I: ATTENUATOR A ,DFL
US 20010016045A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2001/0016045 A1
Ohta
(43) Pub. Date:
(54) METHOD OF CORRECTING SOUND FIELD
(57)
Aug. 23, 2001
ABSTRACT
IN AN AUDIO SYSTEM
(76) Inventor
Yoshiki Ohta Saitama (JP)
i
In correcting the sound ?eld, the loudspeakers 6FL to 6WF are
’
sounded by the noise. The attenuation factors of the inter
Correspondence Address;
SUGHRUE, MION, ZINN, MACPEAK &
band attenuators ATF11 to ATFki for adjusting gains of the
band-pass ?lters BPF11 to BPFki to the frequency in respec
SEAS, PLLC
tive channels are corrected based on detection results of the
2100 Pennsylvania Avenue, NW.
Washington, DC 20037-3202 (US)
reproduced sounds of the loudspeakers 6FL to 6WF. Then, the
attenuation factors of the channel-to-channel attenuators
_
ATG1 to AT G5 are corrected based on the detection results of
(21) Appl' NO"
09/781,274
the reproduced sounds of the loudspeakers 6FL to 6WF. Then,
(22) Filed;
Feb 13, 2001
the delay times of the delay circuits DLY1 to DLY5 are
corrected based on the detection results of the reproduced
(30)
Foreign Application PI‘iOI‘itY Data
Feb. 14, 2000
sounds of the loudspeakers 6FL to 6WF. Then, the attenuation
factor of the channel-to-channel attenuator ATGk is cor
meted based Onthe detection resultofthe reproduced Sound
(JP) ................................. .. P.2000-035034
Publication Classi?cation
of the loudspeaker 6WF as the subWoofer, Whereby the levels
of the reproduced sounds reproduced by the loudspeakers
(51)
(52)
Int. Cl.7 ............................. .. H03G 5/00; H04B 3/20
US. Cl. ............. .. 381/98; 381/66; 381/97; 381/943
6FL t0 6WF are adjusted to be made ?at over the audio
frequency band.
2
ATF11
m
ATTENUATOR
I: ATTENUATOR A
5
SF12
,DFL
ATP‘?
ATTENUATOR
L """"
SW21 "
M
SFH
/
S R t /:
F
SW22
'
i
53%
_ _ _ _ _ __
:“BPF21- LJATFm~
=__B_F:EA___E
LéIFzlul
ADDZ
o
SF21 ~ SF21
AWENUATOR
8G2
a , , _ . .
, _ . .
DLY2
ATG2
DELAY +DFR
CIRCUIT
SDL2
I
_ . .
_ _ _ d
_ .......................................................... ._
SW3‘
’
H/
r ______ n
Sc
ADDS
r _____ “'
BPF31~ i,
'ATFa1~ ‘A
SW32
LFEEEBLJ TLAIFLF
_SW“‘
SF31 ~ SFsi J
=
=
SWF
E“
/
ma
5
!
m
0
ATF12
5
ATTENUATOR
563
ATTENUATOR
SM
ATFK
ATTENUATOR
LO“
DLYs
I
.
l
AY
ATTENUATOR
SF“
_
ATGs
9
CIRCUIT
+Dc
Arm SDLa
LT‘ um I
Patent Application Publication Aug. 23, 2001 Sheet 4 0f 11
US 2001/0016045 A1
1.4
15a
15d
MIDDLE/HIGH FREQUENCY
DM
PMH
/
BAND PROCESSING PORTION
(EXCEPT SUBWOOFER)
15b
LOW FREQUENCY
PL
BAND PROCESSING PORTION i> cAgggEfgglNe ~—> SGk
(EXCEPT SUBWOOFER)
15c
SUBWOOFER LOW FREQUENCY
BAND PROCESSING PORTION
PWFL
>
(ONLY SUBWOOFER)
1\ LOW FREQUENCY BAND_L
MIDDLE/HIGH FREQUENCY BAND
_
(GAdIBN)
V
0'2
LOGARITHMIC FREQUENCY (kHz)
Patent Application Publication Aug. 23, 2001 Sheet 5 0f 11
“
US 2001/0016045 A1
TOTAL POWER OF
LOUDSPEAKERS 6FL TO 6WF
J/
_ -------------- --\__
P(OdWEBR)
POWER OF
LOUDSPEAKERS 6FL TO 6BR
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _Z_ lri:L'IL'IL':II'J:;':;':;.‘:I:I:L'=_l
: l
': \.
POWER OF LOUDSPEAKER 6WF
'1
1i
E\
hxq
LOW FREQUENCY BAND
v
LOGARITHMIC FREQUENCY (KHZ)
Patent Application Publication Aug. 23, 2001 Sheet 7 0f 11
US 2001/0016045 A1
FIG. 8
@
FREQUENCY CHARACTERISTIC "V810
CORRECTING PROCESS
T
CHANNEL-TO-CHANNEL LEVEL
CORRECTING PROCESS
“v S20
T
PHASE CHARACTERISTIC
CORRECTING PROCESS
S30
T
FLATNESS CORRECTING PROCESS
@
"M S40
Patent Application Publication Aug. 23, 2001 Sheet 8 0f 11
US 2001/0016045 A1
FIG. 9
@3
INITIALIZE THE ATTENUATORS
1
Y
MEASURE THE SOUND
FIELD CHARACTERISTIC
1
SET A TARGET CURVE
~S108
CALCULATE ADJUSTED
3114'»
VALUES Fn (X, J)
"M8110
NORMALIZING PROCESS M8120
S122
NO
YES
CALCULATE THE ATTENUATION FACTORS
SFxj, ADJUST THE ATTENUATION FACTORS ~S126
OF THE INTER-BAND ATTENUATORS
@
Patent Application Publication Aug. 23, 2001 Sheet 9 0f 11
US 2001/0016045 A1
FIG. 10
@
INITIALIZE THE ATTEN UATORS
N S200
T
x+1
MEASURE THE SO UND
FIELD CHARACTERISTIC
~s204
i
~ S206
S208
HAVE
PROCESSES OF THE CHANNELS
1 TO 5 BEEN COMPLETED
SET TARGET DATA “S210
T
CALCULATE ADJUSTED VALUES OF THE
CHANNEL-TO-CHANNEL ATTENUATORS ~S212
Y
ADJUST THE CHANNEL-TO-CHANNEL
ATTENUATORS
@
Patent Application Publication Aug. 23, 2001 Sheet 10 0f 11
US 2001/0016045 A1
FIG. 1 1
@@
INITIALIZATION ~ S300
i
AV
MEASURE THE SOUND
N 8304
FIELD CHARACTERISTIC
1
HAVE
PROCESSES OF ALL
S308
CHANNELS BEEN COMPLETED
x = k?
CALCULATE DELAY TIMES
N S310
1
AVG <— AVG +1 “S312
NO
S314
AVG = AVERAGE?
