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JP2008131089

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JP2008131089
An object of the present invention is to provide a sound image feeling that is optimum for a
listener who is located at any listening position without sound leakage to the surroundings.
According to the present invention, a low frequency component signal of a predetermined
frequency or less among multi-channel reproduction signals supplied from a sound source is
outputted to a subwoofer 3 commonly used for a plurality of users U1 to U3 and exceeds a
predetermined frequency. The mid-high range component signal is distributed so as to be output
to the plurality of non-sealed headphones HP1 to HP3 attached to the plurality of users U1 to U3
respectively, and the bass output from the subwoofer 3 according to the low-range component
signal Signal processing taking into consideration the connection of sounds with middle to high
tones output from the plurality of headphones HP1 to HP3 in accordance with the component
signals is performed on each of the channels corresponding to the plurality of headphones HP1
to HP3. [Selected figure] Figure 1
Acoustic system, acoustic apparatus and method for generating optimum sound field
[0001]
The present invention relates to an audio system, an audio apparatus, and an optimal sound field
generation method, and is suitably applied to, for example, a multi-channel reproduction system.
[0002]
Conventionally, in a multi-channel reproduction system that reproduces multi-channel audio
content that is rapidly becoming popular by using a plurality of speakers, the listening positions
of a plurality of listeners located in front of the plurality of speakers are actually different. Only
the listener located at the optimum listening position can obtain the sound image as intended by
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1
the producer, and it is difficult for all the multiple listeners to obtain an accurate sound image
simultaneously.
[0003]
This is self-evident considering the wavelength of the audible range and the size of the human
head, but for example, considering only the positions equidistant from multiple speakers in the
horizontal plane, even the number of channels of about 5 ch, It will be understood from the fact
that this condition is limited to one place.
[0004]
Note that this is based on geometrical elements, and even with electronic sound field correction
means currently being proposed by various companies, correction to obtain an accurate sense of
sound at the same time by all of a plurality of listeners. It is fundamentally impossible to do
[0005]
On the other hand, for reference, in a multi-channel reproduction system, while allowing a
plurality of users to individually listen to audio signals with headphones, simultaneously mixing
the bass components of each audio signal for all users. It has been proposed that the subwoofer
is made to listen to the bass (see, for example, Patent Document 1).
Japanese Patent Application Publication No. 2005-252597
[0006]
By the way, in the multi-channel playback system having such a configuration, it is physically
unavoidable that the listening positions of a plurality of listeners located in front of a plurality of
speakers are different from each other, and the sound image feeling actually according to the
content producer's intention is Only listeners who are located at the optimal listening position
can be obtained, and it is fundamentally impossible to make corrections to obtain an accurate
sound image at the same time, for example, by all the listeners simultaneously. When there is a
scene of an object as if it were a content such as DVD (Digital Versatile Disc) rotating around the
listener, it is possible to properly enjoy the connection of sound images accompanying the
rotation of the object. Only the listeners who are present at the center of the group, and other
listeners who are present around them, enjoy the same connection of sound images. That there is
a problem that can not be.
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2
[0007]
Further, in the multi-channel reproduction system, since the reproduction sound is output using a
plurality of speakers, there is a problem that the reproduction sound can not be output at a loud
volume level for the user in consideration of the influence of the sound leakage. The
[0008]
The present invention has been made in consideration of the above points, and provides an
acoustic system, an acoustic device, and an optimum sound that can provide an optimum sound
image feeling to a listener who is free from surrounding sound and located at any listening
position. It is intended to propose a field generation method.
[0009]
In order to solve such problems, in the present invention, a plurality of non-sealed headphones to
be worn by a plurality of users, a subwoofer commonly used by a plurality of users, and a
predetermined frequency among multichannel reproduction signals supplied from a sound
source Distribution means for outputting the following low-pass component signals to the
subwoofer and outputting a mid-high-pass component signal exceeding a predetermined
frequency to a plurality of non-sealed headphones, and a bass output from the subwoofer
according to the low-pass component signals And signal processing means for performing signal
processing taking into consideration the connection of sounds with medium and high tones
output from a plurality of non-sealed headphones according to the middle and high frequency
component signals to each of the channels corresponding to the plurality of non-sealed
headphones To provide
[0010]
This allows the user to listen to medium to high tones through the non-sealed headphones, and
the bass outputted through the subwoofer from the gap between the ear and the headphone
portion due to the non-sealed structure of the non-sealed headphones In addition to listening to
the sound, it is possible to make the whole body feel vibration due to the bass, so it is possible to
provide the reproduced sound to all the multiple users at a sufficient volume level while greatly
reducing the sound leakage to the surroundings. .
In addition, taking into consideration that the distances between the commonly used subwoofer
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and the plurality of users are different from each other, the signal processing is performed so
that the bass and the mid-high range are connected without a sense of incongruity. It is possible
to provide the user with an optimal sound image.
[0011]
According to the present invention, while allowing the user to listen to middle and high tones
through the non-sealed headphones, the bass outputted through the subwoofer can be in the
form of the non-sealed headphones and the ear and the headphone portion. In addition to
listening from the gaps of the sound, it is possible to make the whole body feel vibration due to
the bass, so the reproduction sound is provided to all the multiple users at a sufficient volume
level while greatly reducing the sound leakage to the surroundings. It is located at any listening
position because it is processed so that the bass and the middle and high tone can be connected
seamlessly without taking into consideration that the distance between the subwoofer commonly
used and the multiple users is different. It is possible to realize an acoustic system, an acoustic
device, and an optimum sound field generation method that can provide an optimum sound
image feeling to the user.
[0012]
Hereinafter, an embodiment of the present invention will be described in detail with reference to
the drawings.
[0013]
(1) First Embodiment First, the most basic first embodiment will be described.
[0014]
(1-1) Overall Configuration of Multi-Channel Reproduction System According to First
Embodiment In FIG. 1, reference numeral 1 generally denotes a multi-channel reproduction
system according to an embodiment of the present invention, in an indoor environment such as
living room. Alternatively, multi-channel audio content such as DVD (Digital Versatile Disc) or
SACD (Super Audio Compact Disc) is intended to be provided to a plurality of users U1 to U3 in a
realistic manner, and the audio device 2 is optional. The subwoofer 3 commonly used for the
plurality of users U1 to U3 located at the listening position and the headphones HP1 to HP3 used
respectively by the plurality of users U1 to U3.
[0015]
(1-2) Basic Circuit Configuration of Multi-Channel Reproduction System According to First
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Embodiment As shown in FIG. 2A, in the multi-channel reproduction system 1, for example, when
only a single user U1 is targeted, After performing predetermined signal processing via the
sound processor 11 on reproduction signals consisting of a plurality of channels reproduced by
the DVD / SACD player 12 of the audio device 2, to the mid-high frequency component signal S1
of them to the headphone HP1 of the user U1 The low-frequency component signal S2 is
distributed so as to be output to the subwoofer 3 while transmitting by wire or wirelessly.
[0016]
The headphone HP1 is configured to output medium-to-high-pitched sound of reproduced sound
from a speaker unit (not shown) attached to the inside of the casings K1 and K2 in response to
the middle to high frequency component signal S1 supplied from the sound processor 11. ing.
[0017]
On the other hand, the subwoofer 3 is designed to output the bass of the reproduced voice
according to the low frequency component signal S2 supplied from the sound processor 11.
As a result, in the multi-channel playback system 1, medium and high tones of the playback voice
are output from the headphone HP1, and a bass of the playback voice is output from the
subwoofer 3, so that the synthesized voice becomes the listening sound for the user U1. It is
done.
[0018]
Here, as the headphone HP1, a so-called closed type rather than a so-called open type is used,
and there is a gap between the ear pads of the housings K1 and K2 and the ear of the user U1. It
is assumed.
[0019]
The open type headphone HP1 is characterized by not giving a feeling of oppression near the ear
of the user U1, who is a listener, and excellent in wearing feeling, etc., but at the same time the
front and back of the diaphragm of the speaker unit Is connected in space, and there is a
drawback that sufficient low frequency reproduction can not be performed because a
cancellation effect occurs in a long wavelength low frequency sound.
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[0020]
However, in this multi-channel reproduction system 1, since the bass of the reproduction sound
can be covered by the subwoofer 3 connected to the sound processor 11 in addition to the open
type headphone HP1, the listener can be provided with the entire frequency band of the
reproduction sound. It is made to be able to listen to it.
[0021]
That is, in the open type headphone HP1, since a gap is opened between the ear pad portions of
the casings K1 and K2 and the ear, the user U1 can listen to the bass outputted from the
subwoofer 3 through the gap become.
[0022]
Further, with regard to the low-frequency reproduction using the subwoofer 3, there are also the
following advantages.
In contents such as movies mainly provided by DVD, the role of low-range expression is often the
reproduction of sound effects representing explosions and a feeling of sealing.
[0023]
It is clear from experience that those powerful effects are greatly affected not only by the lowpitched sound heard from the ear but also by the vibration etc. received over the entire body of
the listener.
In that sense, it is considered that low-frequency reproduction is not limited to the headphone
HP1 alone, but that the spatial reproduction actually performed by the subwoofer 3 can further
convey to the user U1 the powerful force reflecting the content creator's intention.
[0024]
As described above, in the multi-channel reproduction system 1, in addition to the ability to listen
to the bass from the subwoofer 3 through the gap between the ear pad portion and the ear in the
open type headphone HP1, the bass from the subwoofer 3 is the body of the user U1. It is made
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to be able to feel as vibration that is received as a whole.
[0025]
Similarly, as shown in FIG. 2B, in the multi-channel reproduction system 1, in the case where a
plurality of users U1 to U3 are targeted, reproduction of a plurality of channels reproduced by
the DVD / SACD player 12 of the audio device 2 is performed. After predetermined signal
processing is performed on the signal through the sound processor 11, the mid-high frequency
component signals S1A to S1C are transmitted to the headphones HP1 to HP3 of the users U1 to
U3 by wire or wireless respectively, and low frequency components The signal S2 is distributed
so as to be output to the subwoofer 3.
[0026]
In this case, in the sound processor 11, the distances from the subwoofer 3 to the users U1 to U3
are different depending on the difference in listening position, and the frequency characteristics
of the reproduced voice reaching the users U1 to U3 are different from each other. The middle to
high frequency component signals S1A to S1C obtained as a result of time alignment correction
and frequency characteristic correction are respectively output to the headphones HP1 to HP3 of
the users U1 to U3.
[0027]
The headphones HP1 to HP3 output middle to high tones of the reproduced sound from the
respective speaker units (not shown) in the headphones HP1 to HP3 in accordance with the
middle to high frequency component signals S1A to S1C supplied from the sound processor 11,
respectively. It is done.
[0028]
On the other hand, the subwoofer 3 is designed to output the bass of the reproduced voice
according to the low frequency component signal S2 supplied from the sound processor 11.
As a result, in the multi-channel playback system 1, medium to high tones of the playback voice
are output from the headphones HP1 to HP3 and the bass of the playback voice is output from
the subwoofer 3, and the synthesized voice is heard by the users U1 to U3. It is made to be a
sound.
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[0029]
Also in this case, as the headphones HP1 to HP3, not so-called closed type but open type are
used, and in view of the fact that the front and back of the diaphragm of the speaker unit are
connected in space, a long-wave bass There is a drawback that low-frequency reproduction can
not be performed sufficiently to cause cancellation effects at the same time, but since the lowrange can be covered by the subwoofer 3 connected to the sound processor 11, the entire
reproduction frequency range can be Certain users U1 to U3 can be made to listen.
[0030]
As described above, in the multi-channel reproduction system 1, in addition to the ability to listen
to the bass from the subwoofer 3 through the gap between the ear pad portion and the ear in the
open headphones HP1 to HP3, the bass from the subwoofer 3 is used by the user U1. It is made
to be able to feel as vibration received by the whole body of ~ U3.
