Technical Field of the Invention
[0001] The present invention relates to a multi-channel audio signal correction device,
and more specifically to a multi-channel audio signal correction device to be used
in a multi-channel audio reproduction apparatus connected to a plurality of speakers
through a network so as to output sounds from the speakers.
Background of the Invention
[0002] Up until now, there have been a wide variety of multi-channel audio reproduction
apparatuses to provide a high-quality sound field space.
[0003] Fig.
12 is a diagram showing a conventional multi-channel audio reproduction apparatus including
a sound field correction unit 101, power amplifiers
102a to
102e, speakers
103a to
103e, and microphones
104a to
104d. Each of the power amplifiers
102a to
102e amplifies a measurement signal generated from measurement signal generator (not shown).
Each of the speakers
103a to
103e outputs the amplified measurement signal as sound. The microphones
104a to
104d are arranged in accordance with a closely located four point microphone method. Each
of the microphones
104a to 104d collects the sounds from all the speakers
103a to
103e. The sound field correction unit 101 compares characteristics of the sounds collected
by the microphones
104a to 104d with a volume of, a delay time of, and a mixing ratio of sounds set in a
controller (not shown), thereby obtaining differential signals of the comparison results.
Based on the differential signals, a sound volume controller, a delay circuit, and
a mixer (not shown) is controlled to automatically generate a optimal sound field
space at a listening point of a user (refer to, for example, Patent Document 1).
[0004] Fig. 13 is a diagram showing another conventional multi-channel audio reproduction
apparatus including a measurement signal generator
111, a switch
112, power amplifiers
113a to
113e, a speaker microphone switch
114, a front-left speaker
115a, a front-right speaker
115b, a front-center speaker
115c, a rear-left speaker
115d, a rear-right speaker
115e, microphones
116a and
116b, head amplifiers
117a to
117e, a delay measurement unit
118, a processing unit
119, a listening position input unit
120, and an output signal processing unit
121. Each of the switch
112 and the speaker microphone switch
114 selects one of speakers
115a to
115e. The measurement signal generator
111 generates a measurement signal. Each of the power amplifiers
113a to
113e amplifies the measurement signal generated by the measurement signal generator
111. The selected speaker outputs the amplified measurement signal. The speaker microphone
switch
114 connects an output terminal of each of the speakers
115a to
115e other than the selected speaker to a corresponding one of the head amplifiers
117a to
117e. Each of the speakers connected to the corresponding head amplifiers operates as
a microphone to collect the measurement signal output from the selected speaker. Each
of the head amplifiers
117a to
117e amplifies the collected measurement signal to transmit the amplified measurement
signal to the delay measurement unit
118. The microphone
116a and
116b are mounted in the rear-left speaker
115d and the rear-right speaker
115e, respectively. Both of the microphones
116a and
116b collect the measurement signal output from the selected speaker. The head amplifiers
117f and
117g receive the measurement signal from the microphones
116a and
116b to amplify the received measurement signal, respectively. Both of the head amplifiers
117f and
117g transmit the amplified signals to the delay measurement unit
118. The processing unit
119 estimates three-dimensional coordinates of the position of each of the speakers
115a to
115e in accordance with a delay time measured by the delay measurement unit
118 to calculate an appropriate listening position of the user. The output signal processing
unit
121 controls a delay time of, a volume of, and a mixing ration of a signal reproduced
from each of channels to create an optimal sound field space at the appropriate listening
point or a listening point input from the listening position input unit
120, (refer to, for example, Patent Document 2).
Patent Document 1: Japanese Patent Laid-Open Publication No. 2000-354300
Patent Document 2: Japanese Patent Laid-Open Publication No. 2003-250200
Disclosure of the Invention
Problems to be solved by the Invention
[0005] Each of the conventional multi-channel audio reproduction apparatuses, however, assigns
an output channel of each of the speakers to a front-right (hereinafter, FR) speaker,
a front-left (hereinafter, FL) speaker, a front-center (hereinafter, FC) speaker,
a rear-right (hereinafter, RR) speaker, a rear-left (hereinafter, RL) speaker, and
a subwoofer (hereinafter, SW). Each of the speakers needs to be placed at the assigned
position, and to be then connected to an amplifier output corresponding to the assigned
output channel.