YES I
CALCULATE THE AVERAGE DELAY TIME
"\1 S316
1
ADJUST THE DELAY CIRCUITS N S318
@
Patent Application Publication Aug. 23, 2001 Sheet 11 0f 11
US 2001/0016045 A1
SET PARAMETERS ~ $400
SET TARGET DATA "V S402
INITIALIZE THE ATTENUATOR
TV $404
ON THE SUBWOOFER CHANNEL
T
MEASURE THE SOUND FIELD CHARACTERISTIC
(MIDDLE/HIGH FREQUENCY BAND OF 5 CHANNELS)
N S406
I
MEASURE THE SOUND FIELD CHARACTERISTIC
(LOW FREQUENCY BAND)
i
MEASURE THE SOUND FIELD CHARACTERISTIC
(ONLY SUBWOOFER)
l
CALCULATE THE ATTENUATOR ADJUSTED
VALUE ON THE SUBWOOFER CHANNEL
i
ADJUST THE ATTENUATOR ON
THE SUBWOOFER CHANNEL
@
\' S408
Aug. 23, 2001
US 2001/0016045 A1
METHOD OF CORRECTING SOUND FIELD IN AN
AUDIO SYSTEM
BACKGROUND OF THE INVENTION
[0001]
1. Field of the Invention
the sound ?eld space, the impulse signal is directly supplied
to the loudspeakers. Therefore, there is such a subject that
the phase characteristic of the overall audio system cannot
be corrected into the phase characteristic that can produce
the proper sound ?eld space.
[0011] Also, upon correcting the frequency characteristic
[0002] The present invention relates to a sound ?eld
correcting method of correcting a sound ?eld characteristic
in an audio system.
of the sound ?eld space, a method of analyZing the fre
[0003] 2. Description of the Related Art
feeding back the analyZed results to the equaliZer is
[0004]
The audio system is required to produce a sound
quency characteristics of the reproduced sounds of the pink
noise by using a group of narroW-band ?lters and then
employed.
In this audio system in the prior art, an equaliZer for
[0012] HoWever, in case the frequency characteristics of
measured signals derived from the reproduced sounds of the
pink noise being reproduced via the loudspeakers are fre
quency-analyZed by individual narroW-band ?lters in a
group of narroW-band ?lters, the analyZed result suitable for
the frequency characteristic of the equaliZer cannot be
adjusting frequency characteristics of the input audio signals
and delay circuits for delaying the audio signals output from
subject that, if the frequency characteristic of the equaliZer
?eld space that can give a presence. In the prior art, the
sound ?eld correcting method of the audio system disclosed
in Utility Model Application Publication (KOKAI) Hei
6-13292 has been knoWn.
[0005]
the equaliZer are provided, and then outputs of the delay
circuits are supplied to loudspeakers.
[0006] Also, in order to correct the sound ?eld character
istic, there are provided a pink noise generator, an impulse
generator, a selector circuit, a microphone used to measure
the reproduced sounds being reproduced by the loudspeak
obtained With good precision. As a result, there is such a
is feedback-controlled based on the analyZed result, it
becomes difficult to correct properly the frequency charac
teristic of the sound ?eld space.
SUMMARY OF THE INVENTION
ers, a frequency analyZing means, and a delay time calcu
[0013] It is an object of the present invention to overcome
the above subjects in the prior art and provide a sound ?eld
lating rneans. Then, a pink noise generated by the pink noise
generator is supplied to the equaliZer via the selector circuit,
correcting rnethod capable of implementing a higher quality
and an impulse signal generated by the impulse generator is
directly supplied to the loudspeakers via the selector circuit.
sound ?eld space.
[0014] A sound ?eld correcting method of the present
invention in an audio system Which includes a plurality of
[0007] Upon correcting the phase characteristic of the
sound ?eld space, propagation delay times of the impulse
sounds from the loudspeakers to a listening position are
measured by measuring the impulse sound reproduced via
the loudspeakers by using the microphone While supplying
directly the impulse signal from the above irnpulse generator
to the loudspeakers, and then analyZing the measured signals
by using the delay time calculating means.
[0008] In other Words, the propagation delay times of
respective irnpulse sounds are measured by directly supply
ing the impulse signal to the loudspeakers and calculating
tirne differences from points of time When respective
irnpulse signals are supplied to respective loudspeakers to
points of time When respective irnpulse sounds being repro
duced by every loudspeaker come up to the microphone by
using the delay time calculating means. Thus, the phase
characteristic of the sound ?eld space can be corrected by
adjusting the delay times of the delay circuits based on the
measured propagation delay times.
[0009] Also, upon correcting the frequency characteristic
of the sound ?eld space, the pink noise is supplied from the
pink noise generator to the equaliZer and then the repro
duced sounds of the pink noise being reproduced via the
loudspeakers are measured by the microphone, and then
frequency characteristics of these rneasured signals are
analyZed by the frequency analyZing rneans. Thus, the
frequency characteristic of the sound ?eld space can be
corrected by feedback-controlling the frequency character
istic of the equaliZer based on the analyZed results.
[0010] HoWever, in the audio system in the prior art, as
described above, upon correcting the phase characteristic of
variable gain type frequency discrirninating means for dis
crirninating input audio signals into a plurality of frequen
cies, and delaying means for adjusting delay times of the
audio signals that are frequency-discrirninated by the fre
quency discrirninating means, whereby the audio signals are
supplied to sound generating means via the variable gain
type frequency discrirninating means and the delaying
means, the correcting method comprising a ?rst step of
supplying a noise to the sound generating means via the
variable gain type frequency discrirninating means and the
delaying means, and then detecting reproduced sounds gen
erated by the sound generating means; a second step of
analyZing frequency characteristics of the reproduced
sounds based on detection results detected by the ?rst step
in ansWer to the variable gain type frequency discrirninating
means; a third step of supplying the noise to the sound
generating means via the plurality of variable gain type
frequency discrirninating means and the delaying means,
and then detecting the reproduced sounds generated by the
sound generating means; a fourth step of analyZing delay
characteristics of the reproduced sounds based on the detec
tion results detected by the third step; and a ?fth step of
adjusting frequency characteristics of the variable gain type
frequency discrirninating rneans based on the frequency
characteristics obtained by the second step, and adjusting
delay times of the delaying rneans based on the delay
characteristics obtained by the fourth step.
