JP2001057699

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DESCRIPTION JP2001057699
[0001]
TECHNICAL FIELD The present invention corrects, for example, the deviation of the center sound
image and the spread of the asymmetrical sound field which occur in the reproduced sound field
such as a car room or a listening room, and so on, to the listener. The present invention relates to
an audio device that provides sound space.
[0002]
2. Description of the Related Art In a conventional audio apparatus, for example, as shown
schematically in FIG. 17A, speakers 5 and 6 of left and right channels are provided in a
reproduction sound field space 4 such as a listening room. When the listener listens to stereo
music or the like in the front center of the speakers 5 and 6, the center sound image C such as
vocals is localized in front of the listener but is asymmetric with respect to the speakers 5 and 6.
When listening at the position, the center sound image C is biased, and there is a problem that a
natural sound space can not be obtained.
[0003]
Further, as a case where the deviation phenomenon of the center sound image C is likely to
occur, the case of an on-vehicle audio apparatus is known.
Since the on-vehicle audio device is used under the special situation of the interior of a car, as
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shown schematically in FIG. 17B, the speakers 1 and 2 of the left and right channels are car In
general, the case is disposed at an asymmetrical position with respect to the passenger (listener)
in the room 3. For this reason, a problem arises that the center sound image C such as vocals,
which should normally be localized in front of the listener, is biased toward the side of the
speaker 2 disposed at a position close to the listener.
[0004]
In order to improve the deviation of the center sound image in the vehicle interior, there has
been proposed an on-vehicle audio apparatus having a balance adjustment function and a time
alignment function.
[0005]
As shown in FIG. 17 (c), the former audio system equipped with the balance adjustment function
listens more than the output level of the speaker 1 placed at a position farther from the listener
by the amplitude adjustment circuit 7 The output level of the speaker 2 closer to the person is
lowered to adjust the balance of the sound pressure levels of the left and right channels with
respect to the listener so that the center sound image C is localized on the front front side of the
listener.
[0006]
As shown in FIG. 17 (d), in the case of the on-vehicle audio apparatus having the latter time
alignment function, the listener 8 is provided with an audio signal to be supplied to the speaker 2
closer to the listener by the delay circuit 8. By providing a time delay to the audio signal supplied
to the speaker 1 arranged at a position far from the center, the arrival time of the sound of the
left and right channels to the listener is matched, and the center sound image C is made on the
front front side of the listener. It is made to localize.
[0007]
Also, a Head Related Transfer Function (HRTF) correction method is known.
This is to simulate the sound field like a concert hall by simulating the sound field like a concert
hall by controlling the transfer function (amplitude and phase characteristics) of the space up to
the position of the speaker and the listener's ear, or sound image in any direction. It is a
correction method for localization.
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It has been proposed to correct the bias of the center sound image or expand the sound field by
applying this correction method to a car audio system.
[0008]
However, in the audio apparatus having the above-mentioned conventional balance adjustment
function and time alignment function, although the center sound image can be localized on the
front of the listener, It has been difficult to improve the spread of the asymmetrical sound field.
[0009]
In addition, when applying the head-related transfer function correction method, a large-scale
and high-speed signal processing circuit is required because a huge amount of audio signals must
be digitally processed in a very short time. There was a problem of becoming
[0010]
For example, although a FIR (Finite Impulse Response) digital filter is used as a signal processing
circuit for constructing a head-related transfer function, filter coefficients or delays may be used
to sufficiently correct complicated sound field characteristics. Since the number of stages of
elements is extremely large and filter coefficients and delay elements capable of high-speed
processing are required, it is necessary to increase the scale and speed of the signal processing
circuit.
[0011]
Further, there is a problem that even if correction is performed by the head-related transfer
function correction method using a large-scale and high-speed signal processing circuit, the
improvement effect can be obtained only under a limited condition.
For example, if the listener always maintains a stationary state, the transfer function to the left
and right ears including the left and right speakers and the head of the listener does not change,
so the improvement effect under the limited conditions Is obtained.
However, in reality, in a car-mounted audio device, the listener always stands still even if the
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listener moves the head etc. frequently while driving, or even if it is a stationary audio device
installed in a living room etc. Since the transfer function of the sound field space from the left
and right speakers to the listener's ear changes, there is a problem that the head transfer
function can not be quickly followed.
[0012]
The present invention has been made to overcome the problems of the above-mentioned prior
art, and corrects the bias of the center sound image in the reproduced sound field, the spread of
the left and right asymmetric sound field, etc. It is an object of the present invention to provide
an audio device capable of providing a natural sound field space.
