Electrical audio signal processing systems and devices – Binaural and stereophonic – Pseudo stereophonic
Reexamination Certificate
2001-04-27
2003-09-16
Harvey, Minsun Oh (Department: 2644)
Electrical audio signal processing systems and devices
Binaural and stereophonic
Pseudo stereophonic
C381S063000, C381S001000
Reexamination Certificate
active
06621906
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sound field generation system that generates a sound field space where the listener can receive spatial sound impression similar to that obtained in the case where the listener listens to music in, for example, a concert hall.
2. Description of the Related Art
As a sound field generation system of this kind, known is a sound field generation apparatus which is disclosed in JP-A-8-130799.
As shown in
FIG. 10A
, the sound field generation apparatus of the related art comprises reverberation generating circuits
1
and
2
which are called SFC processing circuits, filter circuits
3
and
4
, adders
5
and
6
, and amplifiers
7
and
8
, and is configured so as to operate two speakers
9
and
10
to generate sounds, thereby generating a reproduction sound field where spatial sound impression can be obtained.
Each of the reverberation generating circuits
1
and
2
comprises a delaying circuit
13
having multistage delay elements D
1
to Dn shown in FIG.
10
B. Plural delayed outputs with respect to an input signal Sin are added to one another in a predetermined combination relationship, to generate signals for two channels which are provided with reverberation characteristics.
The reverberation generating circuits
1
and
2
further comprise an attenuator and an all-pass filter. The amplitudes and phase characteristics of the signals for two channels are adjusted, so that a right-channel signal SR
1
and a left-channel signal SL
1
are generated and supplied to the adders
5
and
6
.
Each of the filter circuits
3
and
4
is configured by a variable filter which variably adjusts the gain of the right- or left-channel signals SR
1
or SL
1
in the audio frequency band as schematically shown in FIG.
10
C. The output of the filter circuit
3
is supplied to the adders
5
and
6
, that of the filter circuit
4
is supplied to the adder
6
, and an inverted output of the filter circuit
4
is supplied to the adder
5
.
According to this configuration, the adders
5
and
6
output right- and left-channel signals SR
2
and SL
2
which are similar to those recorded in, for example, a specific concert hall, and the signals SR
2
and SL
2
are supplied to the speakers
9
and
10
via the amplifiers
7
and
8
, respectively, thereby generating a reproduction sound field where the listener can receive spatial sound impression similar to that obtained in the case where the listener listens to music in the specific concert hall.
Microphones
11
and
12
pick up reproduced sounds which reach from the speakers
9
and
10
to the ears of the listener. On the basis of obtained pick-up signals PR and PL, an interaural correlation coefficient &rgr;RL is acquired. The frequency characteristics of the filter circuits
3
and
4
are adjusted so that the difference between an interaural correlation coefficient &rgr;RL′ which is previously acquired from the actual transfer function (frequency characteristics) of the specific concert hall, and the interaural correlation coefficient &rgr;RL becomes zero.
The transfer function (frequency characteristics) of a listening room or the like of the listener is different from that of the specific concert hall. Therefore, the frequency characteristics of the filter circuits
3
and
4
are adjusted so as to approximate the interaural correlation coefficient &rgr;RL of the reproduction sound field which is actually generated in the listening room or the like to the interaural correlation coefficient &rgr;RL′ of the specific concert hall, so that, even in a listening room or the like of the listener, a reproduction sound field where spatial sound impression similar to that obtained in the specific concert hall is obtained is generated.
In the sound field generation apparatus according to the related art, the frequency characteristics of the filter circuits
3
and
4
are adjusted in the following manner.
First, it is assumed that the interaural correlation coefficient &rgr;RL′ which is previously obtained from the actual transfer function (frequency characteristics) of the specific concert hall has the characteristics shown in FIG.
11
A. The transfer functions of the reverberation generating circuits
1
and
2
are previously set so as to coincide with the interaural correlation coefficient &rgr;RL′.
As shown in
FIG. 11B
, the passbands of the filter circuits
3
and
4
are set to a narrow band W
1
, and a stationary random signal of the narrow band is supplied as the input signal Sin for adjustment, thereby causing the speakers
9
and
10
to generate reproduced sounds based on the stationary random signal of the narrow band. The microphones
11
and
12
pick up the reproduced sounds, and the interaural correlation coefficient &rgr;RL is acquired on the basis of the obtained pick-up signals PR and PL. Thereafter, the difference between the interaural correlation coefficients &rgr;RL′ and &rgr;RL in the narrow band W
1
is acquired.
Similarly, the passbands of the filter circuits
3
and
4
are sequentially switched to narrow bands W
2
, W
3
, . . . , Wk in this sequence, the speakers
9
and
10
are caused at each of the switching operations to generate reproduced sounds based on the stationary random signal of the narrow band, and the differences between the interaural correlation coefficients &rgr;RL′ and &rgr;RL in the narrow bands W
2
, W
3
, . . . , Wk are acquired.
The gains of the filter circuits
3
and
4
for each of the narrow bands W
1
, W
2
, W
3
, . . . , Wk are adjusted so that the difference between the interaural correlation coefficient &rgr;RL which is actually acquired for each of the narrow bands W
1
, W
2
, W
3
, . . . , Wk, and the interaural correlation coefficient &rgr;RL′ of the concert hall or the like becomes zero, thereby adjusting the frequency characteristics of the filter circuits
3
and
4
in the whole audio frequency band. Namely, the frequency characteristics of the filter circuits
3
and
4
are adjusted in consideration of the transfer function (frequency characteristics) of a listening room or the like of the listener.
When the frequency characteristics of the filter circuits
3
and
4
are adjusted in this way, the adders
5
and
6
outputs the signals SR
2
and SL
2
which are obtained by finely adjusting the signals SR
1
and SL
1
that have been provided with reverberation characteristics of the listening room or the like, on the basis of the output signals of the filter circuits
3
and
4
. The speakers
9
and
10
are caused to generate sounds on the basis of the signals SR
2
and SL
2
, with the result that, even in the listening room or the like of the listener, a reproduction sound field where spatial sound impression similar to that obtained in the specific concert hall is obtained can be generated.
When a stationary random signal of the narrow band is supplied as the input signal Sin for adjustment and the passbands of the filter circuits
3
and
4
are set in the sequence of the narrow bands W
1
, W
2
, W
3
, . . . , Wk as described above, the interaural correlation coefficient &rgr;RL is acquired with including signal components in the overlapping portions of the narrow bands W
1
, W
2
, W
3
, . . . , Wk as indicated by the hatched areas in FIG.
11
C.
When the narrow bands W
1
and W
2
are considered, for example, since the bands overlap with each other, the interaural correlation coefficient &rgr;RL, which is acquired on the basis of the stationary random signal of the narrow band W
1
, contains influences of the stationary random signal in the narrow band W
2
, and the interaural correlation coefficient &rgr;RL, which is acquired on the basis of the stationary random signal of the narrow band W, contains influences of the stationary random signal in the narrow band W
1
. Also the interaural correlation coefficients &rgr;RL which are acquired for the other narrow bands W
2
, W
3
, . . . , Wk contain similar influences, respectively.
Even when the freq
Fukuchi Hiromi
Ohta Yoshiki
Harvey Minsun Oh
Pioneer Corporation
LandOfFree
Sound field generation system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sound field generation system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sound field generation system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3044870