[0015] Also, a sound ?eld correcting method of the
present invention in an audio system Which supplies a
plurality of input audio signals to a plurality of sound
generating means via a plurality of signal transmission lines,
each of the signal transmission lines including a plurality of
Aug. 23, 2001
US 2001/0016045 A1
variable gain type frequency discriminating means for dis
criminating input audio signals into a plurality of frequen
cies, channel-to-channel level adjusting means for adjusting
levels of the audio signals, and delaying means for adjusting
delay times of the audio signals that are frequency-discrimi
nated by the variable gain type frequency discriminating
means, Whereby the audio signals are supplied to sound
generating means via the variable gain type frequency
discriminating means, the channel-to-channel level adjust
ing means, and the delaying means, the correcting method
BRIEF DESCRIPTION OF THE DRAWINGS
[0018]
FIG. 1 is a block diagram shoWing a con?guration
of an audio system including an automatic sound ?eld
correcting system according to the present embodiment;
[0019] FIG. 2 is a block diagram shoWing a con?guration
of the automatic sound ?eld correcting system;
[0020] FIG. 3 is a block diagram shoWing a pertinent
con?guration of the automatic sound ?eld correcting system;
signal transmission lines via the variable gain type fre
[0021] FIG. 4 is a block diagram shoWing another perti
nent con?guration of the automatic sound ?eld correcting
quency discriminating means, the channel-to-channel level
system;
adjusting means, and the delaying means, then detecting
reproduced sounds generated by the sound generating means
[0022] FIG. 5 is a vieW shoWing a frequency character
istic of a band-pass ?lter;
comprising a ?rst step of supplying a noise to respective
via respective signal transmission lines, and then analyZing
frequency characteristics of the reproduced sounds via
respective signal transmission lines based on detection
results in ansWer to the variable gain type frequency dis
criminating means; a second step of adjusting frequency
characteristics of the variable gain type frequency discrimi
[0023]
FIG. 6 is a vieW shoWing the problem in a loW
frequency band of a reproduced sound;
[0024] FIG. 7 is a vieW shoWing an eXample of arrange
ment of loudspeakers;
nating means on respective signal transmission lines based
on the frequency characteristics obtained by the ?rst step; a
third step of supplying the noise to respective signal trans
[0025]
mission lines via the variable gain type frequency discrimi
nating means, the channel-to-channel level adjusting means,
and the delaying means, then detecting the reproduced
sounds generated by the sound generating means via respec
acteristic correcting process;
tive signal transmission lines, and then analyZing delay
characteristics of the reproduced sounds via respective sig
nal transmission lines based on detection results; a fourth
step of adjusting delay times of the delaying means on
respective signal transmission lines based on the delay
characteristics obtained by the third step; a ?fth step of
[0026]
[0027]
the channel-to-channel level adjusting means, and the delay
by the sound generating means via respective signal trans
mission lines, and then analyZing levels of the reproduced
sounds via respective signal transmission lines based on
detection results; and a siXth step of adjusting the channel
to-channel level adjusting means based on analyZed results
of the levels of the reproduced sounds obtained by the ?fth
step via respective signal transmission lines.
[0016]
In addition, in the siXth step, an adjusted amount of
FIG. 9 is a ?oWchart shoWing a frequency char
FIG. 10 is a ?oWchart shoWing a channel-to
channel level correcting process;
[0028] FIG. 11 is a ?owchart showing a delay character
istic correcting process; and
[0029]
FIG. 12 is a ?oWchart shoWing a ?atness correct
ing process.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENTS
supplying the noise to respective signal transmission lines
via the variable gain type frequency discriminating means,
ing means, then detecting the reproduced sounds generated
FIG. 8 is a ?oWchart shoWing an operation of the
automatic sound ?eld correcting system;
[0030] An automatic sound ?eld correcting system, to
Which a sound ?eld correcting method according to an
embodiment of the present invention is applied, Will be
explained With reference to the accompanying draWings
hereinafter. FIG. 1 is a block diagram shoWing a con?gu
ration of an audio system including the automatic sound
?eld correcting system to Which the sound ?eld correcting
method according to the present embodiment is applied.
FIG. 2 to FIG. 4 are block diagrams shoWing the con?gu
ration of the automatic sound ?eld correcting system.
the plurality of channel-to-channel level adjusting means are
corrected such that a spectrum average level of the repro
digital audio signals SFL, SFR, Sc, SRL, SRR, SWF are
duced sounds reproduced by the plurality of sound gener
supplied from a sound source 1 such as a CD (Compact
ating means are made ?at over all audio frequency bands.
Disk) player, a DVD (Digital Video Disk or Digital Versatile
Disk) player, etc. via a signal transmission line having a
plurality of channels, and a noise generator 3 are provided
to the present audio system.
[0017] According to such sound ?eld correcting method,
since the correction of the sound ?eld can be carried out
under the same condition as the reproduction of the audio
sound, such correction of the sound ?eld can be imple
mented While totally taking account of the characteristic of
the overall audio system and the characteristic of the sound
?eld environment. Also, the reproduced sound, that is offen
sive to the ear, generated because the level of the reproduced
sound at a certain frequency in the audio frequency band is
enhanced or Weakened can be prevented, and also the sound
?eld space With the presence can be implemented.
[0031]
In FIG. 1, a signal processing circuit 2 to Which
[0032] Also, D/A converters 4FL, 4FR, 4c, 4RL, 4RR, 4WF
for converting digital outputs DFL, DFR, Dc, DRL, DWF
Which are signal-processed by the signal processing circuit
2 into analog signals, and ampli?ers SFL, SFR, 5c, SRL, SRR,
SWF for amplifying respective analog audio signals being
output from these D/A converters are provided. Respective
analog audio signals SPFL, SPFR, SPC, SPRL, SPRR, SPWF
ampli?ed by these ampli?ers are supplied to loudspeakers
Aug. 23, 2001
US 2001/0016045 A1
SFL, SFR, 5c, SRL, SRR, SWF on a plurality of channels
signal DN from the noise generator 3. Also, the sWitch
arranged in a listening room 7, etc., as shoWn in FIG. 7, to
sound them.
element SW11 is connected to the noise generator 3 via a
sWitch element SWN.
[0033] In addition, a microphone 8 for collecting repro
[0039]
duced sounds at a listening position RV, an ampli?er 9 for
trolled by a system controller MPU that consists of a
amplifying a sound collecting signal SM output from the
microprocessor described later. At the time of reproducing
the audio sound, the sWitch element SW12 is turned ON
(conductive) and the sWitch elements SW11, SWN are turned
OFF (nonconductive). At the time of correcting the sound
?eld, the sWitch element SW12 is turned OFF and the sWitch
elements SW11, SWN are turned ON.
microphone 8, and an A/D converter 10 for converting an
output of the ampli?er 9 into digital sound collecting data
DM to supply to the signal processing circuit 2 are provided.
[0034] Then, the present audio system provides a sound
?eld space With a presence to the listener at the listening
The sWitch elements SW11, SW12, SWN are con
to reproduce, and a loW frequency band exclusively repro
[0040] Band-pass ?lters BPF11 to BPFlj are connected in
parallel to output contacts of the sWitch elements SW11,
SW12 as frequency discriminating means, and thus the fre
quency dividing means that divides the frequency of the
ducing loudspeaker 6WF that has a frequency characteristic
to reproduce only the so-called heavy and loW sound.