[0013]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is
provided with a correction circuit having a predetermined transfer function, and a left channel
and a right channel input audio on which a head transfer function is superimposed. An audio
apparatus for supplying a signal to speakers of a left channel and a right channel arranged in
front of a listener's listening position in a reproduction sound field space through the correction
circuit, wherein the correction circuit is arranged in an anechoic chamber. A first transfer
function characterized by a sound field characteristic of a space between the speaker and the left
ear of the listener when the speaker of the left channel is arranged so as to simulate the
positional relationship in the reproduction sound field space; And the characteristics of the space
between the speaker and the right ear of the listener when the speaker of the left channel is
arranged to simulate the positional relationship in the reproduction sound field space. And the
sound field characteristics of the space between the speaker and the left ear of the listener when
the speaker of the right channel is arranged to simulate the positional relationship in the
reproduced sound field space in the anechoic chamber. The third transfer function to be
characterized, and the sound field of the space between the speaker and the right ear of the
listener when the speaker of the right channel is arranged to simulate the positional relationship
in the reproduced sound field space in the anechoic chamber The fourth transfer function
characterized by the characteristics is set as the correction transfer function obtained by the
inverse matrix of the matrix having the element.
[0014]
According to such a configuration, the correction transfer function of the correction circuit is a
so-called inverse characteristic of the transfer function characterized by the sound field
characteristics of the space between the speakers of both channels and the listener.
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When an input audio signal is supplied to the correction circuit, the correction circuit corrects
the input audio signal so as to suppress the influence of the sound field characteristic, and
supplies the corrected audio signal to the speakers of both channels.
Thereby, the influence of the bias of the center sound image of the sound emitted from the
speaker, the spread of the asymmetrical sound field, and the like are offset by the reproduced
sound field characteristic.
Therefore, the listener can listen to a sound equivalent to the sound reproduced based on the
input audio signal on which the head related transfer function is superimposed when the user
listens in an arbitrary sound field.
[0015]
The audio apparatus according to the present invention further comprises a correction circuit
having a predetermined transfer function, and the input audio signals of the left channel and the
right channel on which the head transfer function is superimposed are transmitted through the
correction circuit to produce reproduced sound field space. An audio device for supplying
speakers in left and right channels arranged in front of a listener's listening position in the inside,
the plurality of spatial regions existing in the predetermined reproduction sound field space, A
first transfer function characterized by a sound field characteristic of a space up to the speaker
and the left ear of the listener when the speaker of the left channel is disposed to simulate the
positional relationship in the reproduced sound field space in the anechoic chamber And the
speaker to the left channel when the speaker of the left channel is arranged to simulate the
positional relationship in the reproduction sound field space in the anechoic chamber, and the
sky to the right ear of the listener And the second transfer function characterized by the sound
field characteristics of the speaker and the speaker and the left ear of the listener when the
speaker of the right channel is arranged in the anechoic chamber by imitating the positional
relationship in the reproduced sound field space. A third transfer function characterized by the
sound field characteristic of the space, and the speaker of the right channel when the speaker of
the right channel is arranged in the anechoic chamber to simulate the positional relationship in
the reproduced sound field space; The correction transfer function obtained by the inverse
matrix of the matrix having the fourth transfer function characterized by the sound field
characteristic of the space up to the ear is predetermined, and the determined correction transfer
function is applied to the plurality of spatial regions. The correction circuit includes storage
means for storing in association, and position detection means for specifying a listener's listening
position in the plurality of spatial regions, and the correction circuit is configured to set the
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upper part of the correction transfer function stored in the storage means. Characterized in that
it is set by the correction transfer functions specified in accordance with the listening position of
the listener detected by the position detecting means.
[0016]
According to such a configuration, when the listening position of the listener changes, the
position detecting means applies a correction transfer function according to the changed
listening position.
As a result, without making the listener aware of the listening position, the playback sound with a
symmetrical sense of expansion is provided.
[0017]
DETAILED DESCRIPTION OF THE INVENTION Embodiments of the audio device of the present
invention will be described below with reference to the drawings.
First Embodiment FIG. 1 is a block diagram showing a configuration of an audio apparatus 9
according to a first embodiment. The audio device of the present invention is not limited to the
use form of a home-use audio device, an on-vehicle audio device, etc., but the on-vehicle audio
device 9 will be described as a preferred embodiment.
[0018]
In FIG. 1, the audio apparatus 9 comprises a head transfer function circuit 10a, a correction
circuit 10b, output amplifiers 11, 12 and two channels of speakers 13, 14 arranged in a
compartment 15. It is done. The speakers 13 and 14 are disposed at left and right positions with
respect to the passenger (listener) 16, for example, at both left and right sides of the front
dashboard in the passenger compartment 15, the front door, and the like.
[0019]
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The head-related transfer function circuit 10a comprises arithmetic circuits a1 to a4 and adder
circuits a5 and a6. These arithmetic circuits a1 to a4 and adder circuits a5 and a6 transmit input
audio signals Lin and Rin. A head-related transfer function is realized that superimposes the same
amplitude-phase characteristics as a listener listens in any sound field.
[0020]
More specifically, a reproduction device as a sound source connected to the in-vehicle audio
device 9, for example, an audio source recorded (recorded) in an arbitrary sound field such as a
concert hall or a recording studio is recorded. The audio signals Lin and Rin of each of the left
and right channels generated by a CD reproducing apparatus or an MD reproducing apparatus
which reproduces a recording medium such as a compact disc (Compact Disc) or an MD (Mini
Disc), as shown in FIG. When the user listens at an arbitrary sound field by adding the outputs of
the arithmetic circuits a1, a2, a3 and a4 set to the transfer functions Ht11, Ht12, Ht21 and Ht22
respectively by the addition circuits a5 and a6. The audio signals SL and SR of the left and right
channels on which the head related transfer functions are superimposed are generated and
output.
