Audio system, audio signal processing device and method, and program
An audio system including a first speaker and a second speaker that are arranged in front of a predetermined listening position to be substantially bilaterally symmetrical with respect to the listening position; a third speaker and a fourth speaker that are arranged in front of the predetermined listening position to be substantially bilaterally symmetrical with respect to the listening position; a first attenuator that attenuates components that are equal to or less than a predetermined first frequency of an input audio signal; and an output controller that outputs sounds that are based on the input audio signal from the first speaker and the second speaker and outputs sounds that are based on the first audio signal in which components that are equal to or less than the first frequency of the input audio signal from the third speaker and the fourth speaker.
1. An audio system comprising:
a first speaker and a second speaker that are arranged in front of a predetermined listening position to be substantially bilaterally symmetrical with respect to the listening position;
a first attenuator that attenuates components that are equal to or less than a predetermined first frequency of an input audio signal;
a signal processor that generates, based on the components attenuated by the first attenuator, signals correlated with a first virtual speaker output location and a second virtual speaker output location that are arranged in front of the predetermined listening position to be substantially bilaterally symmetrical with respect to the listening position such that, with the listening position being a center, a center angle that is formed by connecting the listening position with each of the first virtual speaker output location and the second virtual speaker output location is greater than a center angle that is formed by connecting the listening position with the first speaker and the second speaker, and the first virtual speaker output location and the second virtual speaker output location are positioned to be closer in a longitudinal direction of the listening position to the listening position than the first speaker and the second speaker; and
an output controller that controls to output, from the first speaker and the second speaker, sounds that are based on the input audio signal, and to output for reproduction as emanating from the first virtual speaker output location and from the second virtual speaker output location, sounds that are based on a first audio signal in which components that are equal to or less than the first frequency of the input audio signal have been attenuated,
wherein the sounds that are output for reproduction as emanating from the first virtual speaker output location and from the second virtual speaker output location are generated based on respective audio signals obtained by superimposing respective head-related transfer functions on the attenuated input audio signal, and
wherein the respective head-related transfer functions are superimposed on the attenuated input audio signal such that the sounds that are output for reproduction have a ratio between direct audio signals and indirect audio signals determined based on a distance in the longitudinal direction from the listening position to the first virtual speaker output location and to the second virtual speaker output location.
2. The audio system according to claim 1 , further comprising:
a second attenuator that attenuates components that are equal to or greater than a predetermined second frequency of the input audio signal,
wherein the output controller controls to output, from the first speaker and the second speaker, sounds that are based on a second audio signal in which components that are equal to or greater than the second frequency of the input audio signal have been attenuated.
3. The audio system according to claim 1 ,
wherein the first speaker, second speaker, first virtual speaker output location, and second virtual speaker output location are arranged such that the distance between the first virtual speaker output location and the listening position and the distance between the second virtual speaker output location and the listening position are less than the distance between the first speaker and the listening position or the distance between the second speaker and the listening position.
4. The audio system according to claim 1 , wherein the signal processor performs predetermined signal processing with respect to the first audio signal in generating the correlated signals, which when reproduced by the first speaker and the second speaker, causes the first speaker and the second speaker to output sounds that appear to a person at the listening position to virtually emanate from the first virtual speaker output location and from the second virtual speaker output location.
5. The audio system according to claim 1 ,
wherein the head-related transfer functions comprises a first head-related transfer function HLL and a second head-related transfer function HLR,
wherein an audio signal SL 1 Rb that corresponds to direct sounds reaching a right ear of a listener at the listening position is determined based on the following equation:
SL
1
Rb
[
n
]
=
∑
m
=
0
dLR
(
SL
1
[
n
-
m
]
*
HLR
[
m
]
)
where n is a number of samples, SL 1 represents the attenuated input audio signal for the left ear of the listener at the listening position, dLR represents a next number of the head-related transfer function HLR, and
wherein an audio signal SL 1 Lb that corresponds to direct sounds reaching a left ear of a listener at the listening position is determined based on the following equation:
SL
1
Lb
[
n
]
=
∑
m
=
0
dLL
(
SL
1
[
n
-
m
]
*
HLL
[
m
]
)
where dLL represents a next number of the head-related transfer function HLL.
