JP6753698B2 - Propagation delay time calculation device, playback device, propagation delay time calculation system and propagation delay time calculation program - Google Patents

Description

The present invention relates to a propagation delay time calculation device, a reproduction device, a propagation delay time calculation system, and a propagation delay time calculation program.

Generally, speakers are installed at a plurality of positions in the vehicle interior. For example, the left front speaker and the right front speaker are installed at positions symmetrical with respect to the center line of the passenger compartment space. However, these speakers are not in symmetrical positions when the listener's listening position (driver's seat, passenger's seat, rear seat, etc.) is considered as a reference. Therefore, due to the difference in distance between the listener's listening position and each of the plurality of speakers (the difference in the time it takes for the reproduced sound emitted from each speaker to reach), the sound image localization is biased due to the Haas effect and the sense of presence is reduced. appear.

As a process for improving the bias of the sound image localization and the decrease in the sense of presence, a time alignment process for adjusting the time so that the measurement signal output from each speaker reaches the listening position of the listener at the same time is known. In the time alignment process, the impulse response characteristic between each speaker and the listening position is measured using the measurement signal, and the sound propagation delay time between each speaker and the listening position is obtained based on the measured impulse response characteristic. ..

Generally, in the measurement of impulse response characteristics, a loop configuration is required in order to synchronize the time between the reproduction system that reproduces the measurement signal and the recording system that records the measurement signal. However, the playback system and the recording system may not form a loop. Illustratively, an in-vehicle device (reproduction device) having no external input is used as the reproduction system, and a recording device different from the reproduction device such as a smartphone is used as the recording system. In this case, since the playback system and the recording system cannot be time-synchronized, it is difficult to accurately obtain the sound propagation delay time between each speaker and the listening position.

Therefore, for example, Patent Document 1 and Patent Document 2 describe a specific method for measuring impulse response characteristics in a system in which the reproduction system and the recording system do not have a loop configuration. However, in any of the methods described in the patent documents, the time is not synchronized between the reproduction system and the recording system in the measurement of the impulse response characteristic, and the sound propagation delay time between each speaker and the listening position must be obtained accurately. Is difficult.

JP-A-2002-365320 Japanese Unexamined Patent Publication No. 2011-22555

The present invention has been made in view of the above circumstances, and an object of the present invention is suitable for obtaining the sound propagation delay time between each speaker and the listening position based on the impulse response characteristics measured asynchronously. It is to provide a propagation delay time calculation device, a reproduction device, a propagation delay time calculation system, and a propagation delay time calculation program.

The propagation delay time calculation device according to the embodiment of the present invention includes measurement signals for each speaker that are time-non-interfering output from each of the plurality of speakers, and all speakers simultaneously output from all of the plurality of speakers. Recording means for recording the measurement signal of the above at a predetermined listening position, impulse response characteristic calculation means for calculating the impulse response characteristic of the recorded measurement signal, and measurement of the calculated measurement signal for each speaker and all speakers. A calculation means for calculating the mutual correlation of the impulse response characteristics with the signal for use, and a propagation delay time for calculating the propagation delay time of the measurement signal between each of the plurality of speakers and the listening position based on the calculated result of the mutual correlation. It is equipped with a calculation means.

Further, the propagation delay time calculation device according to the embodiment of the present invention flatly corrects the frequency characteristic of the impulse response of the measurement signal for each speaker, and measures the correction coefficient used when correcting the frequency characteristic. The configuration may include a transfer means for transferring the signal to a reproduction device that reproduces the signal. In this case, the recording means records the measurement signals of all the speakers, which are corrected by the correction coefficient by the reproduction device and simultaneously output from all of the plurality of speakers, at the listening position.

Further, in one embodiment of the present invention, the calculation means time-offs the impulse response characteristic of the measurement signal for each speaker so that the maximum amplitude matches the reference position on the time axis, and the measurement signal of all the speakers. The impulse response characteristic may be time-offset so that the maximum amplitude matches the reference position, and then the cross-correlation is calculated.