[0031]
(1-3) Configuration of Headphones in First Embodiment Here, in the headphones HP1 to HP3, as
shown in FIG. 3, a configuration in which one speaker unit SU1 and one speaker unit SU2 are
provided on the left and right of the user U1 is Conceivable.
[0032]
Further, as shown in FIGS. 4A and 4B in which parts corresponding to those in FIG. 3 are denoted
by the same reference numerals, not only the speaker units SU1 and SU2 of the lateral side of the
ear of the head of the user U1 In addition to the speaker units SU3 and SU4 being provided, the
configuration is also conceivable in which the speaker units SU5 and SU6 are provided on both
sides behind the speaker units SU3 and SU4.
[0033]
That is, in this case, the speaker units SU1 to SU6 are arranged so as to wrap from the front, the
side, and the back with respect to the left and right ears of the user U1.
[0034]
(1-4) Sound Image Localization Method in the First Embodiment The speaker units SU1, SU3 and
SU5 are provided in the left ear lateral portion as described above, and the speaker units SU2,
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SU4 and SU6 are provided in the right ear lateral portion. The sound image localization method
in the case of using the headphones HP1 to HP3 (FIG. 4) and the headphones HP1 to HP3
provided with the speaker units SU1 and SU2 respectively on the left ear lateral part and the
right ear lateral part The sound image localization method when 3) is used will be described
respectively.
However, for convenience, only the headphone HP1 among the headphones HP1 to HP3 will be
described here.
[0035]
(1-4-1) Sound image localization method in the case of using headphones provided with a
plurality of speaker units respectively on the left and right sides A plurality of speaker units SU1
to SU6 as shown in FIGS. 4 (A) and 4 (B) In the case of the headphone HP1 having, as shown in
FIG. 5, for example, an L channel for the left front speaker and an R channel for the right front
speaker in 5.1 channel multi-channel audio content reproduced from the DVD 19 which is a 5.1
channel sound source The content creator intends by outputting the audio signals for the C
channel for center speaker, the SL channel for left surround speaker, and the SR channel for right
surround speaker as individual channel audio by individual speaker units SU1 to SU6. Do not
sense the direction of the sound image you made It is designed to be able to give sound image
localization.
[0036]
In this case, for an audio signal output via the C channel for the center speaker, when there is
originally one center speaker and the audio signal for the C channel is output to the speaker
units SU3 and SU4, respectively, for the center speaker Level balance with the other channels (L
channel, R channel, SL channel and SR channel) is broken by the increase of the volume level of
the C channel, so the level reduction circuit is provided before supplying to the speaker units SU3
and SU4. 21 and 22 respectively reduce the gain by -3 [dB].
[0037]
In addition, the low frequency component signal supplied to the LFE (Low Frequency Effect)
channel is originally output to the subwoofer 3 as usual since it corresponds to a frequency band
in a range where the user does not give a sense of direction to the sound image. It is done.
[0038]
That is, in the multi-channel reproduction system 1 in this case, medium to high sound which can
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give a sense of direction of the sound image among the reproduced sound corresponding to the
multi-channel audio content is individually through the headphone HP1 having a plurality of
speaker units SU1 to SU6. By making it output, even if it is for the listener located at any listening
position, for the scene of the object as if it rotates around the listener, this object rotates It is
designed to make you feel the sense of direction of the accompanying sound image.
[0039]
(1-4-2) Sound image localization method in the case of using headphones provided with one
speaker unit on the left and one on the left and one right ear as shown in FIG. 3 In the case of the
headphone HP1 provided with the units SU1 and SU2, as shown in FIG. 6, in the multi-channel
reproduction system 1, from the speaker units SU1 and SU2 provided inside the left and right
cases K1 and K2 of the headphone HP1. To make the listener feel that the sound image of the
sound to be reproduced is emitted from virtual left channel VL, virtual right channel VR, virtual
center channel VC, virtual surround left channel VSL, and virtual surround right channel VSR It
needs to be localized.
[0040]
Then, in the multi-channel reproduction system 1, the reproduction sound emitted from the left
and right speaker units SU1 and SU2 in the headphone HP1 is the virtual left channel VL, the
virtual right channel VR, the virtual center channel VC, the virtual surround left channel VSL,
Since it can be felt as if it is emitted from the virtual surround right channel VSR, stereoscopic
effect and presence for a user listening to multi-channel audio content such as DVD via the
monitor 4 (FIG. 1) It is designed to be able to provide a sense of reproduction sound.
[0041]
Here, the principle of the sound localization processing for moving the sound image will be
described.
As shown in FIG. 7, a virtual left channel VL, a virtual right channel VR, and a virtual center
which attempt to localize a sound image for a listener who will be present at the position of the
dummy head DH in a predetermined reproduction sound field. The left speaker SL, the right
speaker SR, the center speaker SC, the left surround speaker SSL, and the right surround speaker
SSR are actually arranged at virtual speaker positions of the channel VC, the virtual surround left
channel VSL, and the virtual surround right channel VSR.
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[0042]
Then, the reproduction sound emitted from the left speaker SL, the right speaker SR, the center
speaker SC, the left surround speaker SSL, and the right surround speaker SSR is collected by
both ears of the dummy head DH, and the left speaker SL, the right speaker SR , The center
speaker SC, the left surround speaker SSL, and the head sound transfer function (K) showing how
the reproduced sound emitted from the right surround speaker SSR changes when it reaches
both ears of the dummy head DH The HRTF (Head Related Transfer Function) is measured in
advance.
[0043]
In this case, the head sound transfer function of the reproduced sound from the left speaker SL
to the left ear of the dummy head DH is N11, and the head sound transfer function of the
reproduced sound from the left speaker SL to the right ear of the dummy head DH is N12 It is.
[0044]
Similarly, the head sound transfer function of the reproduced sound from the center speaker SC
to the left ear of the dummy head DH is N21, and the head sound transfer function of the
reproduced sound from the center speaker SC to the right ear of the dummy head DH is N22 It is.
[0045]
The head acoustic transfer function of the reproduced sound from the right speaker SR to the left
ear of the dummy head DH is N31, and the head acoustic transfer function of the reproduced
sound from the right speaker SR to the right ear of the dummy head DH is N32 is there.
[0046]
Furthermore, the head sound transfer function of the reproduced sound from the left surround
speaker SSL to the left ear of the dummy head DH is N41, and the head sound transfer function
of the reproduced sound from the left surround speaker SSL to the right ear of the dummy head
DH is N42. The head sound transfer function of the reproduced sound from the right surround
speaker SSR to the left ear of the dummy head DH is N51, and the head sound transfer function
of the reproduced sound from the right surround speaker SSR to the right ear of the dummy
head DH is It is N52.
[0047]
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As described above, if signal processing is performed using the head acoustic transfer function N
measured in advance and the reproduced sound corresponding to the sound signal after the
signal processing is emitted, the sound is emitted from the speaker units SU1 and SU2 of the
headphone HP1. To make the listener feel that the playback audio to be heard is emitted from
the virtual speaker position of virtual left channel VL, virtual right channel VR, virtual center
channel VC, virtual surround left channel VSL, virtual surround right channel VSR Can localize
the sound image.
[0048]
Incidentally, although the case of using the dummy head DH when measuring the head acoustic
transfer function N has been described, the present invention is not limited thereto, and a human
is actually seated and a microphone is placed near the human ear The head acoustic transfer
function N may be determined by measurement or by simulation.
[0049]
Specifically, as shown in FIG. 6, the audio signal of 5.1 ch reproduced from the DVD 19 which is
a 5.1 ch sound source is a terminal T1 for the left channel, a terminal T2 for the center channel, a
terminal T3 for the right channel, It is supplied for each channel via the surround left channel
terminal T4, the surround right channel terminal T5, and the LFE channel terminal T6.
[0050]
The audio signal of L channel input through the left channel terminal T1 is output to the sound
image localization processing filters 21 and 22, and the audio signal of C channel input through
the center channel terminal T2 is sound image localization processing The R channel audio signal
output to the filters 23 and 24 and input through the right channel terminal T3 is output to the
sound image localization processing filters 25 and 26, and SL input through the surround left
channel terminal T4. The audio signal of the channel is output to the sound image localization
processing filters 27 and 28, and the audio signal of the SR channel input through the surround
right channel terminal T5 is output to the sound image localization processing filters 29 and 30.
[0051]
The sound image localization processing filter 21 performs signal processing with the head
acoustic transfer function "N11" on the L channel audio signal supplied via the left channel
terminal T1, and sends this to the adder 31. .
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The sound image localization processing filter 22 also performs signal processing with the head
acoustic transfer function "N12" on the L channel audio signal supplied via the left channel
terminal T1, and sends it to the adder 32. Do.
[0052]
The sound image localization processing filter 23 performs signal processing by the head
acoustic transfer function “N21” on the audio signal of the C channel supplied via the center
channel terminal T 2, and sends this to the adder 31. .
The sound image localization processing filter 24 also performs signal processing with the head
acoustic transfer function "N22" on the C channel audio signal supplied via the center channel
terminal T2 and sends it to the adder 32. Do.
[0053]
The sound image localization processing filter 25 performs signal processing by the head
acoustic transfer function “N31” on the R channel audio signal supplied via the right channel
terminal T3 and sends it to the adder 31. .
The sound image localization processing filter 26 also performs signal processing with the head
acoustic transfer function "N32" on the R channel audio signal supplied via the right channel
terminal T3 and sends it to the adder 32. Do.
[0054]
The sound image localization processing filter 27 performs signal processing by the head
acoustic transfer function "N41" on the audio signal of the SL channel supplied via the surround
left channel terminal T4, and sends it to the adder 31. Do.
Further, the sound image localization processing filter 28 also performs signal processing by the
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head acoustic transfer function “N42” on the audio signal of the SL channel supplied via the
surround left channel terminal T 4, and sends it to the adder 32. Send out.
[0055]
The sound image localization processing filter 29 performs signal processing by the head
acoustic transfer function “N51” on the audio signal of the SR channel supplied via the
surround right channel terminal T5, and then transmits this to the adder 31. Do.
Further, the sound image localization processing filter 30 also performs signal processing with
the head acoustic transfer function “N52” on the audio signal of the SR channel supplied via
the surround right channel terminal T5, and then adds this to the adder 32. Send out.
[0056]
The adder 31 adds the audio signals of the respective channels respectively supplied from the
sound image localization processing filter 21, the sound image localization processing filter 23,
the sound image localization processing filter 25, the sound image localization processing filter
27 and the sound image localization processing filter 29. The resultant composite signal is sent
to the transaural filter 33.
[0057]
The adder 32 adds the audio signals of the respective channels respectively supplied from the
sound image localization processing filter 22, the sound image localization processing filter 24,
the sound image localization processing filter 26, the sound image localization processing filter
28 and the sound image localization processing filter 30 The resultant composite signal is sent to
the transaural filter 34.
[0058]
Here, the transaural filters 33 and 34 are used even if the sound image localization processing is
performed on the reproduced sound emitted from the speaker units SU1 and SU2 of the
headphone HP1 by the sound image localization processing filters 21 to 30, In some cases, due
to the influence of head acoustic transfer functions “G1” and “G2” from the actual speaker
units SU1 and SU2 to the ear, the sound image of the reproduced sound may not be localized at
the intended virtual speaker position It is.