[0006] Consequently, the more the number of speakers, the more complicated assignments of
output channels to the speakers, and connections between the speakers and the amplifier
outputs corresponding to the output channels. As a result, the number of steps for
installing the speakers increases, and an incorrect connection may be easily occurred.
Especially, since a speaker of an in-vehicle multi-channel audio reproduction apparatus
is installed at a predetermined position in a vehicle, setting of the apparatus is
complicated and an incorrect connection may be easily occurred. This results in the
need to fix the incorrect connection.
[0007] It is, therefore, an object of the present invention is to provide a multi-channel
audio signal correction device capable of reducing the number of steps for installing
a speaker and/or an amplifier, which is/are connected to a multi-channel audio reproduction
apparatus.
Means of Solving the Problems
[0008] To accomplish the above object, the first aspect of the present invention is directed
to a multi-channel audio signal correction device. The device comprises: a measurement
signal generator for generating a measurement signal; a speaker switching section
connected to a plurality of speaker modules through a network, operable to select
one of the plurality of the speaker modules and to transmit, to the selected speaker
module, measurement signal generated by the measurement signal generator; a plurality
of sound collection units for each collecting, as a measurement sound, a sound output
from the selected speaker module in accordance with the measurement signal; a delay
measurement section operable to measure a propagation delay time of each of the measurement
sounds collected by the plurality of the sound collection units; a position estimation
section operable to estimate the position of a speaker provided in the selected speaker
module in accordance with each of the propagation delay times measured by the delay
measurement section; a channel assignment section operable to assign an output channel
to the selected speaker module in accordance with the position of the speaker, the
position being estimated by the position estimation section; and a sound field correction
section operable to generate a correction value in accordance with each of the propagation
delay times measured by the delay measurement section and with the output channel
assigned by the channel assignment section and to transmit the generated correction
value to the selected speaker module, the correction value being used to correct an
output of the selected speaker module.
[0009] The multi-channel audio signal correction device further comprises a frequency characteristic
analysis section operable to analyze a frequency characteristic of the selected speaker
module in accordance with each of the measurement sounds collected by the plurality
of the sound collection units. The channel assignment section further refers to the
frequency characteristic analyzed by the frequency characteristic analysis section
to assign an output channel to the selected speaker module. The sound field correction
section further refers to the frequency characteristic analyzed by the frequency characteristic
analysis section to generate a correction value used to correct an output of the selected
speaker module.
[0010] The multi-channel audio signal correction device further comprises a frequency range
determination section operable to determine a reproduction frequency range of the
selected speaker module in accordance with the frequency characteristic analyzed by
the frequency characteristic analysis section.. The sound field correction means further
uses the reproduction frequency range determined by the reproduction frequency range
determination section to generate a correction value used to correct an output of
the selected speaker module.
[0011] Furthermore, the reproduction frequency range determination section determines the
reproduction frequency range of the speaker provided in the selected speaker module
in accordance with the position of the speaker, the position being estimated by the
position estimation section.
[0012] The second aspect of the present invention is directed to a method for correcting
a multi-channel audio signal used in a multi-channel audio reproduction apparatus.
The method comprising steps of: generating a measurement signal; selecting one of
a plurality of speaker modules connected through a network to transmit, to the selected
speaker module, the generated measurement signal; collecting, with a plurality of
sound collection units different from each other to receive, a sound output from the
selected speaker module in accordance with the measurement signal input to the speaker
module, as a measurement sound; measuring a propagation delay time of each of the
collected sounds; estimating the position of a speaker provided in the selected speaker
module in accordance with each of the measured propagation delay times; assigning
an output channel to the selected speaker module in accordance with the estimated
position of the speaker; and generating a correction value in accordance with each
of the measured propagation delay times and with the assigned output channel, the
correction value being used to correct an output of the selected speaker module.