BPF11 to BPFlj.
position RV by sounding all frequency band type loudspeak
ers 6FL, 6FR, 6c, 6R1“, 6RR each has a frequency characteristic
that enables an almost full range of the audio frequency band
input signal is constructed by the overall band-pass ?lters
the listener arranges the front loudspeakers (front left-side
[0041] In this case, suf?xes 11 to 1j attached to BPF11 to
BPFlj denote the order of center frequencies f1 to fj of the
loudspeaker, front right-side loudspeaker) 6FL, 6FR on tWo
band-pass ?lters BPF11 to BPFlj on the ?rst channel (x=1).
right and left channels and the center loudspeaker 6c in front
of the listening position RV, arranged the rear loudspeakers
band attenuator are connected to output contacts betWeen the
[0035]
For example, as shoWn in FIG. 7, in the case that
(rear left-side loudspeaker, rear right-side loudspeaker) 6R1],
6RR on tWo right and left channels at the rear of the listening
position RV, and arranges the loW frequency band exclu
sively reproducing subWoofer 6WF at any position according
to his or her taste, the automatic sound ?eld correcting
system installed in the present audio system can implement
the sound ?eld space With the presence by sounding six
loudspeakers 6FL, 6FR, 6c, 6R1], 6RR, 6WF by supplying the
analog audio signals SPFL, SPFR, SPC, SPRL, SPRR, SPWF,
Whose frequency characteristic and phase characteristic are
corrected, to these loudspeakers.
[0036] The signal processing circuit 2 is composed of a
digital signal processor (DSP), or the like. The automatic
sound ?eld correcting system consists of the digital signal
processor (DSP), etc., that cooperate With the noise genera
tor 3, the ampli?er 9, and the A/D converter 10 to execute
the sound ?eld correction.
[0037] More particularly, system circuits CQT1, CQT2,
CQT3, CQT4, COTS, COTk Which are provided to signal
transmission lines on respective channels shoWn in FIG. 2
to have the almost similar con?guration, a frequency char
acteristic correcting portion 11, a channel-to-channel level
correcting portion 12, a phase characteristic correcting por
[0042] Attenuators ATF11 to ATFlj being called an inter
band-pass ?lters BPF11 to BPFlj respectively. Accordingly,
the attenuators ATFM to ATFlJ- act as an in-channel level
adjusting means that adjusts respective output levels of the
band-pass ?lters BPFM to BPFlj.
[0043] Also, the inter-band attenuators ATF11 to ATFlj are
provided correspondingly to the band-pass ?lters BPF11 to
BPFlj, and thus variable gain type frequency discriminating
means are composed of the band-pass ?lters and the inter
band attenuators that correspond mutually. In other Words,
BPF11 and ATF11 constitute a ?rst variable gain type fre
quency discriminating means, BPF12 and ATF12 constitute a
second variable gain type frequency discriminating means,
. . . , and BPFlj and ATFlj constitute a j-th variable gain type
frequency discriminating means.
[0044] Also, an adder ADD1 is connected to output con
tacts of the inter-band attenuators ATFM to ATFij, an attenu
ator ATG1 being called a channel-to-channel attenuator is
connected to an output contact of the adder ADD], and a
delay circuit DLY1 is connected to an output contact of the
channel-to-channel attenuator ATGl. Then, an output DFL
of the delay circuit DLY1 is supplied to the D/A converter
4FL shoWn in FIG. 1.
tion 13, and a ?atness correcting portion 14 shoWn in FIG.
3 are provided to the signal processing circuit 2. Then, the
automatic sound ?eld correcting system is constructed such
[0045] Then, as shoWn in the frequency characteristic
diagram of FIG. 5, the band-pass ?lters BPF11 to BPFlj are
formed by narroW band passing type secondary ButterWorth
that the frequency characteristic correcting portion 11, the
channel-to-channel level correcting portion 12, the phase
?lters Whose center frequencies are set to f1, f2, . . . ?, . . .
characteristic correcting portion 13, and the ?atness correct
ing portion 14 can control the system circuits CQT1, CQT2,
CQT3, CQT4, COTS, CQTk. In this case, in the folloWing
explanation, respective channels are denoted by numbers x
(léxék).
[0038] A con?guration of the system circuit COT1 pro
vided to the ?rst channel (x=1) Will be explained on behalf
of the system circuits. Such con?guration includes a sWitch
element SW12 that ON/OFF-controls an input of the digital
audio signal SFL from the sound source 1 and a sWitch
element SW11 that ON/OFF-controls an input of a noise
fj, respectively.
[0046] In other Words, the band-pass ?lters BPF11 to BPFlj
that have frequencies f1, f2, . . . ?, . . . fj as a center frequency
respectively are provided. Such frequencies f1, f2, . . . ?, . . .
fj are previously decided by dividing all frequency band of
the loudspeaker 6FL, that can reproduce over the loW fre
quency band to the middle/high frequency band, by any
number j. More particularly, the loW frequency band that is
less than about 0.2 kHZ is divided into about six ranges and
also the middle/high frequency band that is more than about
0.2 kHZ is divided into about seven ranges, and then the
center frequencies of respective divided narroW frequency
Aug. 23, 2001
US 2001/0016045 A1
ranges are set as the center frequencies f1, f2, . . . ?, . . . fj
of the band-pass ?lters BPF11 to BPFlj. In addition, all
frequency bands are covered Without ornission by setting the
center frequencies not to form clearances betWeen respective
passing frequency bands of the band-pass ?lters BPF11 to
BPFlj and not to overlap substantially respective passing
frequency bands.
[0047] Also, the band-pass ?lters BPFM to BPFlJ- can be
exclusively ON/OFF-sWitched rnutually under the control of
the system controller MPU. Also, in reproducing the audio
sound, all band-pass ?lters BPF1 1 to BPFlJ- are sWitched into
their conductive states.
[0048] The attenuators ATFM to ATFlJ- consist of a digital
attenuator respectively, and changes their attenuation factors
in the range of 0 dB to the (—) side in accordance With adjust
signals SF11 to SF1J- supplied from the frequency character
istic correcting portion 11.
[0049]
The adder ADD1 adds signals that are passed
through the band-pass ?lters BPF11 to BPFlj and attenuated
by the attenuators ATF11 to ATFlj and then supplies the
added signal to the attenuator ATGl.
[0050] The channel-to-channel attenuator ATG1 consists
of the digital attenuator. Although its details Will be given in
the explanation of operation, the channel-to-channel attenu
ator ATG1 changes its attenuation factor in the range of 0 dB
to the (—) side in compliance With the adjust signal SG1 from
the channel-to-channel level correcting portion 12.
ATF3j, the channel-to-channel attenuator ATG3, and the
delay circuit DLY3 are adjusted in compliance With adjust
signals SF31 to SF3J- supplied from the frequency character
istic correcting portion 11, an adjust signal SG3 supplied
from the channel-to-channel level correcting portion 12, and
an adjust signal SDL3 supplied from the phase characteristic
correcting portion 13 respectively.