Further, the propagation delay time calculation device according to the embodiment of the present invention may be configured to include band limiting means for band limiting the impulse response characteristics of the measurement signals of each speaker or all speakers. In this case, the calculation means calculates the cross-correlation between the impulse response characteristic of one measurement signal for each speaker and all the speakers and the impulse response characteristic of the other measurement signal whose band is limited.

Further, the propagation delay time calculation device according to the embodiment of the present invention may be configured to include means for transferring the propagation delay time calculated by the propagation delay time calculation means to the reproduction device.

Further, the reproduction device according to the embodiment of the present invention is a device capable of communicating with the propagation delay time calculation device, and sequentially outputs measurement signals from each of the plurality of speakers at timings that do not interfere with each other in time. Time alignment processing is performed using the means, the means for simultaneously outputting measurement signals from all of a plurality of speakers, the means for receiving the propagation delay time transferred from the propagation delay time calculator, and the received propagation delay time. Provide means to do.

Further, the propagation delay time calculation system according to the embodiment of the present invention includes a reproduction device and a propagation delay time calculation device. The playback device sequentially outputs measurement signals from each of the plurality of speakers at timings that do not interfere with each other in time. The propagation delay time calculation device records the measurement signal for each speaker at a predetermined listening position, and calculates the impulse response characteristic of the recorded measurement signal for each speaker. Further, the playback device simultaneously outputs measurement signals from all of the plurality of speakers. The propagation delay time calculation device records the measurement signals output from all the speakers at the same time at the listening position, calculates the impulse response characteristics of the recorded measurement signals of all the speakers, and calculates the measurement signals for each speaker. The mutual correlation of the impulse response characteristics between the speaker and the measurement signals of all the speakers is calculated, and the propagation delay time of the measurement signal between each of the plurality of speakers and the listening position is calculated based on the calculated mutual correlation result.

Further, in one embodiment of the present invention, the propagation delay time calculation device flatly corrects the frequency characteristic of the impulse response of the measurement signal for each speaker, and transfers the correction coefficient used at the time of correcting the frequency characteristic to the reproduction device. It may be configured. In this case, the reproduction device corrects the measurement signal with a correction coefficient, and simultaneously outputs the corrected measurement signal from all of the plurality of speakers.

Further, in one embodiment of the present invention, the propagation delay time calculation device time-offs the impulse response characteristic of the measurement signal for each speaker so that the maximum amplitude matches the reference position on the time axis, and measures all the speakers. The impulse response characteristic of the signal for use may be time-offset so that the maximum amplitude matches the reference position, and then the cross-correlation is calculated.

Further, in one embodiment of the present invention, the propagation delay time calculation device band-limits the impulse response characteristics of the measurement signals of each speaker or all speakers, and the impulse response characteristics of one of the measurement signals of each speaker and all speakers. And may be configured to calculate the mutual correlation with the impulse response characteristic of the other band-limited measurement signal.

Further, in one embodiment of the present invention, the propagation delay time calculation device may be configured to transfer the calculated propagation delay time to the reproduction device. In this case, the reproduction device receives the propagation delay time transferred from the carrier delay time calculation device, and performs the time alignment process using the received propagation delay time.

Further, the propagation delay time calculation program according to the embodiment of the present invention is a first recording that records measurement signals for each speaker that are output from each of a plurality of speakers and that do not interfere with each other at a predetermined listening position. A step, a first impulse response characteristic calculation step for calculating the impulse response characteristic of the measurement signal for each recorded speaker, and a second recording step for recording the measurement signal simultaneously output from all the speakers at the listening position. And the second impulse response characteristic calculation step for calculating the impulse response characteristics of the recorded measurement signals of all speakers, and the impulse response characteristics of the calculated measurement signals for each speaker and the measurement signals of all speakers. The computer executes a calculation step for calculating the mutual correlation and a propagation delay time calculation step for calculating the propagation delay time of the measurement signal between each of the plurality of speakers and the listening position based on the calculated result of the mutual correlation. It is a program to make it.

According to one embodiment of the present invention, a propagation delay time calculation device, a reproduction device, and a propagation delay suitable for obtaining a sound propagation delay time between each speaker and a listening position based on an impulse response characteristic measured asynchronously. A time calculation system and a propagation delay time calculation program are provided.

