JP2016063393A - Phase characteristic correction device and phase characteristic correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel phase characteristic correction method capable of obtaining effects even at any position in a listening space and obtaining effects in a mode of a reduced individual difference regarding simultaneous arrival of sound components which are simultaneously generated in an original acoustic signal.SOLUTION: While defining phase characteristics generated by signal processing by a prestage signal processing part 110 as a correction object, a first phase characteristic correction part 121 performs first phase characteristic correction for linearizing the phase characteristics of the correction object in a frequency domain equal to or lower than a predetermined frequency on a signal PAD inputted from the prestage signal processing part 110 and generates a first correction signal FAD. Continuously, a second phase characteristic correction part 122 performs second phase characteristic correction for linearizing the phase characteristics over an entire audio frequency domain on the first correction signal.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a phase characteristic correction apparatus, a phase characteristic correction method, a phase characteristic correction program, and a recording medium on which the phase characteristic correction program is recorded.

  Conventionally, it has been widely performed to perform signal processing on an original sound signal obtained directly from a sound source and output a sound corresponding to the processed sound signal after the signal processing from a sound output device such as a speaker. Yes. As a technique related to such signal processing, based on the average distance between both ears, the time difference between the time when the sound component generated simultaneously in the original sound signal reaches both ears of the listener is minimized within a predetermined frequency range. A correction technique has been proposed (see Patent Document 1: hereinafter referred to as “conventional example”).

  In the conventional technique, when there is one assumed listener position (hereinafter also referred to as “assumed listening position”), that is, when there is one control point, only the assumed listening position is specified. Make the corrections that were made. In addition, when there are a plurality of assumed listening positions, that is, when there are a plurality of control points, an average correction regarding the plurality of control points is performed.

JP 2011-097561 A

  In the technology of the conventional example described above, when there is one assumed listening position, the effect of correction cannot be expected at a position outside the assumed listening position. Further, when there are a plurality of assumed listening positions, the effect of the correction is greatly reduced even if the assumed listening position is compared with a case where there is only one assumed listening position.

  By the way, there are individual differences in the distance between both ears. As a result, in the conventional technique, individual differences occur in the correction effect.

  For this reason, it is possible to obtain a substantial effect at any position in the listening space with respect to the simultaneous arrival of sound components generated simultaneously in the original sound signal, and a new effect that can obtain an effect in a mode with little individual difference. Technology is desired. Meeting this requirement is one of the problems to be solved by the present invention.

  According to the first aspect of the present invention, the first phase characteristic correction for linearizing the phase characteristic, which is the characteristic of the phase change with respect to the frequency change of the correction target, in the first phase characteristic correction target band is applied to the input signal input from the outside. A first phase characteristic correcting unit that generates a first correction signal; and a second phase characteristic correction that linearizes phase characteristics in a second phase characteristic correction target band that includes the first phase characteristic correction target band. And a second phase characteristic correction unit that performs the correction signal and generates a second correction signal.

  The invention according to claim 6 is a phase characteristic correction method used in a phase characteristic correction apparatus for correcting a phase characteristic which is a characteristic of a phase change with respect to a frequency change, wherein the phase characteristic to be corrected is corrected to a first phase characteristic. A first phase characteristic correction step of generating a first correction signal by performing a first phase characteristic correction to be linearized in the target band on an externally input signal; and a second phase including the first phase characteristic correction target band And a second phase characteristic correction step of generating a second correction signal by performing a second phase characteristic correction for linearizing the phase characteristic in the characteristic correction target band on the first correction signal. Is the method.

  A seventh aspect of the invention is a phase characteristic correction program that causes a computer of the phase characteristic correction apparatus to execute the phase characteristic correction method according to the sixth aspect.

  The invention described in claim 8 is a recording medium in which the phase characteristic correction program according to claim 7 is recorded so as to be readable by a computer included in the phase characteristic correction apparatus.

It is a block diagram which shows the structure of an audio equipment provided with the phase characteristic correction apparatus which concerns on one Embodiment of this invention. It is a figure which shows the example of the phase characteristic after the signal processing by the front signal processing part of FIG. It is a block diagram for demonstrating the structure of the phase characteristic correction apparatus of FIG. It is a figure which shows the example of the phase characteristic after the phase characteristic correction | amendment by the 1st phase characteristic correction | amendment part of FIG. It is a figure which shows the example of the phase characteristic after the phase characteristic correction | amendment by the 2nd phase characteristic correction | amendment part of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

[Constitution]
FIG. 1 shows a configuration of an acoustic device 100 including a phase characteristic correction device 120 according to an embodiment. In addition to the phase characteristic correction device 120, the acoustic device 100 includes a pre-stage signal processing unit 110, a sound output unit 130, an input unit 140, and a control unit 150.

  The preceding signal processing unit 110 receives the acoustic signal OAD sent from the sound source device 200. Then, the pre-stage signal processing unit 110 performs pre-stage signal processing such as equalizing on the acoustic signal OAD in a manner in accordance with the pre-stage process designation PPC sent from the control unit 150 to generate the signal PAD. The signal PAD generated in this way is sent to the phase characteristic correction device 120.

  Examples of the sound source device 200 include a CD (Compact Disk) player and a DVD (Digital Versatile Disk) player.