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[0059]
Therefore, the transoral filters 33 and 34 are used to multiply the combined signals output from
the adders 31 and 32, respectively by 1 / "G1" and 1 / "G2", and left and right from the speaker
units SU1 and SU2. The speaker units SU1 and SU2 of the headphone HP1 are output by
outputting the composite signal after correction obtained by removing the influence of the
transfer functions “G1” and “G2” to the ear to the speaker units SU1 and SU2 of the
headphone HP1. It is possible to accurately localize the reproduced sound emitted from the left
speaker SL, the right speaker SR, the center speaker SC, the left surround speaker SSL, and the
right surround speaker SSR at the virtual speaker position as if it were emitted from the left
speaker SL, It is done.
[0060]
Therefore, also in this case, the user U1 using the headphone HP1 can be made to feel as if the
reproduction sound emitted from the speaker units SU1 and SU2 of the headphone HP1 can be
heard from the virtual speaker position. Since it can be performed, the sense of direction of the
sound image accompanying the rotation of the object with respect to the scene of the object as if
it is rotating around the listener, even for the listener located at any listening position. Is made to
be able to make the listener feel it.
[0061]
In this case, low-frequency component signals unrelated to sound image localization are supplied
to the subwoofer 3 via the LFE channel terminal T6, and the subwoofer 3 emits the low-pitched
portion of the reproduced sound. .
[0062]
Thus, the sound image localization method in the case of using the headphones HP1 to HP3
provided with the speaker units SU1, SU3 and SU5 in the left ear lateral part and the speaker
units SU2, SU4 and SU6 in the right ear lateral part, As intended by the content producer,
whatever the sound image localization method is in the case of using the headphones HP1 to
HP3 provided with the speaker units SU1 and SU2 respectively in the left ear lateral part and the
right ear lateral part It is made to be able to give a sense of direction of the sound image.
[0063]
(1-5) Specific Circuit Configuration of Multi-Channel Reproduction System in First Embodiment
The basic configuration of the multi-channel reproduction system 1 in the first embodiment of
the present invention has been described. A more realistic application utilizing the present
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invention will be described.
[0064]
In the multi-channel reproduction system 1 described above, the listener listens to the
synthesized sound of both reproduction sounds output from the headphones HP1 to HP3 and the
subwoofer 3 in all cases. If the gain (volume), the delay (delay), and the cross curve
(characteristics / behaviors near both reproduction limit frequencies) of the listener's ear are
significantly different from each other, the connection between the two sounds becomes worse.
[0065]
As a result, the phenomenon that only one of the two reproduced voices can be heard, the
phenomenon that the two reproduced voices are separated and heard, and the phenomenon that
the sound level of the predetermined frequency band falls within the reproduction band is not
heard (dip) A phenomenon (peak) or the like in which only the sound level in the predetermined
frequency band sharply rises is generated, which causes the listener to feel uncomfortable.
[0066]
Furthermore, as shown in FIG. 1, when listening by a plurality of users U1 to U3, since the
positional relationship between the subwoofer 3 and the headphones HP1 to HP3 is different for
each of the users U1 to U3, a spatial factor ( Depending on the distance, the reflection of the wall,
the standing wave, the type of headphones, etc., the respective characteristics are different, and
the problem is further increased.
Therefore, in the present invention, the problems as described above are solved by configuring
systems as shown in FIGS.
[0067]
(1-5-1) Multi-Channel Reproduction System Using Headphones in which Multiple Speaker Units
are Provided As shown in FIG. 8, headphones HP1 to HP3 in which a plurality of speaker units
SU1 to SU6 are provided (FIG. 4) ) Outputs the low frequency component signal SWS of the LFE
channel, which is supplied from the decoder 41 and configures the 5.1 channel multichannel
audio content, to the subwoofer 3, while the left speaker audio of the L channel is output. Signal
LS, right speaker audio signal RS of R channel, center speaker audio signal CS of C channel, left
surround audio signal SLS of SL channel, right surround audio signal SRS of SR channel for
10-05-2019
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headphone HP1 correction unit 42, headphone HP2 Correction unit 43 It is sent to the
correction unit 44 for the headphone HP3.
[0068]
The headphone HP1 correction unit 42 transmits the audio signals (LS, RS, CS, SLS, SRS) of each
channel to the HP1 gain adjustment circuit 42A, the HP1 filter 42B, and the HP1 delay
adjustment circuit 42C from the subwoofer 3 After adjusting the sound pressure level through
the HP1 power amplifier 42D after adjusting the suitable gain, filter characteristics (equalizer,
low pass filter, etc.) and delay corresponding to the distance to the user U1 of the headphone
HP1, the headphones of the user U1 Output high and middle tones of multi-channel audio
content via HP1.
[0069]
Similarly, in the headphone HP2 correction unit 43, the audio signals (LS, RS, CS, SLS, SRS) of
each channel are output to the HP2 gain adjustment circuit 43A, the HP2 filter 43B, and the HP2
delay adjustment circuit 43C. The user adjusts the sound pressure level through the HP2 power
amplifier 43D after adjusting the suitable gain, filter characteristics (equalizer, low-pass filter,
etc.) and delay corresponding to the distance from the subwoofer 3 to the user U2 of the
headphone HP2. Output middle-high tone of multi-channel audio content via the headphone HP2
of U2.
[0070]
Of course, the headphone HP3 correction unit 44 similarly transmits the audio signals (LS, RS,
CS, SLS, SRS) of each channel to the HP3 gain adjustment circuit 44A, the HP3 filter 44B, and the
HP3 delay adjustment circuit 44C. After adjusting the sound pressure level via the HP3 power
amplifier 44D, adjusting the suitable gain, filter characteristics (equalizer, low pass filter, etc.) and
delay corresponding to the distance from the subwoofer 3 to the user U3 of the headphone HP3
The middle and high tone of the multi-channel audio content is output via the headphone HP3 of
the user U3.
[0071]
In the multi-channel reproduction system 40 in this case, subwoofers for the audio signals (LS,
RS, CS, SLS, and SRS) of each channel are corrected by the correction units 42 to 44 for the
headphones HP1 with respect to the headphones HP1 to HP3. After adjusting the suitable gain,
filter characteristics (equalizer, low pass filter, etc.) and delay corresponding to the distance from
3 to the users U1 to U3 of the headphones HP1 to HP3, respectively via the headphones HP1 to
HP3 of the users U1 to U3 By outputting the middle and high tones of the multi-channel audio
10-05-2019
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content, it is possible to give all of the users U1 to U3 a suitable sense of direction of the sound
image.
[0072]
At this time, in the multi-channel reproduction system 40, at the same time, all of the users U1 to
U3 can listen to the bass sound unrelated to the directionality from the common subwoofer 3, so
the listening positions of the users U1 to U3 Regardless, all users U1 to U3 are designed to be
able to listen to sufficient bass not only from their ears but also the entire body.
[0073]
(1-5-2) A multi-channel reproduction system for bus management application using headphones
provided with a plurality of speaker units As shown in FIG. 9 in which corresponding parts to
FIG. The multi-channel reproduction system 50 using the headphones HP1 to HP3 (FIG. 4)
provided with the units SU1 to SU6 has a configuration in which so-called bus management is
applied to the multi-channel reproduction system 40 (FIG. 8) described above. It is a thing.
[0074]
Here, bus management refers to, for example, a system in which a large number of speaker
devices such as a left speaker, a center speaker, a right speaker, a left surround speaker, and a
right surround speaker are provided. To make listeners feel uncomfortable, so let the bass be
output only from the subwoofer, and let other speakers output only middle and high tones
without outputting bass at all. Is a technology to prevent low frequency interference in advance.
[0075]
In a system to which this bus management is applied, when a small speaker other than the
subwoofer is a small-sized speaker, it is possible to stop the low-pitched speaker from outputting
the low-pitched speaker and output the bass only from the subwoofer. It is designed to be able to
prevent destruction in advance.
[0076]
In practice, in the multi-channel reproduction system 50 to which bus management is applied,
the low-pass component signal SWS of the LFE channel constituting the 5.1 ch multi-channel
audio content supplied from the decoder 41 is output to the addition circuit 53 while L The left
speaker audio signal LS of the channel, the right speaker audio signal RS of the R channel, the
center speaker audio signal CS of the C channel, the left surround audio signal SLS of the SL
channel and the right surround audio signal SRS of the SR channel respectively The signal is sent
10-05-2019
18
to the gain adjustment circuit 51 and the middle-high-tone separation high-pass filter 53,
respectively.
[0077]
The bass separation low-pass filter / gain adjustment circuit 51 separates only low-pass
component signals of the audio signals (LS, RS, CS, SLS, SRS) of each channel supplied from the
decoder 41 with a low-pass filter, and performs gain adjustment. And mixing the respective
channels to generate a synthesized low-pass component signal ML 1, which is sent to the
addition circuit 52.
[0078]
The addition circuit 52 adds the low-frequency component signal SWS for the LFE channel
supplied from the decoder 41 and the synthesized low-frequency component signal ML1, and
outputs the resulting low-frequency signal LLS1 to the subwoofer 3. The subwoofer 3 is designed
to be able to output all bass portions of multi-channel audio content.
[0079]
On the other hand, the middle-high-tone separation high-pass filter 53 separates only middlehigh-range component signals of the audio signals (LS, RS, CS, SLS, SRS) of each channel supplied
from the decoder 41 by a high-pass filter The mid-high frequency component signal for each
channel is sent out to the headphone HP1 correction unit 42, the headphone HP2 correction unit
43 and the headphone HP3 correction unit 44 respectively.
[0080]
In the headphone HP1 correction unit 42, the mid-high frequency component signal for each
channel is set to the distance from the subwoofer 3 to the user U1 of the headphone HP1 via the
HP1 gain adjustment circuit 42A, the HP1 filter 42B, and the HP1 delay adjustment circuit 42C.
After adjusting the sound pressure level via the HP1 power amplifier 42D by adjusting the
corresponding suitable gain, filter characteristics (equalizer, low pass filter, etc.) and delay, the
multi-channel audio content of the user U1 via the headphone HP1 The middle and high tone
parts are output from the plurality of speaker units SU1 to SU6 for each channel.
[0081]
Similarly, in the headphone HP2 correction unit 43, the subwoofer 3 to the headphone U2 user
U2 via the HP2 gain adjustment circuit 43A, the HP2 filter 43B, and the HP2 delay adjustment
circuit 43C in the mid-high frequency component signal for each channel. After adjusting the
10-05-2019
19
sound pressure level through the HP2 power amplifier 43D by adjusting the suitable gain, filter
characteristics (equalizer, low pass filter, etc.) and delay corresponding to the distance, the multichannel through the headphone HP2 of the user U2 The mid-high range part of the audio
content is output for each channel from the plurality of speaker units SU1 to SU6.
[0082]
Of course, in the headphone HP3 correction unit 44, similarly, the user U3 of the subwoofer 3 to
the headphone HP3 from the subwoofer 3 via the HP3 gain adjustment circuit 44A, the HP3
filter 44B, and the HP3 delay adjustment circuit 44C. After adjusting the sound pressure level via
the HP3 power amplifier 44D by adjusting the suitable gain, filter characteristics (equalizer, low
pass filter, etc.) and delay corresponding to the distance to the end, multi-user via the headphone
HP3 of the user U3 The mid-high range part of the channel audio content is output for each
channel from the plurality of speaker units SU1 to SU6.
[0083]
In the multi-channel reproduction system 50 to which the bus management in this case is
applied, for the headphones HP1 to HP3, the audio signals (LS, RS, CS, SLS, SRS) of each channel
are corrected by the correction units 42 to 44 for the headphone HP1. The user adjusts the
suitable gain, filter characteristics (equalizer, low pass filter, etc.) and delay corresponding to the
distance from the subwoofer 3 to the users U1 to U3 of the headphones HP1 to HP3 with respect
to the middle to high frequency component signal. By outputting only middle-to-high-pitched
sound of multi-channel audio content via the headphones HP1 to HP3 of U1 to U3, it is possible
to give a suitable sense of direction of a sound image to all the users U1 to U3.
