JP2005106880

Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2005106880
PROBLEM TO BE SOLVED: To provide a sound field correction device for improving localization
and presence of sound at a listening point. SOLUTION: A sound field correction device 1 outputs
a pulse signal as an output sound signal 9 separately to a plurality of speakers 11, and a pseudo
noise obtained by sampling the sound output from each speaker 11 at a listening point. Based on
the signal 13, the correlation operation unit 2 that calculates the impulse response from the
speaker 11 to the listening point, the average delay time operation unit 3 that calculates the
average delay time of the impulse response, and the average delay time operation unit 3 A delay
unit for delaying the input sound signal 8 from the outside based on the average delay time of
the impulse response and outputting the delayed signal to the speakers 11 as the output sound
signal 9 is provided. [Selected figure] Figure 1
Sound field correction device
[0001]
The present invention relates to a sound field correction apparatus, and more particularly to a
sound field correction apparatus that delays input signals of speakers and allows sounds from
the speakers at a listening point to be heard almost simultaneously.
[0002]
When the speakers are arranged symmetrically with respect to the listening point at a place
where the reflected wave (reflected sound) hardly occurs, the sounds outputted from the
speakers can be heard at the listening point almost at the same time, and a sense of localization
or Realism is obtained.
09-05-2019
1
[0003]
However, when sound is generated from a speaker in a closed narrow space of a vehicle
compartment using an acoustic device mounted on a vehicle, a plurality of short reflected waves
(reflected sound) are generated, and The reflected waves interfere with each other, the sound
transfer characteristic at the listening point becomes complicated, and the localization and
presence of the sound deteriorate.
Furthermore, in the case where the position of each speaker is asymmetric with respect to the
listening point, the transfer characteristic of the sound becomes more complicated, leading to
further deterioration of the localization and presence of the sound.
[0004]
As a method of correcting the propagation characteristics of sound from each speaker to the
listening point when the position of each speaker and listening point is asymmetrical in such a
narrow space enclosed in the vehicle compartment, each speaker at the listening point There is
known a method called time alignment in which a signal output to a speaker is delayed in
advance so that sounds from the speaker can simultaneously arrive.
The delay time in this method called time alignment may be set by setting the delay time to the
output sound signal input to each speaker based on the distance between each speaker and the
listening point, or from each speaker to the listening point Calculates the impulse response up to
and sets the delay time to the output sound signal input to each speaker based on the arrival
time of the sound wave that arrives first, and calculates the impulse response from each speaker
to the listening point It is known to set a delay time to an output sound signal input to each
speaker based on the maximum sound pressure value (peak value) (see Patent Document 1). JPA-10-161667
[0005]
However, in the conventional configuration, in addition to the asymmetry of the position between
each speaker and the listening point, a shield may be present between the speaker and the
09-05-2019
2
listening point depending on the listening point and the installation position of the speaker (For
example, if the driver's seat is at the listening point and the speaker is located at the bottom of
the rear door, the driver's seat and the passenger's seat shield the sound waves). In the
calculation result of the impulse response in this case, the reflected wave may be relatively larger
than the first arriving sound wave, and the reflected wave may be the dominant sound wave.
[0006]
In such a case, when the delay time is set to the output sound signal input to each speaker based
on the distance between each speaker and the listening point, this set value and the dominant
sound wave that actually arrives (reflection Because the difference with the wave increases, the
sound from each speaker does not reach the listening point at the same time audibly, and the
sense of localization and the presence of the sound deteriorate.
[0007]
In addition, when the delay time is set to the output sound signal input to each speaker based on
the arrival time of the sound wave that arrives first by computing the impulse response from
each speaker to the listening point, it is dominant Since the sound wave is a reflected wave, the
sound from each speaker does not audibly reach simultaneously.