It is a block diagram which shows the structure of the acoustic system which concerns on one Embodiment of this invention. It is a figure which shows the sequence of the propagation delay time calculation processing executed in the acoustic system which concerns on one Embodiment of this invention. It is a figure which shows the impulse response characteristic calculated in the process step S13 of FIG. It is a figure which shows each amplitude spectrum after the Fourier transform executed in the processing step S14 of FIG. 2, the smoothing processing, and the inverse filtering processing. It is a figure which shows each amplitude spectrum before and after the equalizer correction executed in the process step S14 of FIG. It is a figure which shows the impulse response characteristic after the inverse Fourier transform executed in the processing step S15 of FIG. It is a figure which shows the impulse response characteristic after the time offset executed in the process step S17 of FIG. It is a figure which shows the impulse response characteristic and the frequency characteristic thereof time offset in the process step S23 of FIG. It is a figure which shows the cross-correlation characteristic (similarity) obtained as a result of execution of the processing step S24 of FIG. It is a figure which shows the cross-correlation characteristic obtained as a result of execution of the processing step S24 when the equalizer correction is not performed in the processing step S14 of FIG. It is a figure which shows the amplitude spectrum after the equalizer correction by the processing step S14 of FIG. 2 band-limited to 300Hz-8kHz. It is a figure which shows the cross-correlation characteristic obtained as a result of execution of the processing step S24 when the band limitation shown in FIG. 11 is performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, an acoustic system will be described as an example of an embodiment of the present invention.

[Configuration of sound system 1]
FIG. 1 is a block diagram showing a configuration of an acoustic system 1 according to an embodiment of the present invention. The sound system 1 according to the present embodiment includes a playback device 10 and a recording device 20.

The playback device 10 is, for example, an in-vehicle audio device mounted on a vehicle, and decodes a measurement signal input from a sound source such as a CD (Compact Disc) or a DVD (Digital Versatile Disc) to decode each speaker in the vehicle interior. A measurement signal is output from FL, FR, RL, and RR. The speakers FL, FR, RL, and RR are embedded in the front left door, the front right door, the rear left door, and the rear right door, respectively. As the measurement signal, an M-sequence signal (Maximum Length Sequence), which is pseudo-random noise, is used.

The recording device 20 is a portable terminal that can be brought into the vehicle interior, such as a smartphone, a feature phone, a PHS (Personal Handy phone System), a tablet terminal, a notebook PC, a PDA (Personal Digital Assistant), a PND (Portable Navigation Device), and a portable game machine. As shown in FIG. 1, it has a recording unit 21, an impulse response calculation unit 22, an equalizer correction unit 23, an offset unit 24, and a propagation delay time calculation unit 25.

The recording device 20 calculates the propagation delay time of the measurement sound (measurement signal) between each speaker FL, FR, RL, RR and the listening position required for the time alignment process in cooperation with the playback device 10. The playback device 10 outputs music or the like time-aligned with the propagation delay time calculated by the recording device 20 from each speaker. As a result, the listener can listen to the music or the like in an environment in which the bias of the sound image localization due to the Haas effect and the decrease in the sense of presence are suppressed.

[Propagation delay time calculation processing]
FIG. 2 is a diagram showing a sequence of propagation delay time calculation processing executed in collaboration with the reproduction device 10 and the recording device 20 according to the embodiment of the present invention. This sequence is started when, for example, a listener performs a transition operation to a mode for executing the propagation delay time calculation process.

[S11 in FIG. 2 (output of measurement signal)]
In this processing step S11, the reproduction device 10 sequentially outputs measurement signals from the speakers FL, FR, RL, and RR. Each measurement signal is sequentially output at regular time intervals so as not to interfere with time.

[S12 in FIG. 2 (recording of measurement signal)]
In this processing step S12, the recording unit 21 records measurement signals from each speaker sequentially input to the microphone attached to the recording device 20 or the built-in microphone. In this embodiment, the position of the microphone is the listening position. The listener can arbitrarily determine the listening position by arbitrarily placing the recording device 20 in the vehicle interior such as the driver's seat and the passenger's seat.