[0084]
At this time, in the multi-channel reproduction system 50, at the same time, all users U1 to U3
can listen to a low frequency unrelated to the directionality from the common subwoofer 3, so
the listening positions of the users U1 to U3 Regardless, all users U1 to U3 are designed to be
able to listen to sufficient low tones not only from the ear but also the entire body.
[0085]
In addition, in the multi-channel playback system 50, since bass management is applied, only the
subwoofer 3 is output for bass, and only middle to high tones are output from the headphones
HP1 to HP3 without outputting any bass. By doing this, it is possible to reliably prevent
interference when bass is output from each speaker.
10-05-2019
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[0086]
Further, in the multi-channel reproduction system 50, although the size of the speaker units SU1
to SU6 in the headphones HP1 to HP3 is very small, the concept of bus management is applied,
and stopping outputting bass from the speaker units SU1 to SU6 is stopped. Since the bass can
be output only from the subwoofer 3, distortion of the output of the speaker units SU1 to SU6
and destruction of the speaker units SU1 to SU6 can be prevented in advance.
[0087]
(1-5-3) A multi-channel reproduction system using headphones in which one speaker unit is
provided on each side, as shown in FIG. 10, in which parts corresponding to those in FIG. In the
multi-channel reproduction system 60 using the headphone HP1 (FIG. 3) in which the speaker
units SU1 and SU2 are provided one by one, the low band for the LFE channel constituting the
5.1 ch multi-channel audio content supplied from the decoder 41 The component signal SWS is
output to the subwoofer 3, while the left speaker audio signal LS of the L channel, the right
speaker audio signal RS of the R channel, the center speaker audio signal CS of the C channel, the
left surround audio signal SLS of the SL channel, and the SR channel Virtual surround processing
of the right surround audio signal SRS Send to the downmix processing circuit 61.
[0088]
The virtual surround processing / downmix processing circuit 61 applies sound image
localization to the sound signals (LS, RS, CS, SLS, SRS) of each channel supplied from the decoder
41 according to the above-described sound image localization method (FIGS. 7 and 8) The virtual
surround signal processing is performed by the localization processing filter 21, the sound image
localization processing filter 23, the sound image localization processing filter 25, the sound
image localization processing filter 27 and the sound image localization processing filter 29, and
the 5.1ch multi-channel audio content is a speaker unit of 2ch Downmix processing is performed
to match headphones HP1 consisting of SU1 and SU2, and the resulting downmix signals DMS
for 2 channels are respectively sent to the correction unit 62 for headphone HP1, the correction
unit 63 for headphones HP2, and the correction unit 64 for headphones HP3. Send out
[0089]
The headphone HP1 correction unit 62 copes with the distance from the subwoofer 3 to the user
U1 of the headphone HP1 with respect to the downmix signal DMS via the HP1 gain adjustment
circuit 62A, the HP1 filter 62B, and the HP1 delay adjustment circuit 62C. Adjust the sound
pressure level by adjusting the suitable gain, filter characteristics (equalizer, low pass filter, etc.)
and delay, and adjust the sound pressure level via the HP1 power amplifier 62D, then, among the
multi-channel audio content via the headphone HP1 of the user U1. High sound is output from
the speaker units SU1 and SU2 on two channels.
10-05-2019
21
[0090]
Similarly, in the headphone HP2 correction unit 63, for the downmix signal DMS, from the
subwoofer 3 to the user U2 of the headphone HP2 via the HP2 gain adjustment circuit 63A, the
HP2 filter 63B, and the HP2 delay adjustment circuit 63C. After adjusting the suitable gain
corresponding to the distance, filter characteristics (equalizer, low pass filter, etc.) and delay, and
adjusting the sound pressure level through the HP2 power amplifier 63D, multi-channel audio
through the headphone HP2 of the user U2 The middle and high sound of the content is output
from the speaker units SU1 and SU2 on two channels.
[0091]
Of course, the correction unit 64 for the headphone HP3 similarly applies to the subwoofer 3 to
the user U3 of the headphone HP3 via the HP3 gain adjustment circuit 64A, the HP3 filter 64B,
and the HP3 delay adjustment circuit 64C for the downmix signal DMS. After adjusting the sound
pressure level through the power amplifier 64D for HP3 and adjusting the suitable gain, filter
characteristics (equalizer, low pass filter, etc.) and delay corresponding to the distance, the multichannel through the headphone HP3 of the user U3 The medium and high sound of the audio
content is output from the speaker units SU1 and SU2 on two channels.
[0092]
In the multi-channel reproduction system 60 in this case, for the headphones HP1 to HP3, the
correction unit 62 for the headphone HP1 to the correction unit 64 for the headphone HP3
perform the subwoofer 3 to the headphones HP1 to HP3 for the downmix signal DMS. After
adjusting the suitable gain corresponding to the distance to the users U1 to U3, the filter
characteristics (equalizer, low pass filter, etc.) and the delay respectively, the middle to high
sound of multi-channel audio content via the headphones HP1 to HP3 of the users U1 to U3. Are
output from the speaker units SU1 and SU2 on two channels, so that the directionality of a
suitable sound image can be individually given to all the users U1 to U3.
[0093]
At this time, in the multi-channel reproduction system 60, it is possible to simultaneously allow
all the users U1 to U3 to listen to the bass sound unrelated to the directionality from the common
subwoofer 3, so the listening positions of the users U1 to U3 Regardless, all users U1 to U3 are
designed to be able to listen to sufficient low tones not only from the ear but also the entire body.
10-05-2019
22
[0094]
(1-5-4) A multi-channel reproduction system for bus management application using headphones
in which one speaker unit is provided on each side, as shown in FIG. 11, in which the
corresponding parts to those in FIG. In the multi-channel reproduction system 70 using the
headphones HP1 to HP3 (FIG. 3) provided with the speaker units SU1 and SU2 respectively on
the left and right, the above-described bus management is applied to the multi-channel
reproduction system 60 described above. It has a configuration.
[0095]
In practice, in the multi-channel reproduction system 70 to which bus management is applied,
the low-pass component signal SWS of the LFE channel constituting the 5.1 ch multi-channel
audio content supplied from the decoder 41 is output to the addition circuit 74 Virtual surround
processing and down processing of left speaker audio signal LS of channel, right speaker audio
signal RS of R channel, center speaker audio signal CS of C channel, left surround audio signal
SLS of SL channel and right surround audio signal SRS of SR channel It is sent to the mix
processing circuit 61.
[0096]
The virtual surround processing / downmix processing circuit 61 applies sound image
localization to the sound signals (LS, RS, CS, SLS, SRS) of each channel supplied from the decoder
41 according to the above-described sound image localization method (FIGS. 7 and 8) The virtual
surround signal processing is performed by the localization processing filter 21, the sound image
localization processing filter 23, the sound image localization processing filter 25, the sound
image localization processing filter 27 and the sound image localization processing filter 29, and
the 5.1ch multi-channel audio content is a speaker unit of 2ch A downmixing process is
performed to match the headphones HP1 of SU1 and SU2, and the resulting downmix signals
DMS1 and DMS2 (downmix signal DMS for two channels) are sent to the adding circuit 72 and
the middle high-tone separation high-pass filter 71, respectively.
[0097]
The middle and high tone separation high pass filter 71 separates only the middle and high
frequency component signals of the downmix signal DMS supplied from the virtual surround
processing / down mix processing circuit 61 by the high pass filter, and the resultant middle and
high frequency components for two channels The signals are sent to the headphone HP1
correction unit 62, the headphone HP2 correction unit 63 and the headphone HP3 correction
unit 64, respectively.
10-05-2019
23
[0098]
The addition circuit 72 adds the downmix signals DMS1 and DMS2 and sends the resultant
downmix signal DMS to the bass separation low pass filter / gain adjustment circuit 73.
[0099]
The bass separation low-pass filter / gain adjustment circuit 73 separates only the low frequency
component signal of the downmix signal DMS supplied from the addition circuit 72 by the low
pass filter, and adjusts the gain to obtain the downmix low frequency component signal DML1. It
is generated and sent to the adder circuit 74.
[0100]
The addition circuit 74 adds the low-frequency component signal SWS for the LFE channel
supplied from the decoder 41 and the downmix low-frequency component signal DML1, and
outputs the resulting low-frequency signal LLS2 to the subwoofer 3 The subwoofer 3 is designed
to be able to output all bass portions of multi-channel audio content.
[0101]
In the headphone HP1 correction unit 62, the subwoofer 3 to the headphones via the HP1 gain
adjustment circuit 62A, the HP1 filter 62B, and the HP1 delay adjustment circuit 62C with
respect to the mid-high frequency component signal of the downmix signal DMS for two
channels. After adjusting the sound pressure level through the HP1 power amplifier 62D after
adjusting the suitable gain, filter characteristics (equalizer, low pass filter, etc.) and delay
corresponding to the distance to the user U1 of the HP1, the headphone HP1 of the user U1 The
middle and high tones of the multi-channel audio content are output from the speaker units SU1
and SU2 through two channels.
[0102]
Similarly, in the headphone HP2 correction unit 63, the subwoofer for the mid-high frequency
component signal of the downmix signal DMS for 2 ch is also transmitted through the HP2 gain
adjustment circuit 63A, the HP2 filter 63B, and the HP2 delay adjustment circuit 63C. 3 after
adjusting the sound pressure level via the HP2 power amplifier 63D after adjusting suitable gain,
filter characteristics (equalizer, low pass filter, etc.) and delay corresponding to the distance from
the user U2 of the headphone HP2 to the user U2 The medium and high tone of the multichannel audio content is output from the speaker units SU1 and SU2 on two channels via the
headphone HP2.
10-05-2019
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[0103]
Of course, the headphone HP3 correction unit 64 similarly applies the HP3 gain adjustment
circuit 64A, the HP3 filter 64B, and the HP3 delay adjustment circuit 64C to the mid-high
frequency component signal of the downmix signal DMS for 2 ch. The user adjusts the sound
pressure level through the HP3 power amplifier 64D after adjusting the suitable gain, filter
characteristics (equalizer, low pass filter, etc.) and delay corresponding to the distance from the
subwoofer 3 to the user U3 of the headphone HP3. Medium to high sound of multi-channel audio
content is output from the speaker units SU1 and SU2 on two channels via the headphone HP3 of
U3.
[0104]
In the multi-channel reproduction system 70 in this case, with respect to the headphones HP1 to
HP3, the correction unit 62 for the headphone HP1 to the correction unit 64 for the headphone
HP3 perform the middle-high frequency component signal of the downmix signal DMS for two
channels. After adjusting the suitable gain corresponding to the distance from the subwoofer 3 to
the users U1 to U3 of the headphones HP1 to HP3, the filter characteristics (equalizer, low pass
filter, etc.) and the delay, respectively, through the headphones HP1 to HP3 of the users U1 to
U3. By outputting middle and high pitches of the multi-channel audio content from the speaker
units SU1 and SU2 on two channels, it is possible to give a suitable sense of direction of the
sound image to all the users U1 to U3.
[0105]
At this time, in the multi-channel reproduction system 70, at the same time, all of the users U1 to
U3 can listen to a low frequency unrelated to the directionality from the common subwoofer 3,
so the listening positions of the users U1 to U3 Regardless, all users U1 to U3 are designed to be
able to listen to sufficient bass not only from their ears but also the entire body.
[0106]
In the multi-channel reproduction system 70 in this case, since bass management is applied, only
the subwoofer 3 is output for bass, and only middle to high tones are output from the
headphones HP1 to HP3 without any bass being output. By doing this, it is possible to reliably
prevent interference when bass is output from each speaker.