[0055] FolloWing to the sWitch elernents SW41, SW42, j
variable gain type frequency discrirninating means that are
composed of j band-pass ?lters BPF41 to BPF4J- that are set
to the above center frequencies f1 to fj, and inter-band
attenuators ATF41 to ATF4J- are provided to the system
circuits CQT4 on the fourth channel (x=4). In addition, an
adder ADD4, an channel-to-channel attenuator ATG4, and a
delay circuit DLY4 are further provided. Then, like the
system circuit CQT1, the inter-band attenuators ATF41 to
ATF4j, the channel-to-channel attenuator ATG4, and the
delay circuit DLY4 are adjusted in compliance With adjust
signals SF41 to SF4J- supplied from the frequency character
istic correcting portion 11, an adjust signal SG4 supplied
from the channel-to-channel level correcting portion 12, and
an adjust signal SDL4 supplied from the phase characteristic
correcting portion 13 respectively.
[0056] FolloWing to the sWitch elernents SW51, SW52, j
variable gain type frequency discrirninating means that are
composed of j band-pass ?lters BPF51 to BPFSJ- that are set
to the above center frequencies f1 to fj, and inter-band
attenuators ATF51 to ATFSJ- are provided to the system
circuits CQT5 on the ?fth channel (x=5). In addition, an
[0051] The delay circuit DLY1 consists of the digital delay
adder ADDS, an channel-to-channel attenuator ATG5, and a
circuit, and changes its delay time in compliance With the
delay circuit DLY5 are further provided. Then, like the
system circuit CQT1, the inter-band attenuators ATF51 to
ATFsj, the channel-to-channel attenuator ATG5, and the
delay circuit DLY5 are adjusted in compliance With adjust
adjust signal SDL1 supplied from the phase characteristic
correcting portion 13.
[0052] Then, the system circuits CQT2, CQT3, CQT4,
CQT5 on rernaining channels x=2 to 5 have a similar con
?guration to the system circuit CQT1.
[0053] More particularly, although shoWn simply in FIG.
2, folloWing to the sWitch elernents SW21, SW22, j variable
gain type frequency discrirninating means that are composed
of j band-pass ?lters BPF21 to BPFZJ- that are set to the above
center frequencies f1 to fj and inter-band attenuators ATF21
to ATFZJ- that change their attenuation factors in the range of
0 dB to the (—) side in compliance With adjust signals SF21
to SFZJ- supplied from the frequency characteristic correcting
portion 11 respectively are provided to the system circuits
CQT2 on the second channel (x=2). In addition, an adder
ADD2, an channel-to-channel attenuator ATG2 that changes
its attenuation factor in the range of 0 dB to the (—) side in
compliance With an adjust signal SG2 supplied from the
channel-to-channel level correcting portion 12, and a delay
circuit DLY2 that changes its delay time in compliance With
an adjust signal SDL2 supplied from the phase characteristic
correcting portion 13 are further provided.
signals SF51 to SFSJ- supplied from the frequency character
istic correcting portion 11, an adjust signal SG5 supplied
from the channel-to-channel level correcting portion 12, and
an adjust signal SDL5 supplied from the phase characteristic
correcting portion 13 respectively.
[0057] HoWever, the system circuit CQTk on the sixth
subWoofer channel (x=k) is constructed such that i (i<j)
band-pass ?lters BPFk1 to BPFkj, that pass only divided loW
frequency bands (frequencies beloW about 0.2 kHZ) shoWn
in FIG. 5 respectively, and inter-band attenuators ATFk1 to
ATFkJ- are connected in parallel folloWing to the sWitch
elernents SW1d, SWk2, then an adder ADDk adds outputs of
the attenuators ATFk1 to ATFki, then an output of the added
result is passed through a channel-to-channel attenuator
ATGk and a delay circuit DLYk, and then an output DWF of
the delay circuit DLYk is supplied to the D/A converter 4WF.
[0058] In this case, i variable gain type frequency dis
crirninating means are composed of band-pass ?lters BPFk1
to BPFki and inter-band attenuators ATFk1 to ATFki.
[0054] FolloWing to the sWitch elernents SW31, SW32, j
[0059] Next, in FIG. 3, the frequency characteristic cor
variable gain type frequency discrirninating means that are
composed of j band-pass ?lters BPF31 to BPF3J- that are set
to the above center frequencies f1 to fj, and inter-band
attenuators ATF31 to ATF3j respectively are provided to the
system circuits CQT3 on the third channel (x=3). In addition,
recting portion 11 receives respective sound collecting data
DM obtained When the loudspeakers 6FL, 6FR, 6c, 6R1“, 6RR,
6WF are sounded individually by the noise signal (pink
an adder ADD3, an channel-to-channel attenuator AT G3, and
a delay circuit DLY3 are further provided. Then, like the
system circuit CQT1, the inter-band attenuators ATF31 to
noise) DN output from the noise generator 3, and then
calculates levels of the reproduced sounds of respective
loudspeakers at the listening position RV based on the sound
collecting data DM. Then, the frequency characteristic cor
recting portion 11 generates the adjust signals SF11 to SP1],
US 2001/0016045 A1
Aug. 23, 2001
SF21 to SFZJ, . . . , SFk1 to SFki based on these calculated
collecting data DM3 and DM1, . . . , the cross correlation
results to correct automatically the attenuation factors of the
betWeen the sound collecting data DMk and DM1 are cal
inter-band attenuators AT F11 to AT Flj, ATF21 to ATFZJ, . . . ,
culated, and then peak intervals (phase differences) betWeen
ATFk1 to ATFki individually.
respective correlation values are set as their delay times '52
[0060]
to "5k in respective system circuits COT2 to CQTk. That is,
the delay times '52 to "5k of remaining system circuits COT2
Based on the above correction of the attenuation
factors by the frequency characteristic correcting portion 11,
gain adjustment for respective passing frequencies of the
band-pass ?lters BPFM to BPFki provided to the system
circuits CQT1 to COTk is carried out every channel.
[0061] That is, the frequency characteristic correcting
portion 11 adjusts the levels of respective signals output
from the band-pass ?lters BPF11 to BPFki by performing the
gain adjustment of the inter-band attenuators ATF1 1 to ATFki
serving as an in-channel level adjusting means, Whereby the
frequency characteristic correcting portion 11 acts as an
in-channel level correcting means for setting the frequency
characteristic.
to COTk are calculated on the basis of the phase of the sound
collecting data DM1 obtained from the system circuit CQT1
(i.e., phase difference 0, "c1=0) . Then, the adjust signals
SDL1 to SDLk are generated based on measured results of
these delay times '52 to "5k, and then the phase characteristic
of the sound ?eld space is corrected by automatically
adjusting respective delay times of the delay circuits DLY1
to DLYk by using these adjust signals SDL1 to SDLk. In this
case, the uncorrected noise is employed to correct the phase
characteristic in the present embodiment, but either the noise
pink noise or other noise may be employed.