6. An audio signal processing device comprising:
an attenuator that attenuates components of an input audio signal that are equal to or less than a predetermined frequency; and
an output controller that controls to output, from a first speaker and a second speaker, sounds that are based on the input audio signal, and to output for reproduction as emanating from a first virtual speaker output location and from a second virtual speaker output location, sounds that are based on an audio signal in which components that are equal to or less than the predetermined frequency of the input audio signal are attenuated,
wherein the first speaker and the second speaker are arranged in front of a predetermined listening position to be substantially bilaterally symmetrical to the listening position,
wherein the first virtual speaker output location and the second virtual speaker output location are arranged in front of the listening position to be substantially bilaterally symmetrical with respect to the listening position such that, with the listening position being a center, a center angle that is formed by connecting the listening position with the first virtual speaker output location and the second virtual speaker output location is greater than a center angle that is formed by connecting the listening position with the first speaker and the second speaker, and the first virtual speaker output location and the second virtual speaker output location are positioned to be closer in a longitudinal direction of the listening position to the listening position than the first speaker and the second speaker, and
wherein the sounds that are output for reproduction as emanating from the first virtual speaker output location and from the second virtual speaker output location are generated based on respective audio signals obtained by superimposing respective head-related transfer functions on the attenuated input audio signal, and
wherein the respective head-related transfer functions are superimposed on the attenuated input audio signal a such that the sounds that are output for reproduction have a ratio between direct audio signals and indirect audio signals determined based on a distance in the longitudinal direction from the listening position to the first virtual speaker output location and to the second virtual speaker output location.
7. The audio signal processing device according to claim 6 ,
wherein the head-related transfer functions comprises a first head-related transfer function HLL and a second head-related transfer function HLR,
wherein an audio signal SL 1 Rb that corresponds to direct sounds reaching a right ear of a listener at the listening position is determined based on the following equation:
SL
1
Rb
[
n
]
=
∑
m
=
0
dLR
(
SL
1
[
n
-
m
]
*
HLR
[
m
]
)
where n is a number of samples, SL 1 represents the attenuated input audio signal for the left ear of the listener at the listening position, dLR represents a next number of the head-related transfer function HLR, and
wherein an audio signal SL 1 Lb that corresponds to direct sounds reaching a left ear of a listener at the listening position is determined based on the following equation:
SL
1
Lb
[
n
]
=
∑
m
=
0
dLL
(
SL
1
[
n
-
m
]
*
HLL
[
m
]
)
where dLL represents a next number of the head-related transfer function HLL.
8. An audio signal processing method comprising:
attenuating components of an input audio signal that are equal to or less than a predetermined frequency; and
controlling to output, from a first speaker and a second speaker, sounds that are based on the input audio signal, and to output for reproduction as emanating from a first virtual speaker output location and from a second virtual speaker output location, sounds that are based on an audio signal in which components that are equal to or less than the predetermined frequency of the input audio signal are attenuated,
wherein the first speaker and the second speaker are arranged in front of a predetermined listening position to be substantially bilaterally symmetrical to the listening position,
wherein the first virtual speaker output location and the second virtual speaker output location are arranged in front of the listening position to be substantially bilaterally symmetrical with respect to the listening position such that, with the listening position being a center, a center angle that is formed by connecting the listening position with the first virtual speaker output location and the second virtual speaker output location is greater than a center angle that is formed by connecting the listening position with the first speaker and the second speaker, and the first virtual speaker output location and the second virtual speaker output location are positioned to be closer in a longitudinal direction of the listening position to the listening position than the first speaker and the second speaker, and
wherein the sounds that are output for reproduction as emanating from the first virtual speaker output location and from the second virtual speaker output location are generated based on respective audio signals obtained by superimposing respective head-related transfer functions on the attenuated input audio signal, and
wherein the respective head-related transfer functions are superimposed on the attenuated input audio signal such that the sounds that are output for reproduction have a ratio between direct audio signals and indirect audio signals determined based on a distance in the longitudinal direction from the listening position to the first virtual speaker output location and to the second virtual speaker output location.