[0008]
Furthermore, when the impulse response from each speaker to the listening point is calculated
and the delay time is set to the output sound signal input to each speaker based on the maximum
sound pressure value (peak value), it is dominant There are multiple sound waves, and the peak
value in the impulse response will arrive with a considerable delay, and the difference between
the set value of the delay time and the dominant sound wave that actually arrives will increase,
so the sound from each speaker audibly But the sound localization and presence will be
degraded.
[0009]
Therefore, an object of the present invention is to provide a sound field correction apparatus
which solves the problems of the above-described conventional techniques and aims to improve
localization and presence of sound at a listening point.
[0010]
In order to achieve the above object, the sound field correction apparatus separately outputs a
pulse signal as an output sound signal to a plurality of speakers, and a pseudo noise signal
09-05-2019
3
obtained by sampling the sound output from each speaker at a listening point A correlation
operation unit that calculates an impulse response from the speaker to the listening point, an
average delay time operation unit that calculates an average delay time of the impulse response,
and the average delay time operation unit, based on And a delay unit for delaying the input
sound signal from the outside based on the average delay time of the impulse response and
outputting the signal as an output sound signal to each of the speakers.
[0011]
In this case, a storage unit for storing an average delay time of impulse responses corresponding
to each of the speakers is provided, and the delay unit is configured to store the respective
speakers based on the average delay time of each of the impulse responses stored in the storage
unit. The input sound signal corresponding to each may be delayed.
[0012]
Further, the delay unit is configured to set an input sound signal corresponding to each speaker,
the maximum value of the average delay time, and each average delay time with reference to a
maximum value among average delay times of impulse responses corresponding to the
respective speakers. It may be delayed by a time corresponding to the difference of.
[0013]
Furthermore, the average delay time calculation unit may calculate the average delay time ad of
the impulse response according to equation (1).
[0014]
Here, fs is the sampling rate of the impulse response, t is the sampling number, Pt is the power
value of the impulse response at each sampling number, and n is the maximum value of the
sampling number.
[0015]
Furthermore, the delay unit calculates a difference between the maximum value of the average
delay times and each average delay time, and the maximum value of the average delay times
calculated by the control unit and each average delay time And the delay processing unit may be
stored as a delay setting value.
[0016]
09-05-2019
4
In this case, the delay processing unit may store the delay setting value of each of the speakers
corresponding to a plurality of listening points as a delay setting value group in association with
each of the listening points.
[0017]
Further, the acoustic device is disposed at the listening point, the sound field correction device,
the audio device for generating the input sound signal, a plurality of speakers for inputting the
output sound signal, and the sound output from the speaker You may make it provide with the
microphone to detect.
[0018]
In this case, the acoustic device may be mounted on a vehicle.
[0019]
According to the present invention, the sounds output from the speakers reach the listening
point almost at the same time aurally, and the localization and the realism of the sounds can be
improved.
[0020]
Hereinafter, an embodiment of the present invention will be described with reference to the
drawings.
[0021]
FIG. 1 is a view showing the configuration of the acoustic device 20 in the present embodiment.
As shown in FIG. 1, the acoustic device 20 includes a sound field correction device 1, a
microphone 10 installed at a listening point, and a speaker 11 for outputting an output sound
signal 9 output from the sound field correction device 1 as sound. An audio device 15 is provided
which converts music data such as a CD or MD into an input sound signal 8 and inputs the sound
signal 8 to the sound field correction device 1.
The audio device 15 converts sound of a radio, a TV or the like into the input sound signal 8 in
09-05-2019
5
addition to music data of a CD, MD or the like.
[0022]
The speaker 11 has a plurality of speakers, and is disposed, for example, at a door of a vehicle.
In this embodiment, the driver's seat door speaker 11a, the passenger seat door speaker 11b, the
rear right door speaker 11c, the rear left door speaker 11d, and four speakers are provided.
The number of speakers 11 is not limited to four. For example, it is possible to add a speaker to
the back side of the rear seat or the like, or to not provide the rear door speakers 11c and 11d.