[0107]
Further, in the multi-channel reproduction system 70, although the size of the speaker units SU1
to SU6 in the headphones HP1 to HP3 is very small, the concept of bus management is applied,
and the output of the bass from the speaker units SU1 to SU6 is stopped. Since the bass can be
10-05-2019
25
output only from the subwoofer 3, distortion of the output of the speaker units SU1 to SU6 and
destruction of the speaker units SU1 to SU6 can be prevented in advance.
[0108]
(1-6) Operation and Effects in First Embodiment In the above configuration, in multi-channel
reproduction systems 40, 50, 60 and 70, all of users U1 to U3 are located at any listening
position. Even by using headphones HP1 to HP3 for the energy of sound leakage to the
surroundings by listening to the medium and high tones of multi-channel audio content using
headphones HP1 to HP3 instead of the stationary speakers, respectively. Because the noise can
be reduced significantly, the sound propagation to the surroundings can be sufficiently reduced.
[0109]
In multi-channel reproduction systems 40, 50, 60 and 70, after adjusting the suitable gain, filter
characteristics (such as equalizer and low pass filter) and delay considering the distance from
subwoofer 3 to the listening position of users U1 to U3. Since the users U1 to U3 can individually
listen to the middle to high tones of the multi-channel playback content via the headphones HP1
to HP3, the user listening to the middle to high tones of the multi-channel audio content using
the headphones HP1 to HP3 For U1 to U3, it is possible to individually provide a sound image
feeling as intended by the content producer.
[0110]
At the same time, in the multi-channel playback system 40, 50, 60 and 70, the bass of the multichannel audio content is audiblely listened to via the subwoofer 3 common to all the users U1 to
U3 and the bass vibration is the whole body Can be felt tactilely, so that the force accompanied
by the propagation of body vibration can be felt sufficiently.
[0111]
Furthermore, in multi-channel reproduction systems 40, 50, 60 and 70, suitable gains, filter
characteristics (such as equalizers and low pass filters) and delays are preset and preset taking
into consideration the distance from subwoofer 3 to the listening position of users U1 to U3.
Since the user U1 to U3 can individually listen to medium to high tones of the reproduced sound
of the multi-channel reproduction content through the headphones HP1 to HP3, the bass output
from the subwoofer 3 and the headphones HP1 The medium to high-pitched sound output from
the HP3 is connected smoothly, and it is possible to provide an optimal sound image with high
sound quality to the user positioned at any listening position.
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[0112]
As a result, in the multi-channel reproduction system 40, 50, 60 and 70, the phenomenon that
only one of the low-pitched sound output from the subwoofer 3 and the middle-high-level sound
output from the headphones HP1 to HP3 can be heard The phenomenon of being heard
separately, the phenomenon of becoming inaudible due to the sound level falling in the
predetermined frequency band within the reproduction band (dip), the phenomenon that the
sound level of only the predetermined frequency band becomes sharply high (peak) etc. It is
possible to prevent the listener from feeling uncomfortable.
[0113]
According to the above configuration, multi-channel reproduction systems 40, 50, 60 and 70
have very little sound leakage to the surroundings, and provide an optimum sound image feeling
for users U1 to U3 located at any listening position. As well as being able to listen to the high
quality reproduced sound.
[0114]
(2) Second Embodiment Next, a multi-channel reproduction system according to a second
embodiment will be described.
[0115]
(2-1) Overall Configuration of Multi-Channel Reproduction System in Second Embodiment As
shown in FIG. 12 in which the same reference numerals as in FIG. 1 denote the same parts, 90 is
a multi-channel in the second embodiment as a whole. 11 shows a channel reproduction system,
which intends to provide multi-channel audio contents such as DVD and SACD in a realistic
manner to one or more users U1 to U3 in an indoor environment such as a living room. And an
audio device 2 including a DVD / SACD player 12, a measurement / use speaker 91 commonly
used for a plurality of users U1 to U3 located at an arbitrary listening position, and a nonhermetic type used for a plurality of users U1 to U3. The headphones HP11 to HP13 of FIG.
[0116]
The multi-channel reproduction system 90 includes a headphone correction unit 80 having a
central processing unit (CPU) configuration or a digital signal processor (DSP) configuration
provided inside the sound processor 11, and in the measurement mode, the measurement
sequence engine 81. According to the control of the above, the measurement signal reproduction
block 82 outputs the measurement sound of the bass by the woofer UH of the measurement dual
use speaker 91 via the switch circuit 83.
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27
[0117]
In the headphone HP11 worn by the user U1, the measurement sound of bass is collected by the
noise canceling microphones MH1L and MH1R attached to the housings K11L and K11R, and
the headphone HP12 worn by the user U2 is also The noise measurement microphones MH2L
and MH2R attached to the casings K12L and K12R collect the measurement sound of the bass,
and the noises attached to the casings K13L and K13R even in the headphone HP13 worn by the
user U3 The measuring sound of the bass is collected by the canceling microphones MH3L and
MH3R.
[0118]
In addition, the multi-channel reproduction system 90 outputs medium to high measurement
sound from the headphones HP11 to HP13 from the reproduction headphone adjustment engine
86 via the audio output unit 87, and microphones MH1L and MH1R of the headphone HP11 and
microphone MH2L of the headphone HP12. , MH2R, and microphones MH3L and MH3R of the
headphone HP13 respectively.
[0119]
The measurement sequence engine 81 of the headphone correction unit 80 causes the sound
collection block 84 to receive the measurement result for the measurement sound of the bass
transmitted from the headphones HP11 to HP13 by wire or wirelessly or the measurement result
for the measurement sound of middle and high tone.
[0120]
The measurement sequence engine 81 analyzes the measurement result for the measurement
sound of the bass in the analysis block 85 to recognize and measure how the measurement
sound of the bass was heard at each listening position for each of the headphones HP11 to
HP13. A suitable delay is calculated in consideration of the distance from the dual purpose
speaker 91 to the listening positions of the users U1 to U3.
[0121]
In addition, the measurement sequence engine 81 analyzes the measurement result for the
measurement sound of middle and high sound in the analysis block 85 to recognize how the
measurement sound of middle and high sound can be heard at each listening position for each of
the headphones HP11 to HP13. Then, suitable gain and filter characteristics (equalizer, low pass
filter, etc.) are calculated in consideration of the distance from the measurement / use speaker 91
to the listening positions of the users U1 to U3.
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28
[0122]
The measurement sequence engine 81 sends out these various parameters (delay, gain and filter
characteristics) to the reproduction headphone adjustment engine 86 and sets them in advance.
[0123]
In the reproduction mode, the reproduction headphone adjustment engine 86 of the headphone
correction unit 80 uses the various parameters such as the delay, gain, and filter characteristics
(e.g., equalizer, low pass filter, etc.) calculated in the measurement mode. The audio signal of the
multi-channel audio content supplied from the computer is arithmetically processed, and the
resulting mid-high frequency component signal is output from the audio output block 87 to the
headphones HP11 to HP13 of the respective users U1 to U3 by wire or wirelessly, The low
frequency component signal is output to the woofer UH of the measurement / use speaker 91 via
the switch circuit 83.
[0124]
Thereby, in the multi-channel reproduction system 90, as in the first embodiment, the user U1 to
U3 listening to the reproduction sound of the multi-channel audio content using the headphones
HP11 to HP13 is made to perform any special operation. It is possible to automatically give each
user U1 to U3 the sound image feeling as intended by the content producer without causing the
bass of multi-channel audio content to be the woofer UH of the measurement combined speaker
91 common to all the users U1 to U3. Since it can be made to hear aurally through and the
vibration of the bass can also be tactilely felt in the whole body of the body, it is made to be able
to fully feel the force accompanied by the propagation of the body vibration.
[0125]
Of course, also in the multi-channel reproduction system 90 in this case, suitable gains, filter
characteristics (such as equalizers and low-pass filters), and delays are previously adjusted in
consideration of the distance from the measurement / combination speaker 91 to the listening
positions of the users U1 to U3. In addition, since it is possible to make the users U1 to U3
individually listen to medium to high sound in the reproduced sound of the multi-channel
reproduced content via the headphones HP11 to HP13, the bass output from the woofer UH of
the measurement / use speaker 91 And the middle to high-pitched sound outputted from the
headphones HP11 to HP13 are smoothly connected, and it is possible to provide an optimum
sound image with high sound quality to the user positioned at any listening position.
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[0126]
As a result, in the multi-channel reproduction system 90, only one of the low-pitched sound
output from the woofer UH of the measurement / combination speaker 91 and the middle-highlevel sound output from the headphones HP11 to HP13 separates the two sounds. The
phenomenon that you can hear, the phenomenon that you can not hear due to the sound level
falling in the predetermined frequency band in the playback band (dip), the phenomenon that the
sound level only in the predetermined frequency band sharply rises (peak) etc. It can be
prevented and it does not make the listener feel uncomfortable.
[0127]
Incidentally, in the multi-channel reproduction system 90, in the reproduction mode, it is
possible to output the bass of the multi-channel audio content instead of the subwoofer 3 instead
of using the measurement / combination speaker 91.
[0128]
(2-2) Configuration of Headphones in Second Embodiment The headphones HP11 to HP13 used
in the multi-channel reproduction system 90 are, as shown in FIGS. 13 to 15, one in front of the
left and right ears, respectively. A structure of an ear speaker type in which individual speaker
units SU1 and SU2 are provided is conceivable.
However, since all the structures of the headphones HP11 to HP13 are the same here, only the
headphone HP11 will be described for convenience.
[0129]
Specifically, unlike a general box-shaped speaker device, the headphone HP11 is premised to be
worn on the head of the user like a general headphone, and is roughly divided into a voice signal
converted into a reproduced voice The electroacoustic transducers 102L and 102R and a band
unit 103 for mounting the electroacoustic transducers 102L and 102R on the head of the user
U1 and fixing the electroacoustic transducers 102L and 102R to the head of the user U1.
[0130]
The electroacoustic transducers 102L and 102R are configured centering on case parts 104L
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30
and 104R having a shape in which a sphere is divided into four in the vertical direction.
The housing portions 104L and 104R have flat portions formed on the rear surface side and the
left and right inner sides, respectively, and pad portions 105L and 105R for reducing the side
pressure on the head of the user U1 are attached to the left and right inner portions.
[0131]
Speaker units 107L and 107R for converting audio signals of multi-channel audio content into
reproduced audio are attached to baffle plates 104AL and 104AR which are flat portions on the
rear surface side of housing portions 104L and 104R, and noise canceling is provided.
Microphones MH1L and MH1R are attached.
[0132]
In this case, the headphone HP11 has a structure in which the microphones MH1L and MH1R
for noise canceling are attached at a position closer to the inside of the ear canal of the user U1
than the speaker units 107L and 107R in order to enhance the noise canceling effect
particularly. Have.
[0133]
The speaker units 107L and 107R emit sound by vibrating the diaphragm according to the audio
signal of multi-channel audio content supplied by wire or wireless from the audio output unit 87
(FIG. 12) of the sound processor 11. It is done.
[0134]
Further, tubular ducts 108L and 108R are attached to the baffle plates 104AL and 104AR of the
housing portions 104L and 104R, respectively, in which hollow members having a
predetermined thickness are bent into substantially U-shaped sides.
[0135]
The rear end sides of the tubular ducts 108L and 108R are respectively bent in the leftward and
rightward directions, and holes 108AL and 108AR are respectively provided substantially at the
center of the rear end.
[0136]
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31
The band portion 103 is formed in a substantially arch shape convex upward in accordance with
the shape of a general human head centering on the central portion 103A, and is slidably slidable
with respect to the central portion 103A. The overall length of the headphone HP11 can be
adjusted by adjusting portions 103BL and 103BR to be obtained.