Effect of the Invention
[0013] According to the first and second aspects of the present invention, the position
of a speaker provided in the speaker module connected through the network is estimated
by measuring the propagation delay time of the measurement signal, and the output
channel is then automatically assigned to the selected speaker module in accordance
with the estimated position. In accordance with the measured propagation delay time
and the assigned output channel, a sound is output from an amplifier output corresponding
to the output channel automatically assigned under the condition that an audio signal
transmitted to the speaker module is corrected. This makes it possible to create a
sound environment suitable for the position of a listener. As apparent from the above
description, according to the first and second aspects of the present invention, the
output channel is automatically assigned to the selected speaker module. It is therefore
not necessary for a user to connect the speaker module to the amplifier output corresponding
to the output channel. This does not increase the number of steps for installing a
speaker or/and an amplifier, regardless of the fact that the number of speakers or/and
the number of amplifiers increase(s) with increasing the number of channels.
Brief Description of the Drawings
[0014]
Fig. 1 is a block diagram showing a multi-channel audio reproduction system according
to a first embodiment of the present invention.
Fig. 2 is a flowchart showing steps of a sound correction process performed in the
system shown in Fig. 1.
Fig. 3 is a flowchart showing detail steps included in step 13 shown in Fig. 2.
Fig. 4 is a diagram showing the configuration of a sound collection unit 34 shown
in Fig. 1.
Fig. 5 is a graph showing a method for obtaining the position of each of speakers
21a to 21e shown in Fig. 1.
Fig. 6 is a diagram showing a positional relationship between the speakers 21a to 21e and the sound collection unit 34 that is fixed to a driver seat in a vehicle.
Fig. 7 is a graph showing frequency characteristics of a speaker 21 functioning as
a super woofer shown in Fig. 1.
Figs. 8(a) to 8(d) are graphs each showing a reproduction frequency range assigned
by a frequency range determination section 38 shown in Fig. 1.
Fig. 9 is a diagram showing the position of each of the speakers, which is substantially
the same as that of a corresponding one of the speakers shown in Fig. 1.
Fig. 10 is a flowchart showing detail steps included in step S19 shown in Fig. 2.
Fig. 11 is a flowchart showing steps of a sound reproduction process performed in
the system shown in Fig. 1.
Fig. 12 is a block diagram showing an example of the configuration of a conventional
multi-channel audio reproduction apparatus.
Fig. 13 is a block diagram showing another example of the configuration of a conventional
multi-channel audio reproduction apparatus.
Description of Reference Numerals
[0015]
- 1:
- Reproduction apparatus
- 11:
- Reproduction section
- 12:
- Network driver
- 2a to
- 2e: Speaker module
- 21a to
- 21e: Speaker
- 22a to
- 22e: Power amplifier
- 23a to
- 23e: Signal processor
- 24a to
- 24e: Storage
- 25a to
- 25e: Network driver
- 3:
- Correction device
- 31:
- Speaker detection section
- 32:
- Measurement signal generator
- 33:
- Speaker switching section
- 34:
- Sound collection unit
- 35:
- Delay measurement section
- 36:
- Position estimation section
- 37:
- Frequency characteristic analysis section
- 38:
- Frequency range determination section
- 39:
- Channel assignment section
- 40:
- Target value input section
- 41:
- Sound field correction section
- 42:
- Network driver
- 4:
- Network
Best Mode for Carrying Out the Invention
[0016] Fig.
1 is a block diagram showing the configuration of a multi-channel audio reproduction
system (hereinafter merely referred to as a system) according to an embodiment of
the present invention. The system as shown in Fig.
1 is installed, for example, in a vehicle and outputs a sound in accordance with a
multi-channel audio signal. The system includes a reproduction apparatus
1, a plurality of speaker modules
2, a multi-channel audio signal correction device
3, and a network
4 connecting the reproduction apparatus
1, the speaker modules
2 and the multi-channel audio signal correction device
3, in order to output a sound. In Fig.