[0021]
Here, the arithmetic circuits a1, a2, a3 and a4 are not set to the transfer function from the sound
source to the microphone when only the recording microphone is disposed in an arbitrary sound
field. Actually, the transfer functions Ht11, Ht12, Ht21, and Ht22 of the sound field under the
same environment as the listener listens to the left and right ears including the head are set.
[0022]
That is, each transfer function Ht11, Ht12, Ht21, Ht22 is the sound field characteristic in the
space between the sound source on the left side of the listener and the left ear of the listener, the
sound source on the left side of the listener and the listening Sound field characteristics in the
space with the right ear of the person, sound field characteristics in the space between the right
sound source for the listener and the left ear of the listener, sound source right for the listener
and the right ear of the listener And the inverse of a regular matrix whose elements are the
sound field characteristics in the space of and the above-mentioned head-related transfer
function including the head of the listener is realized.
[0023]
The correction circuit 10b performs a correction process described later on the audio signals SL
and SR to which the head-related transfer function is superimposed when the user listens to an
arbitrary sound field, and generates the correction process. The audio signals L and R of the left
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and right channels to be (output) are supplied to the left and right speakers 13 and 14 through
the output amplifiers 11 and 12, respectively.
[0024]
Although not shown, digital audio signals SL and SR sampled at a predetermined sampling
frequency are supplied to the correction circuit 10b, and the audio of each of the left and right
channels subjected to the above correction processing by digital signal processing. The signals L
and R are converted to analog audio signals by a D / A converter and output to the output
amplifiers 11 and 12.
[0025]
Next, the internal configuration of the correction circuit 10b will be described in detail.
The correction circuit 10 b is provided with arithmetic circuits 17 to 20 formed of an IIR (Infinite
Impulse Response) digital filter for performing the correction process.
[0026]
The arithmetic circuits 17 and 18 receive the audio signal SL, and the arithmetic circuits 19 and
20 receive the audio signal SR.
Then, the adder 21 adds the outputs of the arithmetic circuits 17 and 19 to generate an audio
signal L of the left channel, and the adder 22 adds the outputs of the arithmetic circuits 18 and
20 to generate the audio of the right channel. Generate a signal R.
[0027]
Each arithmetic circuit 17 to 20 suppresses the influence of the sound field characteristic in the
vehicle compartment 15 until the sound emitted from the speakers 13 and 14 reaches the left
and right ears 16L and 16R of the listener 16. The transfer function (hereinafter referred to as a
corrected transfer function) H11, H12, H21, H22 to be obtained is constructed, and is designed
by the method described next.
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[0028]
First, as shown in FIG. 2, the dummy listener 16 and the left and right speakers 13 and 14 are
disposed in the anechoic chamber 23 in a state where the positional relationship in the
passenger compartment 15 is simulated.
[0029]
In this state, a pulse sound is emitted only from the left side speaker 13 and a sound reaching the
left ear 16L and a sound reaching the right ear 16R are independently collected by microphones,
as shown in FIG. Impulse response train aLL (t) in the space between the speaker 13 and the left
ear 16L as shown in (a) and impulse response train in the space between the speaker 13 and the
right ear 16R as shown in FIG. 4 (b) Measure aLR (t) respectively.
[0030]
Next, the impulse response sequence aLL (t) is subjected to Fourier transform to calculate a
frequency characteristic PaLL (hereinafter referred to as transfer function ALL) as shown in FIG.
5 (a).
Further, by frequency-transforming the impulse response sequence aLR (t), a frequency
characteristic PaLR (hereinafter referred to as transfer function ALR) as shown in FIG. 5B is
calculated.
[0031]
Furthermore, pulse sound is emitted only from the speaker 14 on the right side, and the sound
reaching the left ear 16L and the sound reaching the right ear 16R are respectively collected by
the microphone independently, as shown in FIG. ) In the space between the speaker 14 and the
left ear 16L, and the impulse response train aRR (in the space between the speaker 14 and the
right ear 16R as shown in FIG. 4D) measure each t).
[0032]
Then, the frequency response PaRL (hereinafter referred to as transfer function ARL) as shown in
FIG. 5C is calculated by subjecting the impulse response sequence aRL (t) to Fourier transform,
and the impulse response sequence aRR (t) is calculated. Is Fourier-transformed to calculate a
frequency characteristic PaRL (hereinafter referred to as transfer function ARR) as shown in FIG.
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[0033]
Next, the inverse matrix A-1 of a 2-row 2-by-2 regular matrix A having transfer functions ALL,
ALR, ARL and ARR as elements is determined, and each element of the inverse matrix A-1 is
calculated by the arithmetic circuit 17- The correction transfer functions H11, H12, H21 and
H22 are assumed to be twenty.