[0137]
Further, the band portion 103 is formed in an arch shape having a diameter smaller than the
shape of a general human head and has elastic force, and the housing portions 104L and 104R
are mounted when mounted on the user U1. When mounted while being spread laterally, the
housing portions 104L and 104R are held in contact with the head of the user U1 in order to
return to the original shape by the action of the elastic force after mounting. It is made to get.
[0138]
The headphone HP11 is configured so as to be substantially symmetrical in the left-right
direction as shown in FIG. 13 to FIG. 15, and therefore, in the following, the electro-acoustic
transducer 102L on the left side is mainly described as an example.
[0139]
In practice, as shown in the left side view of FIG. 16, the headphone HP11 is mounted on the
head 500 of the user U1 after the length of the band portion 103 is adjusted, so that the
headphone HP11 is mounted on the lower end side of the adjustment portion 103BL. The
attached electroacoustic transducer 102L is positioned slightly forward of the pinnae 501L of
the head 500 of the user U1.
[0140]
As a result, the electroacoustic transducer 102L of the headphone HP11 directly causes the
medium to high sound emitted from the speaker unit 107L to reach the inside of the ear canal of
the user U1, and the reflected sound reflected by the cheek or pinna 501L of the user U1. Since
the inside of the ear canal can be reached, natural sound image localization can be given as in the
case of listening through a general stationary speaker.
[0141]
At this time, when the headphone HP11 is properly worn by the user U1, the speaker unit 107L
is positioned slightly ahead of the auricle 501L and the ear canal entrance 502L, and the hole
108AL of the tubular duct 108L is located near the ear canal entrance 502L. It is done like that.
10-05-2019
32
[0142]
Incidentally, since the tubular duct 108L is formed in a substantially U-shaped side, the tubular
duct 108L is configured so as not to enter the ear canal of the user U1.
As a result, the headphone HP11 can be prevented in advance from damaging the inside of the
ear canal by the tubular duct 108L when the user U1 is worn or the like.
[0143]
Here, as the Q1-Q2 cross section in FIG. 16 is shown in FIG. 17, the housing unit 104L forms a
sealed space except the tubular duct 108L in a state where the speaker unit 107L is attached. A
resonant circuit is formed with respect to 107L by the housing portion 104L and the tubular
duct 108L.
[0144]
The tubular duct 108L penetrates the baffle plate 104AL of the casing 104L from the inside of
the casing 104L to reach the vicinity of the ear canal entrance 502L of the user U1.
In practice, the electroacoustic transducer 102L is configured to operate as a bass reflex type
speaker as a whole by causing the tubular duct 108L to function as a bass reflex duct.
[0145]
By the way, in a general bass reflex type speaker, the duct is provided only in the inside of the
housing and is not extended to the outside.
Therefore, for comparison with the electroacoustic transducer 102L, an electroacoustic
transducer 152L as shown in FIG. 18 corresponding to FIG. 17 is assumed.
10-05-2019
33
[0146]
The electro-acoustic conversion unit 152L is configured in the same manner as a general bass
reflex type speaker, and instead of the tubular duct 108L of the electro-acoustic conversion unit
102L only on the inside of the housing unit 104, two tubular ducts 118L and 119L are provided.
The
[0147]
In the case of the electro-acoustic transducer 152L, when the position of the speaker unit 107L
is regarded as a virtual sound source position (hereinafter referred to as a virtual sound source
position) PM, middle-to-high-pitched sound emitted from the speaker unit 107L. When the path
length EM until the user U1 reaches the tympanic membrane 503L and the holes 118AL and
119AL are regarded as the virtual sound source position PL2, they are transmitted in the tubular
duct 118L and 119L and emitted from the holes 118AL and 119AL In comparison with the path
length EL2 until the obtained low frequency reaches the tympanic membrane 503L of the user
U1, the path length EM is approximately equal to the path length EL2.
[0148]
Here, FIG. 19 shows the frequency characteristics of the sound reaching the eardrum 503L by
the conventional electroacoustic transducer 152L.
As shown in FIG. 19, the general bass reflex type electro-acoustic transducer 152L is a medium
bass high frequency sound having a frequency characteristic as shown by the characteristic
curve SM, which is emitted from the speaker unit 107L, and the inside of the tubular duct 118L
and 119L. The low-pitched sound transmitted from the holes 118AL and 119AL and having a
frequency characteristic as shown by the characteristic curve SL2 is transmitted to reach the
tympanic membrane 503L of the user U1.
[0149]
As a result, as shown by the characteristic curve SG2 in which the characteristic curve SM and
the characteristic curve SL2 are combined, the electroacoustic transducer 152L listens to the
user U1 for the reproduced sound in which the sound pressure level in the low tone range in the
characteristic curve SM is increased to some extent. It can be done.
[0150]
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34
On the other hand, in the electroacoustic transducer 102L (FIG. 17) according to the present
invention, when the speaker unit 107L is regarded as the virtual sound source position PM, the
medium to high sound emitted from the speaker unit 107L reaches the eardrum 503L of the
user U1. When the hole 108AL is regarded as the virtual sound source position PL1, the path
length EM until the low sound radiated from the hole 108AL reaches the tympanic membrane
503L of the user U1 when the hole 108AL is regarded as the virtual sound source position PL1.
Clearly, the path length EM> path length EL1.
[0151]
Here, the frequency characteristics of the sound reaching the tympanic membrane 503L by the
electroacoustic transducer 102L are shown in FIG.
Since the electroacoustic transducer 102L is a kind of bass reflex type loudspeaker as described
above, the middle to high frequency sound with frequency characteristics as shown in the
characteristic curve SM radiated from the speaker unit 107L as in the case shown in FIG. The low
frequency sound having a frequency characteristic as shown in the characteristic curve SL1
which is transmitted from the hole portion 108AL and transmitted through the tubular duct
108L is made to reach the tympanic membrane 503L of the user U1.
[0152]
Generally, the distance from the sound source and the sound pressure level are in inverse
proportion to each other.
Here, when the route lengths of the electroacoustic transducer 102L (FIG. 17) and the
electroacoustic transducer 152L (FIG. 18) are compared, the relationship of route length EL1
<route length EL2 is obtained.
[0153]
That is, since the virtual sound source position PL1 of the electroacoustic transducer 102L (FIG.
17) is located closer to the ear canal entrance 502L of the user U1 than the virtual sound source
position PL2 of the electroacoustic transducer 152L (FIG. 18), the tubular duct 108L The low
frequency sound transmitted from the inside through the hole 108AL (virtual sound source
10-05-2019
35
position PL1) can reach the eardrum 503L at a sound pressure level higher than that of the
electroacoustic transducer 152L.
[0154]
That is, as shown in FIG. 21, the characteristic curve SL1 of the bass according to the tubular
duct 108L is compared with the characteristic curve SL2 of the bass according to the tubular
ducts 118L and 119L according to the relation of path length EL1 <path length EL2. Overall
sound pressure level is high.
[0155]
As a result, as shown by the characteristic curve SG1 in which the characteristic curve SM and
the characteristic curve SL1 are combined, the electroacoustic conversion unit 102L has a case
where the sound pressure level of the bass region in the characteristic curve SM is the
electroacoustic conversion unit 152L (characteristic curve It is possible to make the user U1 hear
the reproduced sound of a sufficient sound pressure level up to a relatively low frequency band,
which is higher than SG2).
[0156]
Here, when the characteristic curve SG1 and the characteristic curve SG2 are compared, in the
characteristic curve SG2, the sound pressure level is relatively steeply lowered as it goes to the
bass region side, while in the characteristic curve SG1, the bass region side It can be seen that the
degree of decrease in the sound pressure level that can be taken to move forward is gradual.
[0157]
That is, the electroacoustic conversion unit 102L has a high sound pressure level over a wide
frequency band as compared to the electroacoustic conversion unit 152L, that is, a good
reproduced sound including a sufficient low-pitched sound area to the eardrum 503 of the user
U1. It can be transmitted and listened to.
[0158]
In this case, as shown in FIG. 16 and FIG. 17, the electroacoustic transducer 102L locates the
rear end side of the tubular duct 108L in the vicinity of the ear canal inlet 502L of the user U1,
and the ear canal inlet 502L is completely Does not block.
[0159]
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36
For this reason, the electro-acoustic conversion unit 102L adds to the reproduced sound
combining medium-high-pitched sound output from the speaker unit 107L and the low-pitch
sound radiated from the hole 108AL of the tubular duct 108L, the sound generated around the
user U1 It is possible to reach and hear the eardrum 503L of the user U1 without blocking the
ambient sound).
[0160]
Incidentally, the electro-acoustic transducer 102L has an internal volume of 10 [ml] for the
housing section 104L, an outer diameter of 21 [mm] for the speaker unit 107L, and an effective
vibration radius of 8.5 [mm] for the diaphragm of the speaker unit 107L. ], The equivalent mass
of the vibration system is 0.2 [g], the lowest resonance frequency f0 is 360 [Hz], and the
resonance Q0 is 1.0.
[0161]
The tubular duct 108L has an inner diameter of 1.8 mm, an effective length from the inner end
108BL located in the housing portion 104L of the tubular duct 108L to the hole portion 108AL
of 50 mm, and a surface of the baffle plate 104AL. The distance from the point to the hole
108AL is about 35 [mm].
[0162]
Here, since the tubular duct 108L is formed in a U-shape on the side surface and the hole 108AL
is provided at the center of the rear end, two bass reflex ducts substantially including the upper
half and the lower half are configured. The inner diameter and the effective length are
determined in consideration of the inner diameter (corresponding to about 2.5 [mm] in this case)
when converting the tubular duct 108L into one tubular duct.
[0163]
The actual frequency characteristics of the electroacoustic transducing portion 102L and the
electroacoustic transducing portion 152L were measured using a measurement / simulation jig
imitating human auricle and ear canal, and a characteristic curve SG11 as shown in FIG. In the
case of the acoustic conversion unit 102L) and the characteristic curve SG12 (in the case of the
electroacoustic conversion unit 152L) were obtained.
[0164]
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37
In FIG. 22, the characteristic curve SG11 of the electroacoustic transducer 102L is higher than
the characteristic curve SG12 of the electroacoustic transducer 152L in the low frequency band
of about 500 Hz or less, as in the theoretical frequency characteristic shown in FIG. The sound
pressure level is high.
That is, it is shown that the electroacoustic transducer 102L can actually make the user U1 listen
to a good reproduced sound including a sufficient bass.
[0165]
As described above, when the headphone HP11 is mounted on the head 500 of the user U1, the
speaker unit 107L is positioned slightly away from the external ear canal entrance 502L of the
user U1 to radiate middle and high tones of the reproduced sound and The natural sound image
localization is given by radiating the bass of the reproduced voice from the hole portion 108AL
of the tubular duct 108L which is extended from the portion 104L to the vicinity of the external
ear canal inlet 502L and acts as a bass reflex duct, and a good reproduced voice including the
bass is produced. It is made to be able to listen to the said user U1.
[0166]
(2-3) Sound image localization method in the second embodiment Also in the headphones HP11
to HP13 of the ear speaker type as described above, one speaker unit 107L and one speaker unit
107R are provided for each of the left ear lateral part and the right ear lateral part. The method
is the same as the sound image localization method in the case of using the provided headphones
HP1 to HP3, and therefore the description thereof is omitted here for the sake of convenience.
[0167]
(2-4) Specific Circuit Configuration of Noise Canceling Function in Second Embodiment
Subsequently, to realize the noise canceling function by the sound processor 11 of the multichannel reproduction system 90 in the second embodiment The configuration will be described.
[0168]
The noise canceling processing unit for realizing the noise canceling function is provided inside
the sound processor 11 separately from the headphone correcting unit 80 (FIG. 12) described
above, and the noise canceling processing unit The principle of the general noise canceling that
is being described is first described.