1, five speaker modules
2a to
2e are provided. The number of the speaker modules may be changed. Hereinafter, the
description will be made the case of the system including the speaker modules
2a to
2e.
[0017] The reproduction apparatus
1 has a reproduction section
11 and a network driver
12 to output a multi-channel audio signal to a network
4. The reproduction section
11 generates a multi-channel audio signal and outputs the signal to the network driver
12. The network driver
12 transmits the multi-channel audio signal output from the reproduction section
11 to the network
4. The multi-channel audio signal is transmitted through the network
4 to a target one of the speaker modules
2a to
2e.
[0018] The speaker modules
2a to
2e include speakers
21a to
21e, power amplifiers
22a to
22e, signal processors
23a to
23e, storages
24a to
24e, and network drivers
25a to
25e, respectively.
[0019] Each of the network drivers
25a to
25e receives a multi-channel audio signal transmitted through the network
4 from the reproduction apparatus 1 and a correction value transmitted from the multi-channel
audio signal correction device
3. The signal processors
23a to
23e are connected to the storages
24a to
24e, respectively. Each of the signal processors
23a to
23e corrects the received multi-channel audio signal in accordance with a correction
value (described in detail later) stored in a corresponding one of the storages
24a to
24e. The signal processors
23a to
23e then transmit the corrected signal to the following power amplifiers
22a to
22e, respectively. The power amplifiers
22a to
22e amplify the received multi-channel audio signal to transmit the amplified signal
to corresponding speakers
21a to
21e, respectively. Each of the speakers
21a to
21e reproduces a sound in accordance with the received multi-channel audio signal and
outputs the sound.
[0020] The multi-channel audio signal correction device
3 includes a speaker detection section
31, a measurement signal generator
32, a speaker switching section
33, a sound collection unit
34, a delay measurement section
35, a position estimation section
36, a frequency characteristic analysis section
37, a frequency range determination section
38, a channel assignment section
39, a target value input section
40, a sound field correction section
41, and a network driver
42.
[0021] The speaker detection section
31 detects the number of the speaker modules
2 connected to the network
4. The measurement signal generator
32 generates a measurement signal. The speaker switching section
33 switches a destination of a measurement signal to a speaker module to be measured.
The sound collection unit
34 exemplary includes microphones
34a to
34d, each of which is placed in a vehicle at a tip of a virtually formed equilateral tetrahedron
(refer to Fig.
4), to collect the measurement signal output from the speaker to be measured. The delay
measurement section
35 measures a propagation delay time of the measurement signal. The position estimation
section
36 estimates the position of the speaker in accordance with the measured propagation
delay time. The frequency characteristic analysis section
37 analyzes a frequency characteristic of the speaker in accordance with the collected
measurement signal. The frequency range determination section
38 determines an assignment of a reproduction frequency range to the speaker module
2 to be measured in accordance with the result of the analysis performed by the frequency
characteristic analysis section
37. The channel assignment section
39 assigns an output channel to the speaker module
2 in accordance with the result of the estimation performed by the position estimation
section
36 and with the result of the analysis performed by the frequency characteristic analysis
section
37. The target value input section
40 responds to an operation performed by a user and sets, to the sound field correction
section
41, a target characteristic value for the listening position of the user. The sound field
correction section
41 generates and sets a correction value for each of the speaker modules
2 to create a sound environment optimal for the listening position of the user. The
network driver
42 is connected to the network
4 and sends out to the network
4 the correction value generated by the sound field correction section
41. After sent out from the network driver
42, the correction value is transmitted through the network 4 to the target speaker module
2.
[0022] The network drivers
12, 25a to
25e and
42 assign a unique network ID to each device connected to the network
4. Each of the devices connected through the network
4 can obtain the type of the other device connected through the network
4 and the network ID of the other device if necessary.
[0023] Fig.
2 is a flowchart showing steps of a sound field correction process performed in the
system shown in Fig.