That is, each correction transfer function H11, H12, H21, H22 is calculated | required based on
the relationship of following Formula (1)-(5).
[0034]
Then, the correction transfer functions H11, H12, H21 and H22 are realized by IIR digital filters
and applied to the arithmetic circuits 17, 18, 19 and 20.
When the correction transfer functions H11, H12, H21, and H22 are set in this way, the impulse
responses of the arithmetic circuits 17 to 20 are as shown in FIGS. 6A to 6D, and furthermore,
each impulse response is subjected to Fourier transform 7 (a) to 7 (d) are transfer functions
(frequency characteristics) in the frequency domain.
[0035]
As described above, the correction circuit 10b is constructed, and stereo audio signals SL and SR
in which the head related transfer functions are superimposed on the left and right channels
supplied from the sound source apparatus when listening in an arbitrary sound field are The
following effects can be obtained by actually supplying the speakers 13 and 14 in the passenger
compartment 15 through the correction circuit 10b.
[0036]
In FIG. 1, the transfer function between the speaker 13 and the left ear 16L of the listener 16 in
the actual cabin 15 is BLL, the transfer function between the speaker 13 and the right ear 16R is
BLR, the speaker 14 and the left ear 16L. Assuming that the transfer function up to BRL, the
transfer function up to the speaker 14 and the right ear 16R are BRR, the sound reaching the left
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ear 16L of the listener 16 is PL, and the sound reaching the right ear 16R is PR. The determinant
of the following equation (6) holds true.
[0037]
Here, each of the corrected transfer functions H11, H12, H21 and H22 is a regular matrix having
transfer functions ALL, ALR, ARL and ARR as elements characterized by the sound field
characteristics shown in FIG. Since the setting is made based on the inverse matrix of A, when the
audio signals SL and SR are supplied to the correction circuit 10b, the sound field characteristics
in the passenger compartment 15 are canceled by the correction transfer functions H11, H12,
H21 and H22. It will be (corrected).
For this reason, the listener 16 can listen to a sound equivalent to the sound reproduced on the
basis of the audio signals SL and SR on which the head-related transfer function is superimposed
when the user listens in an arbitrary sound field.
As a result, the center sound image is localized to the front of the listener 16 and the listener 16
can listen with the spread of the symmetrical sound field.
[0038]
Further, as shown in FIGS. 4 (a) to 4 (d), impulse response trains aLL (t) to a RR of relatively
simple waveforms measured in the anechoic chamber 23 simulating the passenger compartment
15. Since the transfer functions H11 to H22 are constructed based on (t), the transfer for
correcting the sound field characteristic of the entire interior of the passenger compartment 15
by applying the head transfer function correction method described in the conventional example.
The correction circuit 10b can be formed by a simple IIR digital filter as compared to the case of
constructing a function.
Second Embodiment Next, a second embodiment will be described with reference to the
drawings.
Further, as a preferred embodiment, an on-vehicle audio device will be described.
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[0039]
The audio apparatus of this embodiment has the same configuration as the on-vehicle audio
apparatus 9 shown in FIG.
[0040]
However, the transfer functions H11 to H22 of the arithmetic circuits 17 to 20 of the correction
circuit 10b are set based on an algorithm different from that of the first embodiment, and are
designed by the method described below.
[0041]
First, as shown in FIG. 2, the dummy listener 16 and the left and right speakers 13 and 14 are
disposed in the anechoic chamber 23 in a state where the positional relationship in the
compartment 15 is simulated.
In this state, pulse sound is emitted only from the left speaker 13 disposed in the anechoic
chamber 23, and sounds reaching the left ear 16L and the right ear 16R of the dummy listener
16 are independently collected by the microphones. By doing this, the impulse response trains
aLL (t) and aLR (t) as shown in FIGS. 4 (a) and 4 (b) are respectively measured.
[0042]
Also, the pulse sound is emitted only from the right side speaker 14 disposed in the anechoic
chamber 23, and the sounds reaching the left ear 16L and the right ear 16R of the dummy
listener 16 are independently collected by microphones. By making a sound, the impulse
response trains aRL (t) and aRR (t) as shown in FIGS. 4 (c) and 4 (d) are respectively measured.
[0043]
Next, as shown in FIG. 3, the pulse sound is emitted only from the left speaker 13 disposed in the
actual compartment 15, and the sound reaching the left ear 16L and the right ear 16R of the
listener 16 is Each of the impulse response trains yLL (t) and yLR (t) is measured by collecting
sound independently with the microphones.
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[0044]
Also, pulse sound is emitted only from the right speaker 14 disposed in the actual cabin 15, and
sounds reaching the left ear 16L and the right ear 16R of the listener 16 are independently
collected by the microphones. Thus, each impulse response train yRL (t) and yRR (t) is measured.
[0045]
FIGS. 8 (a) to 8 (d) show the waveforms of the impulse response trains yLL (t), yLR (t), yRL (t),
yRR (t) thus measured.