[0068] The ?atness correcting portion 14 adjusts the
[0062] The channel-to-channel level correcting portion 12
attenuation factor of the channel-to-channel attenuator ATGk
receives respective sound collecting data DM obtained When
in the system circuit CQTk, that is not adjusted by the
channel-to-channel level correcting portion 12, after the
all frequency band loudspeakers 6FL, 6FR, 6c, 6RL, 6RR are
sounded individually by the noise signal (pink noise) DN
output from the noise generator 3, and then calculates the
levels of the reproduced sounds of respective loudspeakers
at the listening position RV based on the sound collecting
data DM. Then, the channel-to-channel level correcting
portion 12 generates the adjust signals SG1 to SG5 based on
these calculated results and corrects automatically the
attenuation factors of the channel-to-channel attenuators
ATG1 to ATGSby the adjust signals SG1 to SGS.
[0063]
Based on the correction of the attenuation factors
by the channel-to-channel level correcting portion 12, the
level adjustment (gain adjustment) betWeen the system
adjustments made by the frequency characteristic correcting
portion 11, the channel-to-channel level correcting portion
12, and the phase characteristic correcting portion 13 have
been completed.
[0069] That is, as shoWn in FIG. 4, the ?atness correcting
portion 14 comprises a middle/high frequency band pro
cessing portion 15a, a loW frequency band processing por
tion 15b, a subWoofer loW frequency band processing por
tion 15c, and a calculating portion 15d.
[0070] In the state that the loW frequency band-pass ?lters
BPF11 to BPFli, BPF21 to BPFZi, BPF31 to BPF3i, BPF41 to
BPF4i, BPF51 to BPF5i provided to the system circuits CQT1
circuits COT1 to COT5 on the ?rst to ?fth channels is carried
to CQT5 are turned OFF and the remaining middle/high
out.
frequency band-pass ?lters are turned ON, the middle/high
frequency band processing portion 15a measures a spectrum
average level PMH of the reproduced sound in the middle/
high frequency band from the sound collecting data DM
(referred to as “middle/high frequency band sound collect
ing data DMH” hereinafter) that are obtained When all
[0064] That is, the channel-to-channel level correcting
portion 12 acts as a channel-to-channel level correcting
means that corrects levels of the audio signals transmitted
every channel (signal transmission line) betWeen channels.
[0065] HoWever, the channel-to-channel level correcting
frequency band loudspeakers 6FL, 6FR, 6c, 6RL, 6RR are
portion 12 does not adjust the attenuation factor of the
channel-to-channel attenuator ATGk provided to the system
circuit COTk on the subWoofer channel, but the ?atness
sounded simultaneously based on the noise signal (uncor
related noise) DN output from the noise generator 3.
correcting portion 14 adjusts the attenuation factor of the
channel-to-channel attenuator ATGk.
[0066] The phase characteristic correcting portion 13 mea
sures the phase characteristic of respective channels based
on respective sound collecting data DM obtained When
[0071] In the state that the loW frequency band-pass ?lters
BPF11 to BPFli, BPF21 to BPFZi, BPF31 to BPF3i, BPF41 to
BPF4i, BPF51 to BPF5i provided to the system circuits CQT1
to COT5 are turned ON and the remaining middle/high
frequency band-pass ?lters are turned OFF, the loW fre
respective loudspeakers 6FL, 6FR, 6c, 6RL, 6RR, 6WF are
sounded individually by supplying the noise signal (uncor
quency band processing portion 15b measures a spectrum
average level PL of the reproduced sound in the loW fre
quency band from the sound collecting data DM (referred to
related noise) DN output from the noise generator 3 to the
system circuits CQT1 to COTk on respective channels, and
as “loW frequency band sound collecting data DL” herein
after) that are obtained When all frequency band loudspeak
then corrects the phase characteristic of the sound ?eld space
in compliance With the measured result.
ers 6FL, 6FR, 6c, 6RL, 6RR are sounded simultaneously based
on the noise signal (uncorrelated noise) DN output from the
noise generator 3.
[0067] More particularly, the loudspeakers 6FL, 6FR, 6c,
6RL, 6RR, 6WF on respective channels are sounded by the
noise signal DN every period T, and then cross correlations
betWeen resultant sound collecting data DM1, DMZ, DM3,
DM4, DM5, DMk on respective channels are calculated.
Here, the cross correlation betWeen the sound collecting data
DM2 and DM1, the cross correlation betWeen the sound
[0072] In the condition that all band-pass ?lters BPFk1 to
BPFki provided to the system circuit COTk on the subWoofer
channel are turned ON, the loW frequency band processing
portion 15c measures a spectrum average level PWFL of the
loW sound reproduced only by the loudspeaker 6WF from the
sound collecting data DM (referred to as “subWoofer sound
Aug. 23, 2001
US 2001/0016045 A1
collecting data DWFL” hereinafter) that are obtained When
the loW frequency exclusively reproducing loudspeaker 6WF
is sounded based on the noise signal (pink noise) DN output
from the noise generator 3.
to the system circuits CQT1, CQT2, CQT3, CQT4, COTS,
COTk is carried out by the frequency characteristic correct
ing portion 11.
[0080] Then, in the channel-to-channel level correcting
signal SGk that makes the frequency characteristic of the
process in step S20, the process for adjusting the attenuation
factors of the channel-to-channel attenuators ATG1 to ATG5
reproduced sound at the listening position RV ?at over all
provided to the system circuits CQT1, CQT2, CQT3, CQT4,
audio frequency bands When all loudspeakers 6FL, 6FR, 6c,
6RL, 6RR, 6WF are sounded simultaneously, by executing
predeterrnined calculating processes explained later in detail
ing portion 12. That is, in step S20, the channel-to-channel
[0073] The calculating portion 15d generates the adjust
based on the spectrum average level PMH in the above
rniddle/high frequency band and the spectrum average levels
PL, PWFL in the loW frequency bands.
[0074]
That is, as shoWn in the frequency characteristic
diagram of FIG. 6, since the all frequency band loudspeak
ers 6FL, 6FR, 6c, 6RL, 6RR have not only the rniddle/high
frequency band reproducing capability but also the loW
COT5 is carried out by the channel-to-channel level correct
attenuator ATGk provided to the system circuit COTk on the
subWoofer channel is not adjusted.