[0023]
The sound field correction apparatus 1 includes a control unit 6, and is controlled by the control
unit 6. The correlation operation unit 2 which calculates an impulse response, and an average
delay time operation unit which calculates an average delay time of the calculated impulse
response 3, a storage unit 4 for storing the calculated value of the average delay time, a signal
generation unit 5 for generating a pulse signal 12 to be input to the speaker 11 at the time of
calculation of impulse response, and output from each speaker at a listening point And a delay
processing unit 7 for delaying the input sound signal 8 corresponding to each speaker so that the
audio sound can be heard almost simultaneously.
In the sound field correction device 1, a control unit 6 and a delay processing unit 7 constitute a
delay unit.
[0024]
FIG. 2 is a flowchart showing delay time setting processing in the present embodiment.
The delay time setting process is controlled by the control unit 6.
09-05-2019
6
[0025]
When this delay time setting process is started, the control unit 6 sends a measurement start
signal to the signal generation unit 5, and the signal generation unit 5 that has received this
measurement start signal generates a pulse signal 12 using an M-sequence code. The delay
processing unit 7 generates a sound wave (sound) through the speaker 11 (step S1).
Here, at the start of measurement, the delay time for each pulse signal 12 set in the delay
processing unit 7 is zero.
[0026]
Next, the correlation calculation unit 2 calculates the correlation between the pseudo noise signal
13 detected by the microphone 10 and the pulse signal 12 generated by the signal generation
unit 5, and the propagation characteristic of the sound wave in the vehicle compartment, ie, the
impulse response An operation is performed (step S2).
The sampling speed fs of the pseudo noise signal 13 at this time is, for example, 44.1 kHz (about
20 kHz bandwidth) in consideration of the sound wave band.
[0027]
Next, the average delay time calculator 3 calculates an average delay time ad of the impulse
response based on the impulse response calculated in the process of step S2 (step S3).
This average delay time ad [sec] is calculated by equation (1).
[0028]
Here, t is a sampling number, fs is a sampling rate (frequency), and Pt (t = 0, 1, 2, 3 ... n) is the
power value of impulse response at each sampling number (= sound pressure T = 0 is the
09-05-2019
7
sampling start point (start point of the pulse signal 12) of the pseudo noise signal 13, and t = n is
the sampling end point of the pseudo noise signal 13.
[0029]
For example, when there are a plurality of dominant sound waves as shown in FIG. 3, the
calculation result of the impulse response calculated in the process of step S2 is the barycenter
of each impulse response, that is, the average delay of the impulse response By calculating the
time and delaying each input sound signal 8 in the delay processing unit 7 described later, it is
possible to hear sounds output from the speaker 11 almost at the same time aurally.
[0030]
The storage unit 4 stores the average delay time of the impulse response calculated in the
process of step S3 in association with the speakers 11a to 11d (step S4).
For example, as shown in FIG. 4, the average delay time of the impulse response in the driver's
door door speaker 11a is stored as 0.00885 [sec], and the average delay time of the impulse
response in the passenger's door door speaker 11b is 0.00782 [sec] ] Is memorized.
[0031]
Next, the control unit 6 determines whether the calculation processing of the average delay time
of the impulse response has been performed for all the speakers (step S5).
If the calculation processing of the average delay time of the impulse response has not been
completed for all the speakers (step S5; No), the process proceeds to step S1, and the processing
of steps S1 to S4 is performed for each speaker.
When the calculation processing of the average delay time of the impulse response is completed
for all the speakers (step S5; Yes), the processing shifts to the next processing.
[0032]
09-05-2019
8
Next, the control unit 6 determines whether to calculate the delay setting value using the average
delay time of the impulse response stored in the process of step S4 to the user (step S5).
Here, when the delay setting value is not calculated, for example, when the user changes the
arrangement position of the microphone, a sound from other than the speaker is input to the
microphone when changing the listening point or during this delay time setting processing. The
user may feel that the delay time setting process is not performed correctly.
[0033]
If the delay setting value is not calculated in the determination of step S5 (step S5; No), the
process proceeds to step S1, and the processes of step S1 to step S4 are performed again for
each speaker.
