (1, ..., L) corresponds to, The transfer function generation circuit 7 generates directionspecific (speaker-specific) transfer functions for each channel of the reproduction system. This
table is unique to the regeneration system. To execute this method, h '(0), ..., h' (T-1) to h (0), ... h
(τ-1) stored in the transfer function storage circuit 6 1 (0),..., IT-1), and the direction-specific
transfer function generation circuit 7 according to the correspondence table ((α) → (β)) n, k) (n
= 1.
＝４．ｋ＝０． ···· Create T−1), perform convolution with the output signal X (1) of the sound
source 1 in the convolution unit 2-n, and reproduce the result with the speaker 3-n. Figure 5
shows an example of the configuration of the playback system where the listener is present,
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where the number of channels in the playback sound field (the number of speakers) is 4,
speakers are arranged front to back, right to left, and 90 degrees to the front, back, left to right Is
shown. Assuming that the standardized direction information follows the example of FIG. 4, 1 (t)
is 1.2 for n = 1, 3.4 for n = 2, 5.6 for n = 3, 7.8 forms a correspondence table (α 1 → (β)
corresponding to n = 4. The transfer function h (1, k) for the speaker 3-1 is h (I! It is the sum of
−1 ° k) and h (1 = 2. K), and the amount of transfer 1ikh (2, k) to the speaker 3-2 is h (j! = 3. It
is the sum of k) and h (Il = 4. K). The same applies to the following. As described above, the
transfer function of each speaker is generated according to the number and arrangement of the
speakers of the reproduction system from the transfer function including the directional
information of the unique sound field, whereby the arrangement and the number of the
reproduction system speakers are Even if the number of directions of arrival of sound in the
sound field to be reproduced and the way of determining the area do not match, it is possible to
provide a system that allows the listener to experience the sound almost the same as in the room
to be reproduced. [Effects of the Invention] As described above, according to the present
invention, direction information is given to the transfer function of the sound field to be
reproduced, and based on the direction information, the direction (speaker) according to the
given configuration of the reproduction system In a method of reproducing a signal obtained by
creating (a convolution operation) transfer functions of each of the transfer functions and a
sound source signal by using direction-specific speakers, a method of creating a transfer function
given direction information ( By standardizing space division and the number of divisions, etc.,
even if the arrangement and the number of reproduction speakers do not match the standard, the
standardized direction information of the reproduction system and the arrangement of
reproduction speakers and Since the reproduction signal of each speaker corresponding to the
reproduction system can be generated by associating the number with the number, it is easy for
the listener to easily experience the sound in the same room as the room to be reproduced. There
is provided Tekiru advantage.
[0002]
Brief description of the drawings
[0003]
1A shows a transfer function h (t), FIG. 1B shows an example of its direction information ff1 (t),
FIG. 2 shows an example of a transfer function according to the arrival direction, and FIG. FIG. 4
is a block diagram showing the configuration of the embodiment of the present invention, FIG. 4
is a diagram showing an example of the number and direction of arrival directions of sound in a
sound field to be reproduced, FIG. 5 is a structure of a reproduction system with a listener FIG. 6
is a block diagram showing an example of the conventional sound field reproduction method.９
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