[0046]
Next, as shown in FIGS. 9 (a) and 9 (b), the impulse response trains yLL (t) and aLL (t) are
compared, and as shown in FIGS. 10 (a) and 10 (b). The impulse response train yLL (t), based on
the envelope CV at ΔT, a period until the amplitude of the impulse response train aLL (t)
becomes substantially zero (ie, a period until the attenuation amplitude becomes substantially
zero, and so on). Modulate the amplitude of
That is, a portion common to the impulse response sequence aLL (t) in the impulse response
sequence yLL (t) is extracted, and amplitude modulation is performed based on the abovementioned envelope CV, as shown in FIG. Generate an impulse response sequence y'LL (t).
[0047]
Also for the other impulse response trains yLR (t), yRL (t), yRR (t), the amplitudes are similarly
calculated based on the impulse response trains aLR (t), aRL (t), aRR (t). By modulation, an
amplitude modulated impulse response train y′LR (t), y′RL (t), y′RR (t) is generated.
[0048]
That is, as shown in FIG. 10, y'LR (t) is modulated by modulating yLR (t) based on an envelope
within a period until aLR (t) becomes almost zero. To generate y′RL (t) by modulating yRL (t)
based on the envelope within a period until aRL (t) becomes approximately zero, and aRR (t)
approximately zero By modulating yRR (t) based on the envelope within the time period to
generate y'RR (t).
[0049]
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Next, transfer functions (frequency characteristics) are obtained by Fourier transforming each
impulse response sequence y'LL (t), y'LR (t), y'RL (t), y'RR (t). Calculate YLL, YLR, YRL, YRR.
[0050]
Next, as in the above equations (1) to (5), the inverse matrix Y-1 of a 2-row 2-by-2 regular matrix
Y having transfer functions YLL, YLR, YRL, YRR as elements is determined, and the inverse is
obtained. The elements of the matrix Y-1 are set to the transfer functions H11 to H22 of the
arithmetic circuits 17 to 20, respectively.
That is, the transfer function ALL in the above equation (1) is set as YLL, ALR as YLR, ALR as
YLR, and ARR as YRR, and transfer functions H11 to H22 are respectively set.
[0051]
Thus, the stereo audio signal in which each calculation circuit 17 to 20 of the correction circuit
10b is formed, and the head-related transfer function is superimposed on the left and right
signals supplied from the sound source when it is heard in an arbitrary sound field. When SL and
SR are supplied to the speakers 13 and 14 in the vehicle compartment 15 through the correction
circuit 10b, the characteristics of the transfer functions BLL to BRR in the vehicle compartment
15 are canceled out by the transfer functions H11 to H22 of the arithmetic circuit 10b
(correction Therefore, the listener 16 listens to the sound equivalent to the sound to be
reproduced based on the audio signals SL and SR on which the head related transfer function is
superimposed when the listener 16 listens in an arbitrary sound field. Is possible.
As a result, the center sound image is localized to the front of the listener 16 and the listener 16
can listen with the spread of the symmetrical sound field.
[0052]
Further, impulse responses measured in an actual cabin 15 based on envelopes of impulse
response trains aLL (t) to aRR (t) measured in an anechoic chamber 23 simulating the cabin 15
Amplitude-modulates the columns yLL (t) to yRR (t) and performs calculations based on the
transfer functions YLL to YRR obtained from the amplitude-modulated impulse response trains
y'LL (t) to y'RR (t) Since the transfer functions H11 to H22 of the circuits 17 to 20 are set, the
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correction circuit 10b can be constructed with a simple IIR digital filter.
[0053]
Furthermore, the transfer functions H11 to H22 include the characteristics of the impulse
response trains yLL (t) to yRR (t), that is, the characteristics characterized by the sound field
characteristics in the actual cabin 15. Therefore, the effects of the transfer functions BLL to BRR
in the vehicle interior 15 shown in FIG. 1 can be corrected effectively.
[0054]
In the second embodiment, as described above, the envelopes of the impulse response trains aLL
(t) to aRR (t) measured in the anechoic chamber 23 are used in the actual vehicle compartment
15. Although it was decided to amplitude modulate the measured impulse response trains yLL (t)
to yRR (t), the present invention is not limited to this.
[0055]
As indicated by the period ΔT in FIGS. 9 and 10, the impulse response trains aLL (t) to aRR (t)
have impulse response trains yLL (t) to yRR (t) within a period until they become almost zero.
The transfer functions H11 to H22 may be set based on the transfer functions YLL to YRR
obtained from the impulse response series yLL (t) to yRR (t) by extracting t) as it is.
That is, the impulse response trains yLL (t) to yRR (t) measured in the actual compartment 15 are
obtained by the envelopes of the impulse response trains aLL (t) to aRR (t) measured in the
anechoic chamber 23. Amplitude modulation may not be performed.
[0056]
However, in consideration of the occurrence of high frequency noise etc., impulse response trains
yLL (t) to yRR measured in the actual cabin 15 by the envelopes of the impulse response trains
aLL (t) to aRR (t). It is desirable to amplitude modulate (t).