[0034]
When the delay setting value is set in the delay processing unit 7 using the average delay time of
the impulse response stored in the process of step S4 in the determination of step S5 (step S5;
Yes), the control unit 6 The difference is set as the delay setting value in the delay processing
unit 7 based on the maximum value of the average delay time of the impulse response stored in
4 (step S7), and the delay time setting process is ended.
[0035]
In the present embodiment, the control unit 6 functions as a delay calculation unit, and the delay
setting value is calculated by the delay calculation unit.
As shown in FIG. 4, since the average delay time of the rear left door speaker 11 d is 0.01181
[sec] with the maximum value of the average delay time of the impulse response, the difference
between the driver's door door speaker 11 a is based on this value. Becomes 0.01181−0.00885
= 0.00296 [sec], and 0.00296 [sec] is stored and set in the delay processing unit 7 as the delay
setting value of the driver's seat door speaker 11a.
The delay processing unit 7 delays the input sound signal 8 corresponding to each speaker by
09-05-2019
9
the time of the set delay setting value.
[0036]
In the delay time setting process described above, the average delay time of the impulse response
is also calculated by the simple method of calculating the gravity center of each impulse
response, that is, the average delay time of the impulse response by the average delay time
calculation unit 3 using equation (1). The input sound signal 8 corresponding to each speaker
can be delayed so that the sound from each speaker at the listening point can reach almost
simultaneously.
As a result, when the sound field correction apparatus 1 reproduces music etc., the sound from
each speaker will be heard almost at the same time audibly at the listening point, and the
localization of the sound and the realism will be improved. Can.
[0037]
Although one microphone 10 is used in this embodiment, a plurality of microphones may be
used to have a plurality of listening points, and the delay setting value of each speaker at each
listening point may be stored and set in the delay processing unit 7.
For example, when the microphones 10 are arranged in the driver's seat and the passenger's
seat, and the driver's seat is used as a listening point, the delay setting value of each speaker is
set to the delay processing unit 7 as a first delay setting value group corresponding to the
listening point. When storing the delay setting value of each speaker at the time when the front
passenger seat is used as a listening point next time is stored in the delay processing unit 7 as a
second delay setting value group corresponding to the listening point, and music and the like are
reproduced In this case, the delay time setting process is executed again even when the listening
point is changed by performing a process of calling the stored first delay setting value group or
the second delay setting value group from the delay processing unit 7. There is no need.
[0038]
In this case, when the listening point is changed after the process of step S7, the listening point is
changed and the processes of steps S1 to S7 are performed to calculate the delay setting value
09-05-2019
10
for each speaker corresponding to the changed listening point. Then, a step of storing the delay
setting value group corresponding to the calculated listening point in the delay processing unit 7
is added.
[0039]
Moreover, although the sound field correction ¦ amendment apparatus 1 of this embodiment is
mounted in the vehicle, you may use it in the place which the reflected wave generate ¦ occur ¦
produces indoors etc. besides a vehicle.
Furthermore, the reflected wave is relatively larger than the first arriving sound wave, and the
effect can be obtained by using it in a place where a plurality of dominant sound waves are
generated.
[0040]
The present embodiment is merely an aspect of the present invention, and can be arbitrarily
modified within the scope of the present invention.
[0041]
Fig. 1 shows an embodiment of an acoustic device according to the invention.
It is a figure which shows the delay time setting flow by this invention.
It is a figure which shows the example of an impulse response in a vehicle interior.
It is a figure which shows the example of delay time setting by this invention.
Explanation of sign
09-05-2019
11
[0042]
Reference Signs List 1 sound field correction device 2 correlation calculation unit 3 average
delay time calculation unit 4 storage unit 5 signal generation unit 6 control unit (delay
calculation unit, delay unit) 7 delay processing unit (delay unit) 10 microphone 11 speaker 15
audio device 20 acoustic apparatus
09-05-2019
12