1. First, the target value input section
40 provided in the multi-channel audio signal correction device
3 sets a target characteristic value for the listening position of a user. Next, the
speaker detection section
31 obtains the types of all devices connected to the network 4 and detects an
N number of the speaker modules
2 (
N = 5 in the example shown in Fig.
1) in accordance with the acquired types of the devices. Then, the speaker detection
section
31 transmits data on the
N number of the speaker modules
2 to the sound field correction section
41 (Step
S11).
[0024] Next, the sound field correction section
41 sets a loop variable "
i" to "
1"(Step
S12), and then obtains information on the speaker modules
2 (Step
S13). Detailed process in the step
S13 will be described later with reference to Fig. 3. Then, the sound field correction
section
41 adds one to the loop variable "
i"(Step
S14), and then determines whether or not the variable "i" is equal to or less than the
N number of the speaker modules
2. The step
S13 described above is repeated while the variable
"i" is equal to or less than the
N number of the speaker modules
2.
[0025] Fig.
3 is a flowchart showing detail steps included in step
S13 shown in Fig.
2. As shown in Fig.
3, in the multi-channel audio signal correction device
3, the measurement signal generator
32 generates an impulse response between the speaker modules and the sound collection
unit
34, more specifically an impulse signal as an example of a measurement signal used to
obtain a propagation delay time of and a frequency characteristic of a sound output
from any one of the speakers
21(Step
S31). In the present embodiment, the impulse signal will be described as an example of
the measurement signal. An M-sequence noise and a sweep signal may be used as the
measurement signal. The impulse signal generated by the measurement signal generator
32 is transmitted through the network driver
42 and the network
4 to a target one of the speaker modules
2 which is selected by the speaker switching section
33(Step
S32).
[0026] In the target speaker module
2, the network driver
25 in the target speaker module
2 receives the impulse signal through the network
4(Step
S33), the speaker
21 receives the impulse signal through the signal processor
23 and the power amplifier
22. Then, the speaker
21 outputs a measurement sound in accordance with the received impulse signal(Step
S34).
[0027] The measurement sound output from the speaker
21 to be measured is collected by the sound collection unit
34 including the microphones
34a to
34d as shown in Fig.
4(Step
S35).
[0028] The delay measurement section
35 measures a propagation delay time of the measurement sound in accordance with the
impulse response to the measurement sound received by the sound collection unit
34. The propagation delay time measured by the delay measurement section
35 is stored in the storage
24 provided in the speaker module
2 to be measured(Step
S36).
[0029] Next, the position estimation section
36 estimates the position of the speaker
2 to be measured in accordance with the measured propagation delay time. The estimated
position of the speaker
2 is stored in the storage
24 provided in the speaker module
2 to be measured(Step
S37).
[0030] As shown in Fig. 5, the three-dimensional coordinates of the position of the speaker
2 to be measured are estimated in accordance with the arrival times
t1 to
t4 of the measurement sounds and the positions of the microphones
34a to
34d, the measurement sounds being collected by the microphones
34a to
34d provided in the sound collection unit
34.
[0031] Specifically, as shown in Fig.
4, if the three-dimensional coordinates of the microphones
34a to
34d are expressed as (
Xa,
Ya, Za), (
Xb, Yb, Zb), (
Xc,
Yc, Zc), and (
Xd, Yd, Zd), and a sonic velocity is expressed as
v, the coordinates of the position of the speaker
21 to be measured can be expressed as the following.

[0032] As shown in Fig.
6, since the sound collection unit
34 is exemplary fixed to the driver seat of the vehicle, the position of the speaker
21 to be measured can be estimated in accordance with the three-dimensional coordinates
of the sound collection unit
34 and the three-dimensional coordinates of the speaker
21 with respect to the driver seat.
[0033] The frequency characteristic analysis section
37 analyzes a frequency characteristic of the speaker
21 to be measured in accordance with the impulse response to the measurement sound received
by the sound collection unit
34. As a result, data on the frequency characteristic is transmitted through the network
4 and stored in the storage
24 provided in the speaker module
2 to be measured(Step
S38).