10-05-2019
38
[0169]
At present, a system that actively reduces external noise for headphones, a so-called noise
canceling system, is beginning to spread.
Most of products that have been commercialized are composed of analog circuits, and noise
canceling methods are roughly classified into feedback methods and feed forward methods.
[0170]
Generally, as shown in FIG. 23, in the feedback method, a microphone MH1L is provided inside a
housing (housing) 104L of the headphone HP11, and the microphone MH1L responds to the
external noise NSS collected by the microphone MH1L. By generating reverse phase component
data of the noise data and performing servo control to output a noise cancellation sound
corresponding to the reverse phase component data from the speaker unit 107L, the external
noise NSS invading the housing portion 104L is attenuated. It is done like that.
[0171]
In this case, since the position at which the microphone MH1L is provided is the control point CP
of noise canceling, the position closest to the user U1's ear, ie, the speaker unit 107L, in
consideration of the ability to maximize the noise attenuation effect. A microphone MH1L is
provided near the front of the diaphragm.
[0172]
As shown in FIG. 24, as the noise canceling system 200 of the feedback type to which the
principle of the noise canceling described above is applied, the external noise NSS is collected by
the microphone MH1L, and the noise according to the external noise NSS is generated by the
microphone amplifier 201. After the data is amplified to a predetermined level, it is sent to the
feedback filter 202.
[0173]
The feedback filter 202 generates noise reduction data NRS having a phase opposite to that of
the noise data, amplifies the noise reduction data NRS by the power amplifier 206 to the same
level as the amplitude level of the noise data, and then transmits noise reduction data NRS from
the speaker unit 107L through the driver 207. Output noise cancellation sound according to.
10-05-2019
39
[0174]
Thus, in the noise canceling system 200, the external noise NSS and the noise canceling sound
are added at the control point CP of the noise canceling, and as a result, the external noise NSS is
canceled by the noise canceling sound. It will be output.
[0175]
Meanwhile, in the noise canceling system 200, on the other hand, the audio data S of the multichannel audio content is adjusted from the sound source 203 to the acoustic characteristics
desired by the user via the equalizer 204 and then sent to the addition circuit 205. There is.
[0176]
Therefore, the addition circuit 205 adds the noise reduction data NRS supplied from the feedback
filter 202 and the audio data S of the multi-channel audio content, and the resultant composite
data ADD is obtained from the power amplifier 206 and the driver 207 from the speaker unit
107L. In order to output, the user U1 can listen to only the audio of the multi-channel audio
content in which the external noise NSS has been offset.
[0177]
Incidentally, in such a noise canceling system 200, the transfer function of the power amplifier
206 is indicated by "A", the transfer function of the driver 207 is indicated by "D", and the
transfer functions of the microphone MH1L and the microphone amplifier 201 are "M". The
transfer function of the feedback filter 202 is indicated by “−β”.
[0178]
Similarly, the transfer function of the equalizer 204 multiplied by the audio data S of the multichannel audio content output from the sound source 203 is indicated by “E”, and the space
from the driver 207 to the microphone MH1L at the control point CP of noise canceling is
shown. The transfer function 208 is indicated by "H", and it is assumed that all these transfer
functions are represented in a complex manner.
Further, the external noise NSS is indicated by "N", and the sound pressure of the reproduced
voice reaching the ear of the user U1 who is a listener is indicated by "P".
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40
[0179]
The external noise NSS is transmitted to the inside of the housing 104L of the headphone HP11,
for example, when it leaks as a sound pressure from the gap of the pad portion 105L in the
housing 104L, or the housing 104L vibrates under the sound pressure. As a result, there may be
a case where a sound is transmitted inside the housing 104L.
[0180]
At this time, the sound pressure "P" of the reproduction sound output from the speaker unit
107L of the headphone HP11 is
[0181]
[0182]
Can be expressed by
[0183]
In the equation (1), focusing on the term “N” corresponding to the external noise NSS, the
external noise NSS is attenuated to “1 / (1 + ADHMβ)” corresponding to the coefficient part of
“N”. I understand.
However, in order for the system of equation (1) not to oscillate and operate stably, the equation
[0184]
[0185]
Needs to be established.
In general, the equation (2) can be interpreted as described later, together with "1 << | ADHMβ
10-05-2019
41
|".
[0186]
In the noise canceling system 200 in FIG. 24, the entire transfer function “−ADHMβ” of the
loop portion related to “N” corresponding to the external noise NSS of the feedback loop is
referred to as an open loop, and the characteristic as this open loop is shown in FIG. Expressed
by a Bode diagram shown.
[0187]
In this Bode diagram, the noise reduction signal NRS generated by the open loop at this time is
the most excellent in the noise canceling effect since the gain is the largest at the frequency fc
and the phase is shifted 180 degrees. Show that.
[0188]
Therefore, in order to exert the noise canceling effect effectively, the phase 0 [deg.
When the noise reduction data NRS is in phase with the noise data corresponding to the external
noise NSS, the gain Ga and the gain Gb must be smaller than 0 [dB]. Conversely, when the gain is
0 [dB] or more, the phase 0 [deg.
] And not at least its phase 0 [deg.
It is necessary to at least satisfy at least two conditions that the phase Pa and the phase Pb must
be shifted from the point.
[0189]
If this condition is not satisfied, in the noise canceling system 200, positive feedback is applied to
the feedback loop to cause oscillation (howling).
[0190]
Incidentally, gain Ga and gain Gb indicate gain margin for preventing oscillation, and phase Pa
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42
and phase Pb also indicate phase margin for preventing oscillation. When these gain margin and
phase margin are small Due to individual differences, variations in wearing the headphone HP11,
etc., the risk of causing oscillation increases.
[0191]
That is, since the oscillation condition is determined by the open-loop total transfer function "ADHM.beta.", The transfer function "-.beta." In the feedback filter 202 is set while considering
this characteristic, and the gain margin and the phase margin are as large as possible. It is made
to raise the tolerance of the oscillation (howling) to individual difference by doing.
[0192]
Next, the case where the audio data S of multi-channel audio content from the sound source 203
is reproduced from the headphone HP11 while the above-described noise canceling function is
operated will be described.
[0193]
Here, the audio data “S” means the audio of multi-channel audio content from the sound
source 203, but actually, the sound collected by the microphone MH1L in the housing 104L
(when used as a hearing aid function), The target is anything that should originally be
reproduced with headphones, such as voice (when used as a headset) received via
communication.
[0194]
Focusing on the term of the audio data S in the above equation (1), the transfer function "E" of
the equalizer 204 is
[0195]
[0196]
If the equalizer 204 is set such that the following equation is obtained and this is substituted into
the equation (1), the equation (1) can be expressed by the following equation
[0197]
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43
[0198]
It is expressed as
[0199]
In the equation (4), focusing on the term of the audio data S, “H” is a transfer function
according to the distance from the speaker unit SU1 to the microphone MH1L, “A” is a
transfer function of the power amplifier 206, and “D” is Since it is a transfer function of the
driver 207, it can be seen that the same characteristics as the headphone HP11 having no
normal noise canceling function are obtained.
[0200]
At this time, the equalizer 204 has substantially the same characteristics as the characteristics
(FIG. 25) in the open-loop total transfer function “−ADHMβ” when viewed on the frequency
axis.
[0201]
As described above, in the noise canceling system 200, if the equalizer 204 is set as shown in the
above-mentioned equation (3), the sound data S of multi-channel audio content from the sound
source 203 is output to the headphone HP11 while the noise canceling function is operated.
When reproduced from the above, it is possible to output at the same audio level as the
headphone HP11 which does not have a normal noise canceling function.
[0202]
Specifically, as shown in FIG. 26 in which parts corresponding to those in FIG. 24 are assigned
the same reference numerals, a multi-channel reproduction system 90 having a noise canceling
function using the concept of the above noise canceling system 200 The processor 11 has a
configuration in which a noise canceling processing unit 400 including a CPU or DSP is provided
separately from the headphone correction unit 80 (FIG. 12).
[0203]
In the measurement mode, the multi-channel reproduction system 90 collects the external noise
NSS by the microphone MH1L, amplifies the noise signal corresponding to the external noise NSS
by the microphone amplifier 201 to a predetermined level, and then cancels the noise cancel of
the sound processor 11. It is sent to the ring processing unit 400.
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44
[0204]
The noise canceling processing unit 400 converts the noise signal supplied from the microphone
amplifier 201 into a digital signal by the analog-to-digital converter 401, and sends the resulting
noise data to the analysis / reproduction engine 402 having a CPU or DSP configuration.
[0205]
The analysis and reproduction engine 402 generally controls the automatic measurement and
analysis block 404 and the signal reproduction block 405 based on the control of the state
control block 403, and sends noise data supplied from the analog-to-digital converter 401 to the
automatic measurement and analysis block 404. Do.
[0206]
The automatic measurement and analysis block 404 analyzes noise data and generates noise
reduction data NRS having a phase opposite to that of the noise data, and executes the
processing in the feedback filter 202 and the equalizer 204 described above with reference to
FIG. The noise reduction data NRS obtained as a result is held.
[0207]
Next, in the reproduction mode, the multi-channel reproduction system 90 analyzes the audio
data S of the multi-channel audio content reproduced by the DVD / SACD player 12
corresponding to the sound source 203 (FIG. 24). Send to
[0208]
The signal reproduction block 405 sets the equalizer 204 (FIG. 24) as shown in equation (3) as
described above, and the equalizer 204 equalizes the audio data S of the multi-channel audio
content, and switches it. The signal is sent to the digital analog converter 407 via 406.
[0209]
Then, the automatic measurement analysis block 404 sends out the noise reduction data NRS
calculated in the measurement mode to the digital analog converter 407 via the switch circuit
406.
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45
The digital-to-analog converter 407 adds the noise reduction data NRS and the audio data S of
multi-channel audio content, converts the resulting synthesized data ADD into analog signal to
generate the synthesized signal ADS, and generates the synthesized signal ADS. Output via the
driver 207.
Incidentally, nowadays, there is also a case where a digital composite data ADD is output by a socalled digital amplifier which is directly power driven without passing through the digital analog
converter 407.
[0210]
As a result, in the multi-channel reproduction system 90, noise cancellation processing is
digitally executed via the noise canceling processing unit 400 of the sound processor 11, and
reproduction of clear multi-channel audio content in which only the external noise NSS is
canceled. Only the voice can be listened to by the user U1.
[0211]
(2-5) Operation and Effect in Second Embodiment In the above configuration, multi-channel
reproduction system 90 is installed even when all the users U1 to U3 are located at any listening
position. By using headphones HP11 to HP13 to listen to the middle and high tones of multichannel audio content using headphones HP11 to HP13 instead of speakers of the type, the
energy of sound leakage to the surroundings can be significantly reduced by using headphones
HP11 to HP13 As it can, the sound propagation to the surroundings can be sufficiently reduced.
[0212]
Further, in the multi-channel reproduction system 90, a gain and a filter suitable for each
listening position are collected by collecting and analyzing the medium to high-pitched
measurement sound output from the headphones HP11 to HP13 with each microphone provided
for noise canceling. Since characteristics (equalizers, low-pass filters, etc.) are digitally adjusted, it
is possible to make the users U1 to U3 individually listen to medium-to-high tones in the multichannel playback content via the headphones HP11 to HP13. For the users U1 to U3 who are
listening to middle to high sound of multi-channel audio content using the headphones HP11 to
HP13, it is possible to individually provide a sound image feeling as intended by the content
producer.
[0213]
At this time, in the multi-channel reproduction system 90, if the noise canceling function is
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46
operated, the user U1 to U3 can be provided with an optimal sound impression and the sound of
the clear multi-channel audio content without external noise NSS. Can be listened to.