9. The audio signal processing method according to claim 8 ,
wherein the head-related transfer functions comprises a first head-related transfer function HLL and a second head-related transfer function HLR,
wherein an audio signal SL 1 Rb that corresponds to direct sounds reaching a right ear of a listener at the listening position is determined based on the following equation:
SL
1
Rb
[
n
]
=
∑
m
=
0
dLR
(
SL
1
[
n
-
m
]
*
HLR
[
m
]
)
where n is a number of samples, SL 1 represents the attenuated input audio signal for the left ear of the listener at the listening position, dLR represents a next number of the head-related transfer function HLR, and
wherein an audio signal SL 1 Lb that corresponds to direct sounds reaching a left ear of a listener at the listening position is determined based on the following equation:
SL
1
Lb
[
n
]
=
∑
m
=
0
dLL
(
SL
1
[
n
-
m
]
*
HLL
[
m
]
)
where dLL represents a next number of the head-related transfer function HLL.
10. A non-transitory computer-readable medium having embodied thereon a program, which when executed by a computer causes the computer to execute a process of:
attenuating components of an input audio signal that are equal to or less than a predetermined frequency; and
controlling to output, from a first speaker and a second speaker, sounds that are based on the input audio signal, and to output for reproduction as emanating from a first virtual speaker output location and from a second virtual speaker output location, sounds that are based on an audio signal in which components that are equal to or less than the predetermined frequency of the input audio signal are attenuated,
wherein the first speaker and the second speaker are arranged in front of a predetermined listening position to be substantially bilaterally symmetrical to the listening position,
wherein the first virtual speaker output location and the second virtual speaker output location are arranged in front of the listening position to be substantially bilaterally symmetrical with respect to the listening position such that, with the listening position being a center, a center angle that is formed by connecting the listening position with the first virtual speaker output location and the second virtual speaker output location is greater than a center angle that is formed by connecting the listening position with the first speaker and the second speaker, and the first virtual speaker output location and the second virtual speaker output location are positioned to be closer in a longitudinal direction of the listening position to the listening position than the first speaker and the second speaker, and
wherein the sounds that are output for reproduction as emanating from the first virtual speaker output location and from the second virtual speaker output location are generated based on respective audio signals obtained by superimposing respective head-related transfer functions on the attenuated input audio signal, and
wherein the respective head-related transfer functions are superimposed on the attenuated input audio signal such that the sounds that are output for reproduction have a ratio between direct audio signals and indirect audio signals determined based on a distance in the longitudinal direction from the listening position to the first virtual speaker output location and to the second virtual speaker output location.
11. The non-transitory computer-readable medium according to claim 10 ,
wherein the head-related transfer functions comprises a first head-related transfer function HLL and a second head-related transfer function HLR,
wherein an audio signal SL 1 Rb that corresponds to direct sounds reaching a right ear of a listener at the listening position is determined based on the following equation:
SL
1
Rb
[
n
]
=
∑
m
=
0
dLR
(
SL
1
[
n
-
m
]
*
HLR
[
m
]
)
where n is a number of samples, SL 1 represents the attenuated input audio signal for the left ear of the listener at the listening position, dLR represents a next number of the head-related transfer function HLR, and
wherein an audio signal SL 1 Lb that corresponds to direct sounds reaching a left ear of a listener at the listening position is determined based on the following equation:
SL
1
Lb
[
n
]
=
∑
m
=
0
dLL
(
SL
1
[
n
-
m
]
*
HLL
[
m
]
)
where dLL represents a next number of the head-related transfer function HLL.