[0034] The abovementioned steps are performed on all the speakers
21a to
21e connected to the network
4 to obtain information on each of the speakers
21a to
21e.
[0035] Referring to Fig.
2 again, the channel assignment section
39 assigns output channels such as an FR channel, FL channel, FC channel, RR channel
and RL channel to the speakers
21a to
21e in accordance with the estimated positions of the speakers
21a to
21e. Each of the assigned output channels is transmitted through the network
4 and stored in the storage
24 corresponding to each of the speaker modules
2 (step
S16).
[0036] In a 5.1 channel system or the like, the channel assignment section
39 assigns an output channel for a super woofer to any one of the speakers
21a to
21e in accordance with frequency characteristics of the speakers
21a to
21e, the frequency characteristics being analyzed by the frequency characteristic analysis
section
37. For example, if the frequency characteristics includes a low frequency output as
shown in Fig. 7, the super woofer (SW) is assigned to a speaker providing the low
frequency output as an output channel.
[0037] Next, the frequency range determination section
38 assigns a reproduction frequency range such as a high frequency range, a middle frequency
range, and a low frequency range to each of the speakers
21a to
21e in accordance with the frequency characteristic of and the position of each of the
speakers
21a to
21e. The frequency range determination section
38 then transmits data on the assigned reproduction frequency range is transmitted through
the network
4, and the transmitted data is stored in a corresponding one of the storages
24a to
24e.
[0038] The reproduction frequency range is determined in accordance with the frequency characteristic
of the speaker
21 as illustrated in a graph of Fig.
8(a) showing frequencies divided into three ranges, i.e., a low frequency range, a middle
frequency range and a high frequency range.
[0039] As shown in Fig.
8(b), the low frequency range is assigned as the reproduction frequency range if frequencies
of an output of the speaker
21 cover the low frequency range. As shown in Fig.
8(c), the middle frequency range is assigned as the reproduction frequency range if frequencies
of the output of the speaker
21 cover the middle frequency range. As shown in Fig.
8(d), the high frequency range is assigned as the reproduction frequency range if frequencies
of the output of the speaker
21 cover the high frequency range.
[0040] The frequency range determination section
38 determines a reproduction frequency range based also on the vertical position of
the speaker
21. As shown in Fig.
9, if three speakers
21 are arranged adjacently to each other and at substantially the same position, the
frequency range determination section
38 assigns the high, middle, low frequency ranges to the speakers
21 placed at the highest, middle, lowest position, respectively.
[0041] Next, the sound field correction section
41 performs a parameter correction process on each of the speakers
21a to
21e in accordance with the target characteristic value for the listening position of
a user. More specifically, the sound field correction section
41 sets the loop variable "i" to "1"(Step
S18), and then corrects the parameter described later with reference to Fig.
10(Step
S19). Then, the sound field correction section
41 adds one to the variable
"i" (Step
S20), and then determines whether or not the variable "i" is equal to or less than the
N number of the speakers(Step
S21). The step
S19 is repeated while the variable
"i" is equal to or less than the
N number of the speakers.
[0042] Fig.
10 is a flowchart showing detail steps included in step
S19 shown in Fig.
2. The sound field correction section
41 calculates a correction value for correcting the propagation delay time of an output
from the speaker
21 to match the propagation delay time with the set target characteristic value in accordance
with the propagation delay time of an output from the speaker
21 to be corrected. The correction value for correcting the propagation delay time is
transmitted through the network
4 and stored in the storage
24 provided in the speaker module
2 to be corrected (Step
S41).
[0043] The sound field correction section
41 calculates a correction value for adjusting an equalizer to match the set target
characteristic value in accordance with a frequency characteristic of, a reproduction
frequency range of, and a channel assigned to the speaker to be corrected. The correction
value for adjusting the equalizer is transmitted through the network
4 and stored in the storage
24 provided in the speaker module
2 to be corrected(Step
S42).