[S13 (calculation of impulse response characteristics) in FIG. 2]
In the present processing step S13, the impulse response calculation unit 22 includes the measurement signal (hereinafter, referred to as “recorded signal”) and the reference signal from each speaker recorded in the processing step S12 (recording of the measurement signal). The mutual correlation function of is obtained by calculation, and the impulse response characteristic is calculated. Supplementally, in the present embodiment, since the playback device 10 and the recording device 20 do not have a loop configuration, an asynchronous impulse response characteristic is calculated. The reference signal is an M-sequence signal that is the same as the measurement signal output from the reproduction device 10, and is stored in advance in the recording device 20. Hereinafter, for convenience of explanation, the impulse response characteristics of the measurement signal between each speaker FL, FR, RL, RR and the listening position will be referred to as impulse response characteristics FL, FR, RL, and RR, respectively.

FIG. 3 illustrates the impulse response characteristics calculated in the present processing step S13. 3 (a), 3 (b), 3 (c), and 3 (d) show impulse response characteristics FL, FR, RL, and RR, respectively. In FIG. 3, the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec). In each of the figures of FIGS. 3 (a) to 3 (d), the time of maximum amplitude is set to 0 sec. The time at which the maximum amplitude is reached is the time at which the absolute value of the amplitude becomes maximum.

[S14 (equalizer correction) in FIG. 2]
In this processing step S14, the equalizer correction unit 23 performs equalizer correction. Specifically, the impulse response characteristics FL, FR, RL, and RR calculated in the processing step S13 (calculation of the impulse response characteristic) are converted into the frequency domain by the Fourier transform. Next, the amplitude spectrum obtained by the Fourier transform is smoothed and then reverse-filtered. The amplitude spectrum after the inverse filtering process is equalized and corrected so that the frequency characteristics become flat. Hereinafter, for convenience of explanation, the equalizer correction coefficient used at the time of equalizer correction of the impulse response characteristic FL is referred to as an equalizer correction coefficient FL, and the equalizer correction coefficient used at the time of equalizer correction of the impulse response characteristic FR is referred to as an equalizer correction coefficient FR. The equalizer correction coefficient used at the time of equalizer correction of the characteristic RL is referred to as an equalizer correction coefficient RL, and the equalizer correction coefficient used at the time of equalizer correction of the impulse response characteristic RR is referred to as an equalizer correction coefficient RR.

FIG. 4 exemplifies the amplitude spectrum (dotted line) after the Fourier transform, the amplitude spectrum (thin line) after the smoothing process, and the amplitude spectrum (thick line) after the inverse filtering process. 4 (a), 4 (b), 4 (c), and 4 (d) show the amplitude spectra of the impulse response characteristics FL, FR, RL, and RR after each treatment, respectively. In FIG. 4, the vertical axis indicates the level (unit: dB), and the horizontal axis indicates the frequency (unit: Hz).

Further, FIG. 5 exemplifies the amplitude spectra before the equalizer correction (thin line) and after the equalizer correction (thick line). 5 (a), 5 (b), 5 (c), and 5 (d) show the amplitude spectra of the impulse response characteristics FL, FR, RL, and RR before and after the equalizer correction, respectively. In FIG. 5, the vertical axis indicates the level (unit: dB), and the horizontal axis indicates the frequency (unit: Hz).

As shown in FIG. 5, by performing the equalizer correction, the frequency characteristic of each impulse response becomes flat, and the signal level of each impulse response characteristic is made uniform at the same level.

[S15 (inverse Fourier transform) in FIG. 2]
In this processing step S15, the equalizer correction unit 23 converts the impulse response characteristic of the frequency domain after the equalizer correction into the time domain by the inverse Fourier transform. FIG. 6 illustrates the impulse response characteristics after the inverse Fourier transform. 6 (a), 6 (b), 6 (c), and 6 (d) show the impulse response characteristics FL, FR, RL, and RR after the inverse Fourier transform, respectively. In FIG. 6, the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec).