[0081] Then, in the phase characteristic correcting process
in step S30, the process for adjusting the delay times of all
delay circuits DLY1 to DLYk provided to the system circuits
CQT1, CQT2, CQT3, CQT4, COTS, COTk is carried out by
the phase characteristic correcting portion 13. That is, the
process for correcting the phase characteristic of the repro
frequency band reproducing capability, in some cases the
spectrum average level of the loW frequency sounds repro
duced sound being reproduced by all loudspeakers 6FL to
duced by the loudspeakers 6FL, 6FR, 6c, 6RL, 6RR and the
loW frequency sound reproduced by the loudspeaker 6WF,
[0082] Then, in the ?atness correcting process in step S40,
6WP is performed.
for example, becorne higher than the spectrum average level
of the reproduced sound in the rniddle/high frequency band
the process for making the frequency characteristic of the
reproduced sound at the listening position RV ?at over the
full audio frequency band is carried out by the ?atness
if these loudspeakers 6FL, 6FR, 6c, 6RL, 6RR and the loW
correcting portion 14.
frequency band exclusively reproducing loudspeaker 6WF
are sounded. Thus, there is caused such a problem that such
loW frequency sounds are offensive to the ear and also give
the listener an unpleasant feeling. Therefore, the calculating
portion 15d adjusts the attenuation factor of the channel-to
channel attenuator ATGk by the adjust signal SGk such that
the spectrum average level of the above loW frequency
sounds and the spectrum average level of the rniddle/high
[0083] In this manner, the present automatic sound ?eld
correcting systern executes the sound ?eld correction by
performing in sequence the correcting processes that are
roughly classi?ed into four stages.
[0084] Then, respective processes in steps S10 to S40 Will
be explained in sequence.
frequency sounds can be made ?at.
[0085] First, the frequency characteristic correcting pro
[0075] Accordingly, the ?atness correcting portion 14 as
cess in step S10 Will be explained in detail. The process in
step S10 Will be carried out in compliance With the detailed
?oWchart shoWn in FIG. 9.
Well as the channel-to-channel level correcting portion 12
acts as the channel-to-channel level correcting means that
corrects the levels of the audio signals, that are transmitted
every channel (signal transmission line), betWeen the chan
[0086]
In step S100, the initialiZation process is executed
to set the attenuation factors of all inter-band attenuators
nels.
ATF11 to ATFki and the channel-to-channel attenuators ATG1
[0076] In this case, the con?guration of the automatic
sound ?eld correcting system is explained, but more detailed
functions Will be explained in detail in the explanation of
COTS, COTk shoWn in FIG. 2 to 0 dB. Also, the delay times
in all delay circuits DLY1 to DLYk are set to 0, and the
operation.
FIG. 1 are set equal.
[0077]
[0087] In addition, the sWitch elernents SW12, SW22,
SW32, SW42, SW52, SWk2 are turned OFF (nonconductive)
to ATGk in the system circuits CQT1, CQT2, CQT3, CQT4,
Next, an operation of the automatic sound ?eld
correcting system having such con?guration Will be
arnpli?cation factors of the arnpli?ers SFL to SWF shoWn in
explained With reference to ?oWcharts shoWn in FIG. 8 to
FIG. 12 hereunder.
to cut off the input from the sound source 1, and the sWitch
[0078] When, as shoWn in FIG. 7, for example, the
listener arranges a plurality of loudspeakers 6FL to 6WF in the
signal (pink noise) DN generated by the noise generator 3 is
supplied to the system circuits CQT1, CQT2, CQT3, CQT4,
elernents SWN is turned ON (conductive). Accordingly, the
signal processing circuit 2 is set to the state that the noise
listening room 7, etc., connects them to the present audio
system, and then instructs to start the sound ?eld correction
by operating a remote controller (not shoWn) provided to the
present audio system, the system controller MPU operates
the automatic sound ?eld correcting system in compliance
With this instruction.
[0079] First, an outline of the operation of the automatic
sound ?eld correcting system will be explained With refer
COTS, CQTk.
[0088] Then, the process goes to step S102, and ?ag data
n=0 is set in a ?ag register (not shoWn) built in the system
controller MPU.
[0089] Then, the sound ?eld characteristic rneasuring pro
cess is executed in step S104.
[0090] In this step S104, the noise signal DN is supplied
ence to FIG. 8. In the frequency characteristic correcting
in sequence to the system circuits COT1 to COTk by exclu
process in step S10, the process for adjusting the attenuation
factors of all inter-band attenuators ATF11 to ATFkj provided
sively turning ON the sWitch elernents SW11, SW21, SW31,
SW41, SW51, SWk1 for the predetermined period T respec
Aug. 23, 2001
US 2001/0016045 A1
tively. Also, the band-pass ?lters in the system circuit to
Which the noise signal DN is being supplied are exclusively
are not executed. The processes in steps S106 to S124 are
turned ON in sequence from the loW frequency band side to
decided as the large loudspeaker are connected.
the middle/high frequency band side.
[0091] Accordingly, the noise signal DN that is frequency
divided by the band-pass ?lters BPFM to BPFlJ- in the system
circuit CQT1 is supplied to the loudspeaker 6FL sequentially.
As a result, the microphone 8 collects the noise sound that
is produced at the listening position RV and is frequency
divided, and the D/A converter 10 supplies these sound
collecting data DM (referred to as “DM11 to DM11?’ herein
after) to the frequency characteristic correcting portion 11.
Then, the frequency characteristic correcting portion 11
stores these sound collecting data DM11 to DMlj in a
predetermined memory portion (not shoWn).
applied only to the channels in Which the loudspeakers being
[0097] In order to facilitate the understanding of explana
tion, the processes in steps S106 to S124 Will be explained
under the assumption that all the loudspeakers 6FL, 6FR, 6c,
6RL, 6RR, 6WF are the large loudspeaker.
[0098] Then, in step S106, the listener sets target curve
data [TG><J] that are set previously in the present audio
system into the frequency characteristic correcting portion
11. Where the target curve denotes the frequency character
istic of the reproduced sound that can suit the listener’s taste.
In the present audio system, in addition to the target curve
used to generate the reproduced sound having the frequency
and then resultant sound collecting data DM (referred to as
characteristic that is suitable for the classic music, various
target curve data [TG><J] used to generate the reproduced
sounds having the frequency characteristics that are suitable
for rock music, pops, vocal, etc. are stored in the system
controller MPU. Also, these target curve data [TG><J] consist
“DM21 to DMZj, DM31 to DM3j, DM41 to DM41, DM51 to
DM51, DMk1 to DMki” hereinafter) on respective channels
of an aggregation of the data of the same number as the
inter-band attenuators ATF11 to ATFki, as shoWn by a matrix
are stored in the predetermined memory portion (not
in Eq. (2), and they can be selected every channel indepen
shoWn).
dently.
[0092] Also, similarly the noise signal DN that is sub
jected to the frequency division is supplied to the loudspeak
ers 6FR to 6WF via remaining system circuits CQT2 to CQTk,
[0093] In this manner, the sound collecting data [DA><J]
expressed by a matrix in Eq. (1) are stored in the frequency
characteristic correcting portion 11 by executing the sound
?eld characteristic measuring process. In this case, a suf?x
x in [DA><J] denotes the channel number (1 éxék), and a
suffix J denotes the order of the center frequencies f1 to fj
from the loW frequency band to the middle/high frequency
band.
[DAxJ]:
DM11
DMZ]
DM31
DM41
DM51
DMk]
DM];
DMZ;
DM3;
_
DM4;
DM5;'
(1)
DMki
[0099]
Then, the listener can select these target curves
freely by operating predetermined operation buttons of a
remote controller. Then, the system controller MPU sets the
selected target curve data [TG><J] onto the frequency char
acteristic correcting portion 11.