[0044] In addition, the sound field correction section
41 calculates a correction value for adjusting a phase characteristic of the speaker
21 to be corrected to match the phase characteristic with the set target characteristic
value, the phase characteristic being obtained at the listening position of a user.
The correction value for adjusting the phase characteristic is transmitted through
the network
4 and stored in the storage
24 provided in the speaker module to be corrected(Step
S43).
[0045] If the correction values used for all the speakers
21 are set in the abovementioned steps, and the system reproduces a sound, the reproduction
section
11 of the reproduction apparatus
1 transmits a multi-channel audio signal to each of the speaker modules
2a to
2e through the network driver
12 and the network
4 (Step
S51).
[0046] Each of the network drivers
25a to
25e receives the multi-channel audio signal through the network
4. The signal processors
23a to
23e process the multi-channel audio signal in accordance with the data on the output
channel and the correction value that are stored in the storages
24a to
24e, respectively(Step
S52). The signal processors
23a to
23e then transmit the processed multi-channel audio signal to the speakers
21a to
21e through the power amplifiers
22a to
22e, respectively(Step
S53). Each of the speakers
21a to
21e then reproduces a sound in accordance with the processed multi-channel audio signal
to output the sound to a user.
[0047] In the system according to the present embodiment as described above, the multi-channel
audio signal correction device
3 uses the measurement signal to estimate the position of each of the speakers
21a to
21e which are arbitrarily arranged and automatically assigns an output channel to each
of the speakers
21a to
21e in accordance with the estimated position. Each of the storages
24a to
24e then stores the output channel. Each of the signal processors
23a to
23e processes the multi-channel audio signal transmitted through the network
4 in accordance with the output channel stored in the storages
24a to
24e to output the processed signal, respectively. Accordingly, the output channel is
automatically assigned to each of the speakers
21a to
21e on the basis of the position of each of the speakers
21a to
21e. Each of the speakers
21a to
21e outputs a sound in accordance with the assigned output channel. It is therefore not
necessary that the user connect a speaker to an amplifier output corresponding to
the output channel assigned in accordance with the position of the speaker. This does
not increase the number of steps for installing a speaker and/or an amplifier, although
the number of speakers and/or the number of amplifiers increase(s) with increasing
the number of channels.
[0048] The multi-channel audio signal correction device
3 analyses the frequency characteristic of the target speaker module by using the measurement
signal. The multi-channel audio signal correction device
3 then assigns a reproduction frequency range suitable for each of the speakers
21a to
21e in accordance with the analyzed frequency characteristic, resulting in an improvement
of a sound environment.
[0049] In addition, the multi-channel audio signal correction device
3 performs the parameter correction process to match with the target characteristic
value for the listening position of a user, the target characteristic value being
set by the target value input section
40. This makes it possible to form a sound environment suitable for the position of the
listener.
[0050] The network
4 is described above as a ring type in the present embodiment. The network
4, however, may be of a star type and a bus type. Also, the network
4 may be wireless.
[0051] The system with the five speakers
21 and the five speaker modules
2 is described above in the present embodiment. The number of the speakers
21 and the number of the speaker modules
2 may be four or six, or more.
[0052] The sound collection unit
34 includes the four microphones
34a to
34d, and the position estimation section
36 estimates the three-dimensional coordinates of the position of each of the speakers
21 in the present embodiment. The sound collection unit
34 may include three microphones, and the position estimation section
36 may estimate the two-dimensional coordinates of the position of each of the speakers
21. In addition, the sound collection unit
34 may include five or more microphones, and the position estimation section
36 may estimate the two or three-dimensional coordinates of the position of each of
the speakers.
[0053] The system according to the present embodiment is installed in a vehicle, but may
be installed in a house or an office.
Industrial Applicability
[0054] The multi-channel audio signal correction device according to the present invention
makes it possible to prevent an increase in the number of steps for installing a speaker
and/or an amplifier which are/is adapted to reproduce and output a sound obtained
based on the multi-channel audio signal. The multi-channel audio signal correction
device according to the present invention is suitable for a multi-channel audio reproduction
apparatus installed in a vehicle.