As shown in FIG. 6, the signal levels of the impulse response characteristics FL, FR, RL, and RR are aligned to the same level by equalizer correction. As a result, it can be seen that the amplitude on the rear (speaker RL, RR) side is increased to the same extent as the amplitude on the front (speaker FL, FR) side as compared with the amplitude before the equalizer correction (see FIG. 4).

[S16 in FIG. 2 (detection of the first wave)]
In this processing step S16, the offset unit 24 detects the arrival time of the first wave for each impulse response characteristic FL, FR, RL, and RR after the inverse Fourier transform. Specifically, the impulse response characteristic after the inverse Fourier transform is converted to an absolute value. Next, the time when the amplitude of the absolute valued impulse response characteristic exceeds a predetermined threshold value is detected as the arrival time of the first wave. For the threshold value, for example, a value corresponding to the maximum amplitude of the absolute valued impulse response characteristic is set.

In the present embodiment, since the frequency characteristics are adjusted by the equalizer correction in the processing step S14 (equalizer correction), the arrival time of the first wave can be easily detected in the processing step S16 (detection of the first wave). It has become.

[S17 (time offset) in FIG. 2]
In this processing step S17, each impulse response characteristic FL, FR, RL, and RR after the inverse Fourier transform is time-offset by the offset unit 24. Specifically, each impulse response characteristic after the inverse Fourier transform is shifted on the time axis so that the arrival time of the first wave detected in the processing step S16 (detection of the first wave) becomes 0 sec. ..

FIG. 7 illustrates the impulse response characteristics FL, FR, RL, and RR after the time offset when the threshold value is -12 dB. 7 (a), 7 (b), 7 (c), and 7 (d) show impulse response characteristics FL, FR, RL, and RR after a time offset, respectively. In FIG. 7, the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec).

[S18 in FIG. 2 (transfer of equalizer correction coefficient)]
In this processing step S18, the equalizer correction coefficients FL, FR, RL, and RR used at the time of equalizer correction in processing step S14 (equalizer correction) are transferred from the recording device 20 to the playback device 10 together with a predetermined command.

[S19 in FIG. 2 (output of measurement signal)]
In this processing step S18, the playback device 10 performs equalizer correction and output of the measurement signal according to the command transferred from the recording device 20. Specifically, in the present processing step S18, the equalizer of the measurement signal is equalized by using the equalizer correction coefficients FL, FR, RL, and RR transferred in the processing step S18 (transfer of the equalizer correction coefficient) by the reproduction device 10. Correction is performed for each speaker. Next, the equalizer-corrected measurement signal, that is, the measurement signal corrected so that the frequency characteristics are flat and the signal levels are at the same level at the listening position, is simultaneously transmitted from all the speakers FL, FR, RL, and RR. It is output.

[S20 in FIG. 2 (recording of measurement signal)]
In this processing step S20, the recording unit 21 records the measurement signals from all the speakers input to the microphone.

[S21 of FIG. 2 (calculation of impulse response characteristics)]
In the present processing step S21, the impulse response calculation unit 22 obtains the cross-correlation function between the recorded signal and the reference signal recorded in the processing step S20 (recording of the measurement signal) by calculation, and all the speakers and the listening position. The impulse response characteristics of the measurement signal between are calculated. Hereinafter, for convenience of explanation, the impulse response characteristic of the measurement signal between all the speakers and the listening position will be referred to as the impulse response characteristic SP.

[S22 in FIG. 2 (detection of the first wave)]
In the present processing step S22, the offset unit 24 applies the impulse response characteristic SP calculated in the processing step S21 (calculation of the impulse response characteristic) to the first wave in the same manner as in the processing step S16 (detection of the first wave). The arrival time is detected.

[S23 (time offset) in FIG. 2]
In the present processing step S23, the impulse response characteristic SP calculated in the processing step S21 (calculation of the impulse response characteristic) by the offset unit 24 is the first wave detected in the processing step S22 (detection of the first wave). Is shifted on the time axis so that the arrival time of is 0 sec.