[0100] HoWever, if the listener instructs the sound ?eld
correction Without selection of the target curve, all data TG11
to TGki are set to a previously decided value, e.g., 1.
[0094] In addition, in step S104, the sound collecting data
[DA><J] are compared With predetermined threshold value
THDCH every channel, and siZes of the loudspeakers 6FL to
[0101] Then, in step S108, the frequency characteristic
correcting portion 11 sets the number of the ?rst channel
(x=1) and the order of the ?rst center frequency (J=1), and
6WP on respective channels are decided based on the com
then calculates the adjust values F0 (1,1) to F0(1,j) by
parison results. That is, since the sound pressure of the
repeating processes in steps S110 to S114 to adjust the
inter-band attenuators ATFM to ATFlj.
reproduced sound reproduced by the loudspeaker is changed
according to the siZe of the loudspeaker, the siZes of the
loudspeakers on respective channels are decided.
[0102]
More particularly, if the ?rst line data DM11 to
DMlj in the sound collecting data [DA><J] given by above Eq.
As the concrete deciding means, an average value
(1) and the ?rst line data TG11 to TGlj in the target curve data
of the sound collecting data DM11 to DMlj on the ?rst
channel in above Eq. (1) is compared With the threshold
value THDCH. If the average value is smaller than the
threshold value THDCH, the loudspeaker 6FL is decided as
the small loudspeaker. Then, if the average value is larger
than the threshold value THDCH, the loudspeaker 6FL is
decided as the large loudspeaker. In addition, remaining
[0095]
[TGA><J] given by above Eq.(2) are applied to folloWing
loudspeakers 6FR, 6c, 6RL, 6RR, 6WF are similarly decided.
[0096] Then, in the channels in Which the loudspeakers
being decided as the small loudspeaker are connected,
processes in steps S106 to S124 described in the folloWing
Eq.(3) While changing the variable J betWeen 1 to j in steps
S112 and S114 after the ?ag data n is set to 0 and a variable
x representing the channel is set to 1, the adjust values
F0(1,1) to F0(1,j) of the inter-band attenuators ATF11 to
ATFlj corresponding to the ?rst channel are calculated. HoW
ever, if a value TG><J/DM><J calculated by Eq. (3) has a
calculation error that is smaller than the predetermined
threshold value THD, the value TG><J/DM><J is forcedly set
to 0 to achieve the improvement in the adjust precision.
Aug. 23, 2001
US 2001/0016045 A1
[0103] Then, in step S112, if it is decided that all adjusted
values F0(1, 1) to F0(1,
of the inter-band attenuators
ATF11 to ATFlj on the ?rst channel have been calculated, the
[FNIxJ] :
(6)
process goes to step S116. Then, it is decided Whether or not
the adjusted values of all inter-band attenuators on the
second to sixth channels (x=2 to k) have been calculated. If
NO, the variable X is incremented by 1 and the variable j is
set to 1 in step S118, and then the processes from step S110
to step S116 are repeated. Then, if the calculation of the
adjusted values of all inter-band attenuators is ?nished, the
process goes to step S120.
[0104] Accordingly, the adjusted values [FOxJ] of all
[0109] Then, in step S126, adjust data [SF><J] used to
inter-band attenuators ATF11 to ATFlj represented by the
adjust the attenuation factors of all inter-band attenuators
matrix given by folloWing Eq.(4) are calculated.
ATF11 to AT Flj, . . . , ATFk1 to ATFki of the system circuits
CQT1 to CQTk shoWn in Eq. (7) are calculated by multi
plying the normaliZed adjusted values [FNOXJ] by the nor
maliZed adjusted values [FNlxJ] in respective matrices.
[0105] Then, in step S120, the adjusted values [FOxJ] are
normaliZed by executing the calculation represented by the
matrix in folloWing Eq. (5), and then resultant normaliZed
[0110]
adjusted values [FNOXJ] are set as neW target curve data
column of the matrix in Eq. (7) is calculated by multiplying
[TG><J]=[FNO><J]. That is, the target curve data [TG><J] in
above Eq. (2) are replaced With the normaliZed adjusted
of the normaliZed adjusted values [FNOXJ] and [FN1><J ]
values [FNOxJ].
That is, a value SF11 on the ?rst roW and the ?rst
a value F0(1,1)/F01max on the ?rst roW and the ?rst column
shoWn in Eqs. (5) (6) by a F1(1,1)/F11max, and then a value
SF21 on the second roW and the ?rst column of the matrix
in Eq.(7) is calculated by multiplying a value F0 (2,1)
/F02max on the second roW and the ?rst column by a F1
(2,1)/F12max. In the subsequent, adjust data [SF><j] used for
the attenuation factor adjustment represented by the matrix
in Eq. (7) are calculated by executing the similar calculation
in the folloWing.
[0111]
Then, the attenuation factors if the inter-band
attenuators ATF11 to ATFlj, . . . ,ATFk1 to ATFki are adjusted
according to respective adjust signals SFM to SP1], . . . , SFk1
to SFki based on the adjust data [SF><J], and then the process
goes to step S20 in FIG. 8.
[0106]
In this case, values FOlmax to FOkmax having a
suffix “max” in Eq. (5) are maximum values of the adjusted
values on respective channels x=1 to k When the ?ag data n
is n=1.
[0107] Then, in step S122, it is decided Whether or not the
?ag data n is 1. If NO, the ?ag data n is set to 1 in step S124,
and then the processes starting from step S104 are repeated.
[0108] In this manner, the processes in step S104 and
subsequent steps are repeated. In step S122, if it is decided
that the ?ag data n is 1, the process goes to step S126. While,
if the processes in step S104 and subsequent steps are
repeated, the ?ag data n is set to n=1 and thus the calcula
tions in above Eqs. (1) to (5) are executed once again. Thus,
the normaliZed adjusted values [FN1><J ] in folloWing Eq. (6)
corresponding to above Eq.(S) are calculated.
[0112] Also, in the foregoing sound ?eld characteristic
measuring process in step S104, if the channel in Which the
small loudspeaker is connected is decided, the attenuation
factors of the inter-band attenuators provided in the channels
are adjusted to 0 dB, While the attenuation factors of the
inter-band attenuators in the channels in Which the large
loudspeakers are connected are adjusted based on the adjust
data [SF><J
[0113] In step S104, if it is decided that the loudspeakers
6FL, 6FR, 6c, 6RL, 6RR, 6WF on all channels are all small
loudspeakers, the process goes directly to the processes from
step S104 to step S126 Without executing steps S106 to
S124. In step S126, the attenuation factors of the inter-band
attenuators on all channels are adjusted to 0 dB.
[0114] In this Way, the frequency characteristics of respec
tive channels are corrected by adjusting the attenuation
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