[0057]
Also, the first and second embodiments are shown for easy understanding of the present
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invention, and the present invention is not limited to these embodiments.
In particular, although the case where the correction circuit 10b includes the four arithmetic
circuits 17 to 20 and the addition circuits 21 and 22 has been described, these circuits may be
realized by one digital filter.
The configuration appropriately changed in accordance with the design specification and the like
is included in the present invention.
Third Embodiment Next, an audio device according to a third embodiment will be described with
reference to FIGS.
In FIGS. 11 to 16, parts that are the same as or correspond to those in FIG. 1 are denoted by the
same reference numerals.
Further, the present embodiment is an audio apparatus suitable for use in a room (for example, a
living room or the like) 200 such as a house.
[0058]
In FIG. 11, in the present audio apparatus, the audio apparatus main body 100 disposed in the
room 200 as a reproduction sound field, the speakers 101L and 101R of the left channel and the
right channel, and the listener 16 perform remote control. The remote controller 102 is
configured.
[0059]
The audio apparatus main unit 100 is a unit capable of selectively combining a CD reproducing
apparatus and an MD reproducing apparatus for reproducing a recording medium such as a CD
or MD in which an audio source is recorded according to the preference of the listener. It has an
integral structure in which the molds and their reproduction devices are incorporated in one
casing in advance.
[0060]
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Further, as shown in the block diagram of FIG. 12, the audio apparatus main body 100 is
supplied with audio input signals Lin and Rin of the left and right channels reproduced by the
reproducing apparatus 300 such as the CD reproducing apparatus and the MD reproducing
apparatus. The head related transfer function circuit 10a, the correction circuit 10b, and the
output amplifiers 11 and 12 are provided.
Furthermore, a control unit 103 including a microprocessor (MPU), a storage unit 104 formed of
a rewritable non-volatile semiconductor memory or the like, and a light detection unit 105 are
provided.
[0061]
Here, head transfer function circuit 10a, correction circuit 10b, and output amplifiers 11, 12
have the same configuration as head transfer function circuit 10a, correction circuit 10b, and
output amplifiers 11, 12 shown in FIG. Audio signals L and R are generated by correcting the
audio input signals Lin and Rin, and are supplied to the left and right speakers 101L and 101R.
[0062]
The storage unit 104 stores data for setting the transfer functions H11, H12, H21, and H22 of
the correction circuit 10b described in the first and second embodiments.
[0063]
However, not only data of one type of transfer function corresponding to one listening position is
stored in storage unit 104, but as shown in FIG. 14, a plurality of listening positions W, X, Y are
stored. , Data of plural types of transfer functions corresponding to {A11, aa12, aa21, aa22},
{bb11, bb12, bb21, bb22}, {cc11, cc12, cc21, cc22}, {dd11, dd12, dd21, dd22 } Is stored.
[0064]
Although FIG. 14 shows data of four types of transfer functions corresponding to four listening
positions W, X, Y and Z as an example, the present invention is not limited to this, and any data
may be used. It is possible to store a number of listening positions and data of any kind of
corresponding transfer function.
[0065]
The light detection unit 105 includes a photoelectric conversion element for receiving the light
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signal from the remote controller 102 and converting it into an electric signal, and supplies the
electric signal to the control unit 103.
[0066]
The control unit 103 detects code data indicating a listening position included in the electric
signal from the light detection unit 105, and the above transfer function stored in the storage
unit 104 based on the detected code data. Data of the memory are accessed to the memory and
supplied to the correction circuit 10b.
[0067]
That is, when the listener operates a predetermined operation button switch provided on the
remote controller 102, an optical signal including code data of a specific listening position
corresponding to the operation button switch is emitted from the remote controller 102. Be
The light detection unit 105 receives the light signal, converts it into an electric signal, and
supplies the electric signal to the control unit 103.
Then, the control unit 103 performs memory access to the storage unit 104 based on the code
data, and supplies the data of the transfer function corresponding to the code data from the
storage unit 104 to the correction circuit 10b, whereby the transfer function of the correction
circuit 10b Is updated to the transfer function instructed by the listener.
[0068]
FIG. 13 is a plan view showing the appearance of the remote controller 102. As shown in FIG.
In the figure, the remote controller 102 is provided with a plurality of function keys F1 to F3 and
a ten key 106 identified by a numeral, and these keys F1 to F3 and 106 serve as the operation
button switches described above. ing.
Further, at the tip of the remote controller 102, a light emitting unit 107 provided with an
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infrared light emitting element that emits the above-mentioned light signal is provided.
[0069]
Although not shown, a unique key corresponding to the detected key is detected inside the
housing of the remote controller 102, among the function keys F1 to F3 and the ten keys 106. A
decoder circuit is provided which generates code data of the listening position.
In addition, a modulation circuit is provided which modulates the code data of the unique
listening position output from the decoder circuit and supplies the modulated data to the light
emitting unit 107.
Furthermore, a drive circuit is provided which causes the light emitting unit 107 to emit an
optical signal including unique code data by power-amplifying the output of the modulation
circuit and supplying the output to the infrared light emitting element.