FIG. 8A exemplifies the impulse response characteristic SP time-offset in the processing step S23 (time offset), and FIG. 8B shows the time-offset impulse response in the processing step S23 (time offset). The frequency characteristic of the characteristic SP is illustrated. In FIG. 8A, the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec). Further, in FIG. 8B, the vertical axis indicates the level (unit: dB), and the horizontal axis indicates the frequency (unit: Hz).

[S24 (cross-correlation calculation) in FIG. 2]
In the present processing step S24, each of the impulse response characteristics FL, FR, RL, and RR time-offset in the processing step S17 (time offset) by the propagation delay time calculation unit 25 is performed in the processing step S23 (time offset). The cross-correlation with the time-offset impulse response characteristic SP is calculated. The impulse response characteristic SP of the measurement signal output from all the speakers is a combination of the impulse response characteristics of the measurement signal including the relative time difference output from each speaker. Therefore, by performing the cross-correlation calculation in the present processing step S24, a component (cross-correlation characteristic) corresponding to each speaker included in the impulse response characteristic SP can be obtained.

FIG. 9 illustrates the cross-correlation characteristics obtained as a result of the execution of the present processing step S24. FIG. 9 (a) shows the cross-correlation characteristic between the impulse response characteristic FL and the impulse response characteristic SP, and FIG. 9 (b) shows the cross-correlation characteristic between the impulse response characteristic FR and the impulse response characteristic SP. (C) shows the cross-correlation characteristic between the impulse response characteristic RL and the impulse response characteristic SP, and FIG. 9D shows the cross-correlation characteristic between the impulse response characteristic RR and the impulse response characteristic SP. In FIG. 9, the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec).

[S25 in FIG. 2 (calculation of propagation delay time)]
The difference in the peak position of the cross-correlation characteristic (in other words, the appearance position of the maximum amplitude of the impulse response characteristic) obtained in the processing step S24 (cross-correlation calculation) is the relative propagation of the measured sound between each speaker and the listening position. Corresponds to the delay time. Therefore, in the present processing step S25, the propagation delay time is calculated based on the difference in the peak positions of the cross-correlation characteristics.

In the example of FIG. 9, the impulse response characteristic FL and the impulse response characteristic SP have a peak of the cross-correlation characteristic at 2.31 msec (790 mm in terms of distance) (see FIG. 9A). Further, the impulse response characteristic FR and the impulse response characteristic SP have a peak of cross-correlation characteristic at 1.04 msec (350 mm in terms of distance) (see FIG. 9B). Further, the impulse response characteristic RL and the impulse response characteristic SP have a peak of the cross-correlation characteristic at 2.75 msec (900 mm in terms of distance) (see FIG. 9C). Further, the impulse response characteristic RR and the impulse response characteristic SP have a peak of cross-correlation characteristic at 1.52 msec (520 mm in terms of distance) (see FIG. 9D).

In the example of FIG. 9, the appearance of the peak position has the slowest impulse response characteristic RL among the impulse response characteristics FL, FR, RL, and RR. Therefore, the propagation delay time of the measured sound between each speaker and the listening position is calculated based on the peak position of the impulse response characteristic RL. Hereinafter, for convenience of explanation, the propagation delay time of the measured sound between the speaker FL and the listening position is referred to as the propagation delay time FL, the propagation delay time of the measured sound between the speaker FR and the listening position is referred to as the propagation delay time FR, and the speaker RL. The propagation delay time of the measured sound between the listening position is referred to as the propagation delay time RL, and the propagation delay time of the measured sound between the speaker RR and the listening position is referred to as the propagation delay time RR.

The specific numerical values of the propagation delay time calculated in the present processing step S25 are as follows.