[0214]
At the same time, in the multi-channel playback system 90, the bass of the multi-channel audio
content can be heard aurally and felt throughout the body through the woofer UH of the
measurement / combination speaker 91 common to all the users U1 to U3. Since it can, it can
also make the force accompanied by the propagation of the body vibration feel more than
enough.
[0215]
Furthermore, in the multi-channel reproduction system 90, after suitably automatically adjusting
in advance a suitable delay taking into consideration the distance from the woofer UH of the
measurement / use speaker 91 to the listening position of the users U1 to U3, through
headphones HP11 to HP13. Since it is possible for the users U1 to U3 to individually listen to
medium to high tones in the audio of multi-channel playback content, the bass output from the
woofer UH of the measurement / use speaker 91 and the middle to high tone output from the
headphones HP11 to HP13 Can be connected smoothly to provide an optimum sound image
feeling to the user located at any listening position.
[0216]
As a result, in the multi-channel reproduction system 90, only one of the low-pitched sound
output from the woofer UH of the measurement / combination speaker 91 and the middle-highlevel sound output from the headphones HP11 to HP13 separates the two sounds. The
phenomenon that you can hear, the phenomenon that you can not hear due to the sound level
falling in the predetermined frequency band in the playback band (dip), the phenomenon that the
sound level only in the predetermined frequency band sharply rises (peak) etc. This can be
prevented and does not make the listener feel uncomfortable.
[0217]
According to the above-described configuration, multi-channel reproduction system 90 has very
little sound leakage to the surroundings, and can provide an optimum sound image feeling for
users U1 to U3 located at any listening position, and also external noise NSS. It is possible to
listen to high-quality reproduced voice with less
[0218]
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(3) Other Embodiments In the above-described first embodiment, the case is described in which
the headphone HP1 is provided with the speaker units SU1 and SU2 for middle and high-pitched
sound on the left and right of the headphone HP1. The present invention is not limited to this,
and a two-way structure may be adopted in which two speaker units for middle sound and high
sound are provided in the left and right housings K1 and K2, respectively.
[0219]
Further, in the first embodiment described above, the HP HP 1 gain adjustment circuit 42 A, HP
1 filter 42 B, HP 1 independent correction unit 42 and 62 for the headphones HP 1 in the multichannel playback system 40, 50, 60 and 70 respectively. The HP2 gain adjustment circuit 43A,
HP2 filter 43B, HP2 delay circuit 43C, and HP2 power amplifier 43D, each of which comprises
the delay circuit 42C and the HP1 power amplifier 42D, and the headphone HP2 correction units
43 and 63 are independent of each other. The headphone HP3 correction units 44 and 64 are
each composed of the HP3 gain adjustment circuit 44A, the HP3 filter 44B, the HP3 delay circuit
44C, and the HP3 power amplifier 44D, which are independent of each other. Akira is not limited
to this, the gain adjustment circuit, a filter, a delay circuit may be composed of a gathered state
as one digital filter intended effects of the power amplifier.
[0220]
Furthermore, in the first embodiment described above, the case where the above-described
various signal processing is performed by the sound processor 11 has been described, but the
present invention is not limited to this and is provided inside the housing of the headphones HP1
to HP3. It may be performed by the signal processing circuit described above.
[0221]
Furthermore, in the second embodiment described above, the headphones HP11 to HP13 having
an ear speaker type structure are described, but the present invention is not limited to this, and
for example, as shown in FIG. In addition to the speaker units 107L and 107R provided in front
of the left and right ears as in the ear speaker type headphone HP11 (FIGS. 13 to 16), speaker
units 107LR and 107RR are provided also behind the left and right ears. Ear headphones HP30
may be used.
[0222]
In this case, as shown in FIG. 28 in which parts corresponding to those in FIG. 5 are assigned the
same reference numerals, L channels for the left front speaker and R channels for the right front
speaker in 5.1ch multi-channel audio content Speaker units 107L and 107R disposed at the front
of the ear, and speaker units 107LR and 107RR disposed at the back of the ear of the C channel,
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48
the SL channel for the left surround speaker, and the audio channel for the SR channel for the
right surround speaker. By outputting as each channel sound according to, it is possible to give
the sense of direction of the sound image more three-dimensionally as intended by the content
producer.
[0223]
In this case, for an audio signal output via the C channel for the center speaker, when the center
speaker is originally one and the audio of the C channel is output to the speaker units 107L and
107R, the center speaker is for the center speaker. Level balance with the other channels (L
channel, R channel, SL channel and SR channel) is broken by the increase of the volume level of
the C channel, so the level reduction circuit is provided before supplying to the speaker units SU3
and SU4. 21 and 22 respectively reduce the gain by -3 [dB].
[0224]
Similarly, when L-channel sound is output from the speaker units 107L and 107LR arranged on
the front and rear of the left ear, the volume level of the sound reaching the left ear is also the L
channel for the left front speaker. Since the level balance with other channels (L channel, R
channel, SL channel and SR channel) is broken by becoming larger, the gain is dropped by -3 [dB]
by the level reduction circuits 411 and 412, respectively. Are
[0225]
The same applies to the right front speaker R channel, and the level reduction circuits 413 and
414 similarly reduce the gain by -3 [dB] at a time.
[0226]
Of course, the present invention is not limited to this, and in addition to arranging the speaker
units before and after the left and right ears, in addition to the front and rear of the left and right
ears, the speaker units are arranged just beside each other A speaker type headphone (not
shown) may be used.
[0227]
Furthermore, in the second embodiment described above, the measurement sound is collected by
the microphones MH1L, MH1R, MH2L, MH2R, MH3L, and MH3R for noise canceling function
attached to the headphones HP11 to HP13, respectively. However, the present invention is not
limited to this, and the measurement sound may be collected respectively by a microphone
attached for hearing aid function and a microphone attached for communication as a headset.
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49
[0228]
Furthermore, in the first and second embodiments described above, although the case of using
the non-hermetic headphones HP1 to HP3 and HP11 to HP13 has been described, the present
invention is not limited to this and the left and right ear As long as it is a structure other than a
closed type having a slight gap, instead of completely closing the periphery of the open type
headphone, an open type headphone having other various shapes and structures such as an
inner ear type may be used.
[0229]
Furthermore, in the second embodiment described above, the noise canceling process is digitally
executed by the analysis reproduction engine 402 provided inside the sound processor 11, but
the present invention is not limited thereto. Not limited to this, noise canceling processing may
be performed in an analog manner.
[0230]
Furthermore, in the above embodiment, the headphones HP1 to HP3 and HP11 to HP13 as nonsealed headphones, the subwoofer 3 as the subwoofer, the woofer UH of the measurement / use
speaker 91, the sound processor 11 as the distribution means and the signal processing means
Describes the case where the multi-channel reproduction system 1, 40, 50, 60, 70, 90 as an
acoustic system is configured according to the present invention, but the present invention is not
limited to this, and is a non-hermetic type composed of various other circuit configurations. The
sound system may be configured by headphones, subwoofers, distribution means and signal
processing means.
[0231]
The audio system, the audio apparatus, and the optimum sound field generation method
according to the present invention are not limited to the indoor environment such as a living
room, but common multi-channel audio contents such as the in-vehicle environment of a vehicle
and the cabin environment of an airplane simultaneously by multiple users. It can be applied to
various applications such as viewing.
[0232]
FIG. 1 is a schematic diagram showing an entire configuration of a multi-channel reproduction
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50
system in a first embodiment.
FIG. 1 is a schematic block diagram showing a basic circuit configuration of a multi-channel
reproduction system in a first embodiment.
It is an approximate line figure showing composition (1) of headphones in a 1st embodiment.
It is a basic diagram which shows the structure (2) of the headphones in 1st Embodiment.
FIG. 6 is a schematic diagram for describing a sound image localization method when
headphones having a plurality of speaker units are used.
It is a basic diagram by which it uses for explanation of the sound image localization method at
the time of using the headphone by which the speaker unit was provided 1 each at right and left.
FIG. 5 is a schematic diagram for describing the principle of sound image localization processing.
FIG. 5 is a schematic block diagram showing a specific circuit configuration (1) of the multichannel reproduction system in the first embodiment.
FIG. 6 is a schematic block diagram showing a specific circuit configuration (2) of the multichannel reproduction system in the first embodiment.
FIG. 6 is a schematic block diagram showing a specific circuit configuration (3) of the multichannel reproduction system in the first embodiment.
FIG. 6 is a schematic block diagram showing a specific circuit configuration (4) of the multichannel reproduction system in the first embodiment.
It is a basic diagram which shows the whole structure of the multichannel reproduction |
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51
regeneration system in 2nd Embodiment.
It is an approximate line perspective view showing the whole composition (1) of headphones of
an ear speaker type.
It is an approximate line perspective view showing the whole composition (2) of headphones of
an ear speaker type.
It is an approximate line perspective view showing the whole composition (3) of headphones of
an ear speaker type.
It is an approximate line side view showing wearing condition (1) of headphones of ear speaker
type.
It is an approximate line top view showing wearing composition (2) of headphones of ear speaker
type.
FIG. 2 is a schematic cross-sectional view showing a general bass reflex type ear speaker type
headphone.
It is a characteristic curve figure showing the frequency characteristic in the conventional bass
reflex type speaker.
It is a characteristic curve figure which shows the frequency characteristic of the headphones of
the ear speaker type used in 2nd Embodiment.
FIG. 6 is a characteristic curve diagram showing theoretical frequency characteristics.
It is a characteristic curve figure which shows the frequency characteristic by measurement.
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FIG. 6 is a schematic cross-sectional view for explaining a noise canceling method of a feedback
method.
FIG. 1 is a schematic block diagram showing an outline of a noise canceling system.
FIG. 6 is a characteristic curve diagram for describing phase margin and gain margin for noise
cancellation.
FIG. 2 is a schematic block diagram showing the configuration of a multi-channel reproduction
system having a noise canceling function.
It is an approximate line side view showing composition of headphones of ear speaker type in
other embodiments.
FIG. 16 is a schematic diagram for describing a sound image localization method when using
headphones provided with a plurality of speaker units in another embodiment.
Explanation of sign
[0233]
1, 40, 50, 60, 70, 90 ...... multi-channel reproduction system, 2 ...... sound device, 3 ...... subwoofer,
4 ......, monitor, 11 ...... sound processor, 12 ...... DVD / SACD player, 21 ∼3030 音 sound image
localization processing filter 31, 32 加 算 adder, 33, 34 ト ラ ン ス transaural filter 41 デ コ ー
ダ decoder 42, 62 補正 correction unit for headphone HP1, 43, 63 ヘ ッ ド ホ ン for headphone
HP2 Correction unit 44, 64: correction unit for headphone HP3, 51, 73: bass separation low-pass
filter / gain adjustment circuit, 53: middle-high-tone separation high-pass filter 53, 61: virtual
surround processing / downmix processing circuit, 62 ... correction unit for headphone HP1, 63
... correction unit for headphone HP2, 64 ... correction unit 6 for headphone HP3 , 71: middlehigh-tone separation high-pass filter, 80: headphone correction unit, 81: measurement sequence
engine, 82: measurement signal reproduction block, 83, 406, 407: switch circuit, 84: sound
collection block, 85 ......... Analysis block, 86 ... Reproduction headphone adjustment engine, 87 ...
Audio output block, 91 ... Measurement and measurement speaker, 200 ... Noise canceling
system, 201 ... Microphone amplifier, 202 ... Feedback filter, 203 ... Sound source 204 Equalizer
205 Adder circuit 206 Power amplifier 207 Driver 400 Noise canceling processing unit 401
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Analog-to-digital converter 402 Analysis reproduction engine 403 State control block, 404 ...
Automatic measurement analysis block, 4 5 ...... signal reproduction block, U1~U3 ...... user,
HP1~HP3, HP11~HP13, HP30 ...... headphones.
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