[0070]
Here, as shown in FIG. 15, the above-mentioned decoder circuit generates code data of listening
positions W, X, Y, Z corresponding to the ten keys 106.
[0071]
That is, when one of the ten keys 106 is pressed after the function key F1 is pressed, code data
indicating the listening position W is generated, and any one of the ten keys 106 is generated.
When any key is pressed, code data indicating the listening position X is generated, and when
any key of the ten keys 106 is pressed, code data indicating the listening position Y is generated [
When the *] key is pressed, code data indicating a listening position Z is generated.
[0072]
The correspondence between the ten keys 106 and the listening position is merely shown as an
example, and it is possible to set other correspondences.
[0073]
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Also, although the function key F1 is provided for so-called mode switching for updating the
transfer function of the correction circuit 10b, the other function key F2 designates a CD
reproducing device of the reproducing device 300. The function key F3 is provided to control the
operation of the MD reproducing apparatus of the reproducing apparatus 300.
For example, if the listener presses the function key F2 and then presses the key on the ten key
106, the music of the first track recorded on the CD, which is a recording medium, can be
designated and reproduced. .
[0074]
Next, a method of generating transfer function data stored in storage unit 104 shown in FIG. 14
will be described.
[0075]
The left and right speakers are arranged in an anechoic chamber imitating the room 200 as a
reproduction sound field, and the microphones are arranged on both ears of the dummy listener.
Then, the dummy listener is positioned at the listening position in the anechoic chamber
corresponding to the listening position W of the room 200, and the pulse sound emitted from the
left and right speakers is measured by the microphone, thereby the first and second
embodiments. The impulse response sequence described in the example is determined, and based
on this impulse response sequence, data {aa11, aa12, aa21, aa22} of the transfer function
corresponding to the listening position W is generated.
Similarly, the transfer function data {bb11, bb12, bb21, bb22} when the dummy listener is
positioned at the listening position in the anechoic chamber corresponding to the listening
position X of the room 200, Transfer function data {cc11, cc12, cc21, cc22} when the dummy
listener is positioned at the listening position in the anechoic chamber corresponding to the
listening position Y, and the anechoic chamber corresponding to the listening position Z in the
room 200 Similarly, transfer function data {dd11, dd12, dd21, dd22} when the dummy listener is
located at the listening position is generated in the same manner.
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[0076]
Then, the generated transfer function data is stored in the storage unit 104 in association with
the ten key 106 and the function key F1 of the remote controller 102.
The data of the transfer function is stored in the storage unit 104 when the audio device is
shipped, or distributed to the listener as a semiconductor memory storing the data of the transfer
function after the product is shipped. It is possible to replace it.
[0077]
Next, the operation of the present audio apparatus when the listener operates the remote
controller 102 in the actual room 200 will be described.
[0078]
For example, after the listener 16 moves to the listening position Y in the room 200 and presses
the function key F1 of the remote controller 102, pressing the key of the ten keys 106 causes the
code of the listening position Y to A light signal including data is emitted from the light emitting
unit 107.
The light detection unit 105 receives the light signal, and the control unit 104 causes the storage
unit 104 to supply the transfer function data {cc11, cc12, cc21, cc22} corresponding to the
listening position Y to the correction circuit 10b.
Thereby, the transfer function of the correction circuit 10b is updated by the data {cc11, cc12,
cc21, cc22}.
[0079]
When the transfer function of the correction circuit 10b is updated in this way, as schematically
shown in FIG. 11, in the sound field space from the speaker 101L of the left channel to the left
and right ears 16L, 16R of the listener 16 at the listening position Y. The sound image is a
listener 16 by correcting the effects of the transfer functions BLL and BLR and the transfer
functions BRL and BRR of the sound field space from the right channel speaker 101R to the left
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and right ears 16L and 16R of the listener 16 at the listening position Y. It is possible to provide
a natural reproduced sound with a sense of expansion by being localized in front of the.
[0080]
When the listener 16 moves to the listening position X and presses the key of the remote
controller 102, the transfer function of the correction circuit 10b is updated by the data {bb11,
bb12, bb21, bb22} and the sound image is displayed. The sound can be localized in front of the
listener 16 at the listening position X to provide a natural reproduced sound.
Further, when the listener 16 moves to the listening position W and presses the key of the
remote controller 102, for example, the sound image is localized in front of the listener 16 at the
listening position W to provide natural reproduced sound. When the listener 16 moves to the
listening position Z and presses the [*] key of the remote control 102, the sound image is
localized in front of the listener 16 at the listening position Z to provide natural reproduced
sound. It is possible to
[0081]
As described above, according to the present embodiment, data of the transfer function
corresponding to the listening position defined in the room 200 as the reproduction sound field
space is stored, and the listener changes the listening position. Accordingly, since the transfer
function of the correction circuit 10b is updated, the listener 16 can listen to the reproduced
sound having a symmetrical sound field spread even if the listening position is moved.