Propagation delay time FL: 0.44 (= | 2.31-2.75 |) msec
Propagation delay time FR: 1.71 (= | 1.04-2.75 |) msec
Propagation delay time RL: 0.00 (= | 2.75-2.75 |) msec
Propagation delay time RR: 1.23 (= | 1.52-2.75 |) msec

Here, FIG. 10 is a diagram similar to FIG. 9, and when the equalizer correction of the processing step S14 (equalizer correction) is not performed, the cross-correlation obtained as a result of the execution of the processing step S24 (cross-correlation calculation) is obtained. The characteristics are illustrated. When the equalizer correction is not performed, as shown in FIG. 10, since the signal level on the rear (speaker RL, RR) side is small, the measurement signal output from the rear side is output from the front (speaker FL, FR). It will be masked by the measurement signal to be used. Therefore, it becomes difficult to accurately detect the peak position on the rear side. In other words, in the present embodiment, by performing the equalizer correction in the processing step S14 (equalizer correction), the peak position can be easily detected on the rear side with high accuracy. Therefore, it can be said that the equalizer correction is useful for calculating the propagation delay time with high accuracy.

[S26 in FIG. 2 (transfer of propagation delay time)]
In the present processing step S26, each propagation delay time FL, FR, RL, and RR calculated in the processing step S25 (calculation of the propagation delay time) is transferred from the recording device 20 to the reproduction device 10.

The reproduction device 10 does not accurately synchronize with the recording device 20 by using the propagation delay times FL, FR, RL, and RR obtained as a result of executing the propagation delay time calculation process of FIG. Nevertheless (based on the asynchronous impulse response characteristics), the music output from each speaker FL, FR, RL, RR, etc. can reach the listening position substantially at the same time. As a result, the listener can listen to the music or the like in an environment in which the bias of the sound image localization due to the Haas effect and the decrease in the sense of presence are suppressed.

The equalizer correction coefficients FL, FR, RL, and RR can be used to correct the frequency characteristics of the reproduced music and the like.

The above is the description of the exemplary embodiment of the present invention. The embodiments of the present invention are not limited to those described above, and various modifications can be made within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes the content obtained by appropriately combining examples and the like or obvious examples and the like specified in the specification.

For example, in another embodiment of the present invention, the propagation delay time can be calculated for a component of a specific band included in the measurement signal. FIG. 11 shows a band-limited amplitude spectrum after equalizer correction by processing step S14 (equalizer correction) to 300 Hz to 8 kHz. Further, FIG. 12 illustrates the cross-correlation characteristics obtained as a result of the execution of the processing step S24 (cross-correlation calculation) when the band limitation shown in FIG. 11 is performed. In FIG. 11, the vertical axis indicates the level (unit: dB), and the horizontal axis indicates the frequency (unit: Hz). Further, in FIG. 12, the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec).

Even when the amplitude spectrum after the equalizer correction is band-limited, there is a peak position (that is, a position where the maximum amplitude of the impulse response characteristic appears) as shown in FIG. Therefore, based on this peak position, the propagation delay time of the component of the specific band (here, 300 Hz to 8 kHz after the band limitation) can be obtained by executing the same process as that of the above embodiment. The band limitation is not limited to the impulse response characteristics FL, FR, RL, and RR after the equalizer correction in the processing step S14 (equalizer correction), and all speakers calculated in the processing step S21 (calculation of the impulse response characteristics). This may be performed for the impulse response characteristic SP of.

Further, the sound source (measurement signal) may be stored in the recording device 20 instead of the playback device 10. In this case, instead of the processing step S11 (output of the measurement signal) in FIG. 2, the recording device 20 uses Bluetooth (registered trademark), Wi-Fi, or the like to reproduce the measurement signal at regular time intervals. Transfer to 10 multiple times (for the number of speakers, 4 times in this case). As a result, the playback device 10 sequentially outputs measurement signals from the speakers FL, FR, RL, and RR at timings that do not interfere with each other in time. Further, instead of the processing step S18 (transfer of the equalizer correction coefficient) and the processing step S19 (output of the measurement signal) in FIG. 2, after the recording device 20 performs the equalizer correction, Bluetooth (registered trademark) or Wi- The measurement signals for all the equalizer-corrected speakers are collectively transferred to the playback device 10 by Fi or the like. As a result, the reproduction device 10 simultaneously outputs the measurement signals corrected so that the frequency characteristics are flat and the signal levels are the same at the listening position from all the speakers.

By equalizing the measurement signals for all speakers on the recording device 20 side, the relative propagation delay time for each speaker is calculated. Therefore, for example, even if the delay time of wireless communication changes depending on the communication environment, the time alignment process with high accuracy can be achieved without being affected by the delay time.

1 Sound system 10 Playback equipment 20 Recording equipment 21 Recording unit 22 Impulse response calculation unit 23 Equalizer correction unit 24 Offset unit 25 Propagation delay time calculation unit

Claims (7)

A recording means for recording measurement signals for each speaker that are time-non-interfering output from each of the plurality of speakers and measurement signals for all speakers that are simultaneously output from all of the plurality of speakers at a predetermined listening position. ,
Impulse response characteristic calculation means for calculating impulse response characteristics of recorded measurement signals, and
An arithmetic means for calculating the cross-correlation of the impulse response characteristics between the calculated measurement signal for each speaker and the measurement signal for all the speakers.
A propagation delay time calculating means for calculating the propagation delay time of the measurement signal between each of the plurality of speakers and the listening position based on the calculated cross-correlation result.
To prepare
Propagation delay time calculator. A correction means for flatly correcting the frequency characteristics of the impulse response of the measurement signal for each speaker, and
A transfer means for transferring the correction coefficient used for correcting the frequency characteristic to a reproduction device that reproduces the measurement signal, and
With
The recording means
The reproduction device records the measurement signals of all the speakers corrected by the correction coefficient and simultaneously output from all of the plurality of speakers at the listening position.
The propagation delay time calculation device according to claim 1. The calculation means is
The impulse response characteristics of the measurement signals for each speaker are time-offset so that the maximum amplitude matches the reference position on the time axis, and the impulse response characteristics of the measurement signals of all speakers are adjusted so that the maximum amplitude matches the reference position. After time-offset to, the above-mentioned cross-correlation is calculated.
The propagation delay time calculation device according to claim 1 or 2. A band limiting means for band limiting the impulse response characteristics of the measurement signals of each speaker or all speakers is provided.
The calculation means is
The cross-correlation between the impulse response characteristics of one measurement signal for each speaker and all the speakers and the impulse response characteristics of the band-limited other measurement signal is calculated.
The propagation delay time calculation device according to any one of claims 1 to 3. A means for transferring the propagation delay time calculated by the propagation delay time calculation means to the reproduction device is provided.
The propagation delay time calculation device according to claim 3 or 4, wherein claim 2 is cited. A propagation delay time calculation system including a reproduction device and a propagation delay time calculation device.
The playback device is
Measurement signals are sequentially output from each of the multiple speakers at a timing that does not interfere with time.
The propagation delay time calculation device is
The measurement signal for each speaker is recorded at a predetermined listening position, and the measurement signal is recorded.
Calculate the impulse response characteristics of the measurement signal for each recorded speaker,
The playback device is
The measurement signals are output from all of the plurality of speakers at the same time.
The propagation delay time calculation device is
The measurement signals output from all speakers at the same time are recorded at the listening position.
Calculate the impulse response characteristics of the measurement signals of all recorded speakers,
The cross-correlation of the impulse response characteristics between the calculated measurement signal for each speaker and the measurement signal for all the speakers is calculated.
Based on the calculated cross-correlation result, the propagation delay time of the measurement signal between each of the plurality of speakers and the listening position is calculated.
Propagation delay time calculation system. The first recording step of recording the measurement signal for each speaker, which is output from each of the plurality of speakers and is non-interfering in time, at a predetermined listening position, and
The first impulse response characteristic calculation step for calculating the impulse response characteristics of the measurement signal for each recorded speaker, and
The second recording step of recording the measurement signals output from all the speakers at the same time at the listening position, and
A second impulse response characteristic calculation step for calculating the impulse response characteristics of the recorded measurement signals of all speakers, and
A calculation step for calculating the cross-correlation of the impulse response characteristics between the calculated measurement signal for each speaker and the measurement signal for all the speakers, and
A propagation delay time calculation step for calculating the propagation delay time of the measurement signal between each of the plurality of speakers and the listening position based on the calculated cross-correlation result.
Propagation delay time calculation program to make a computer execute.

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