[0082]
In the third embodiment described above, the listener 16 designates the listening position to the
audio apparatus main body 100 by operating the ten keys 106 of the remote controller 102, but
the others The configuration of
For example, it may be configured as shown in FIG. 16 as a modification.
[0083]
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In FIG. 16, the light detection portion 105 is provided with two photoelectric conversion
elements 105a and 105b spaced apart at a predetermined distance, and the listener 16 operates
the remote controller 102 at an arbitrary position. When the infrared light is emitted from the
light emitting unit 107, the photoelectric conversion elements 105a and 105b receive the
emitted infrared light.
Then, the control unit 103 geometrically calculates the positional relationship between the light
emitting unit 107 and the photoelectric conversion elements 105a and 105b based on the two
light reception results from the photoelectric conversion elements 105a and 105b. Determine the
current position (listening position).
Then, data of the transfer function corresponding to the determined listening position is read out
from the storage unit 104 shown in FIG. 4, and the transfer function of the correction circuit 10b
is updated.
[0084]
According to such a configuration, the listener 16 does not need to operate the ten keys 106 of
the remote controller 102.
Therefore, if the function key F1 of the remote controller 102 is assigned for emitting infrared
light, the listener 16 can easily notify the audio device main body 100 of the listening position
simply by pressing the function key F1. As a result, convenience can be improved.
[0085]
Further, the photoelectric conversion elements 105a and 105b for receiving the light from the
remote controller 102 may be attached to one end of each of the left and right speakers 101L
and 101R instead of being provided in the audio apparatus main body 100.
[0086]
Although the audio apparatus provided in the room 200 such as a house has been described in
the third embodiment, the present audio apparatus can be applied to an on-vehicle audio
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apparatus or the like.
[0087]
As described above, according to the audio apparatus of the present invention, a correction
circuit (an arithmetic circuit having a transfer function characterized by the sound field
characteristics of the space between the speakers of both channels and the listener) ) Precorrects the input audio signals of both channels and supplies the corrected audio signals to the
speakers of both channels. It becomes possible to listen to the sound equivalent to the sound to
be reproduced based on the input audio signal on which is superimposed, and the center sound
image is localized in front of the listener, and the listener has a symmetrical sound field spread.
You can listen to it.
[0088]
Also, when the listening position of the listener changes, the position detection means sets the
correction transfer function according to the changed listening position, so that the listener is
made aware of the listening position. Instead, it is possible to provide a reproduced sound with a
symmetrical sense of spread.
[0089]
Brief description of the drawings
[0090]
1 is a block diagram showing the configuration of a car audio system according to the present
embodiment.
[0091]
2 is an explanatory diagram for explaining a method for setting the transfer function of the
arithmetic circuit.
[0092]
3 is an explanatory diagram for further explaining the method for setting the transfer function of
the arithmetic circuit.
[0093]
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4 is a waveform diagram showing an example of an impulse response sequence measured in an
anechoic chamber, with the vertical axis as amplitude and the horizontal axis as time.
[0094]
5 is a characteristic diagram showing the frequency characteristics of the impulse response
series of FIG. 4 with the vertical axis representing power and the horizontal axis representing
frequency.
[0095]
6 is a waveform diagram showing the impulse response characteristics of each arithmetic circuit
of the first embodiment, the vertical axis as the amplitude, the horizontal axis as time.
[0096]
7 is a characteristic diagram showing the frequency characteristics of the impulse response train
of FIG. 6, with the vertical axis representing power and the horizontal axis representing
frequency.
[0097]
FIG. 8 is a waveform diagram showing an example of an impulse response train measured in a
vehicle compartment, with the vertical axis as amplitude and the horizontal axis as time.
[0098]
9 is a waveform diagram showing enlarged one of the impulse response series of FIG. 8 and FIG.
[0099]
10 is a waveform diagram for explaining the setting method of the arithmetic circuit in the
second embodiment.
[0100]
<Figure 11> It is the block diagram which shows the constitution of the audio device of 3rd
execution form.
[0101]
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12 is a block diagram showing the configuration of the audio device body in FIG.
[0102]
13 is a plan view showing the external shape of the remote controller.
[0103]
14 is an explanatory diagram for explaining the function of the remote controller.
[0104]
15 is an explanatory view schematically showing data of the transfer function stored in the
storage unit.
[0105]
<Figure 16> It is the block diagram which shows the constitution of the deformation example of
the audio device itself in 3rd execution form.
[0106]
FIG. 17 is an explanatory view for explaining problems of the prior art.
[0107]
Explanation of sign
[0108]
9: Audio device 10a: Head transfer function circuit 10b: Correction circuit 13, 100L: Left channel
speaker 14, 101R: Right channel speaker 15: Cabin 16: Listener 16L: Left ear 16R: Right ear 1720 ... Arithmetic circuit 21, 22 ... Addition circuit 23 ... Anechoic chamber 100 ... Audio device
body 102 ... Reproduction device 103 ... Control unit 104 ... Storage unit 105 ... Photodetection
unit 105a, 105b ... Photoelectric conversion element
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