  The sound output unit 130 includes a speaker SP. The sound output unit 130 receives an output sound signal (second correction signal) AOD sent from the phase characteristic correction device 120. Then, the sound output unit 130 outputs a sound corresponding to the output sound signal AOD from the speaker SP.

  The input unit 140 includes a key unit provided in the main body of the acoustic device 100 and / or a remote input device including the key unit. Here, as a key part provided in the main body, a touch panel provided in a display device of a display unit (not shown) can be used. Moreover, it can replace with the structure which has a key part, or can also employ | adopt the structure input with a sound using a voice recognition technique in combination.

  When the user operates the input unit 140, the operation content of the acoustic device 100 is set and an operation command is input. For example, it is possible to specify a mode of pre-stage processing such as equalizing processing in the pre-stage signal processing unit 110. The content input to the input unit 140 is sent to the control unit 150 as input data IPD.

  The control unit 150 performs overall control of the operation of the acoustic device 100 according to the content of the input data IPD sent from the input unit 140. For example, when the content of the input data IPD is the designation of the preceding processing mode in the preceding signal processing unit 110, the preceding processing designation PPC corresponding to the designation of the preceding processing mode is generated. Then, the control unit 150 sends the generated upstream process designation PPC to the upstream signal processing unit 110.

  In addition, the control unit 150 generates a phase characteristic correction designation PCC for linearizing the phase characteristic reflected in the signal PAD generated according to the pre-stage process designation PPC. The phase characteristic correction designation PCC generated in this way is sent to the phase characteristic correction device 120.

  FIG. 2 shows an example of the phase characteristics reflected in the signal PAD. As representatively shown in FIG. 2, generally, the phase characteristic is linear in a high frequency region.

<Configuration of Phase Characteristic Correction Device 120>
Next, the configuration of the phase characteristic correction apparatus 120 will be described.

  As illustrated in FIG. 3, the phase characteristic correction device 120 includes a first phase characteristic correction unit 121 and a second phase characteristic correction unit 122. The second phase characteristic correction unit 122 includes a low-pass filter (LPF) unit 126, a high-pass filter (HPF) unit 127, a delay unit 128, and an addition unit 129.

The first phase characteristic correction unit 121 is a so-called all-pass filter, and in the present embodiment, a plurality of infinite impulse response (IIR) filters are connected in series. The first phase characteristic correction unit 121 receives the signal PAD input from the previous signal processing unit 110. Then, the first phase characteristic correction unit 121 performs phase characteristic correction on the signal PAD so that the phase characteristic in the frequency range equal to or lower than the predetermined frequency f _C is linearized in accordance with the phase characteristic correction designation PCC sent from the control unit 150. The first correction signal FAD is generated. The first correction signal FAD generated in this way is sent to the LPF unit 126 and the HPF unit 127 of the second phase characteristic correction unit 122.

In the phase characteristic corrected by the first phase characteristic correction unit 121, that is, the phase characteristic reflected in the first correction signal FAD, the change in the phase θ with respect to the change in the frequency f in the frequency range below the predetermined frequency f _C. The absolute value of the rate | (dθ / df) _L | is larger than the absolute value | (dθ / df) _H | of the change rate of the phase θ with respect to the change of the frequency f in the frequency range equal to or higher than the predetermined frequency f _C. .

The LPF unit 126 has a function of a Link Witzrei type low-pass filter whose cutoff frequency is a predetermined frequency f _C. The LPF unit 126 receives the first correction signal FAD sent from the first phase characteristic correction unit 121. Then, the LPF unit 126 passes the low frequency component of the first correction signal FAD with a filtering characteristic that uses the predetermined frequency f _C as a cutoff frequency. The signal thus passing through the LPF unit 126 is sent to the adder 129 as a signal LPD.

The HPF unit 127 has a function of a link Witzrei type high-pass filter whose cut-off frequency is a predetermined frequency f _C , and has a filtering characteristic that is symmetric with the LPF unit 126 described above with the predetermined frequency f _C as the center of symmetry. have. For this reason, the HPF unit 127 has the same phase characteristics as the LPF unit 126. The sum of the gain characteristics of the HPF unit 127 and the LPF unit 126 is flat over the entire frequency range.

The HPF unit 127 receives the first correction signal FAD sent from the first phase characteristic correction unit 121. The HPF unit 127 allows the high-frequency component of the first correction signal FAD to pass through with a filtering characteristic that uses the predetermined frequency f _C as a cutoff frequency. The signal thus passing through the HPF unit 127 is sent to the delay unit 128 as a signal HPD.

The delay unit 128 receives the signal HPD sent from the HPF unit 127. Then, the delay unit 128 delays the signal HPD according to the specification of the delay time TD that is the correction mode of the frequency range equal to or higher than the predetermined frequency f _C in the phase characteristic correction specification PCC sent from the control unit 150, and generates the delay signal DAD To do. The delay signal DAD generated in this way is sent to the adder 129.

Note that the control unit 150 determines the absolute value | (dθ / df) _L | of the slope of the phase characteristic below the predetermined frequency f _C reflected in the first correction signal FAD and the phase characteristic above the predetermined frequency f _C. Using the absolute value | (dθ / df) _H | of the slope, a delay time TD expressed by the following equation (1) is designated to the delay unit 128.
TD = | (dθ / df) _L | − | (dθ / df) _H | (1)

  The adder 129 receives the signal LPD sent from the LPF unit 126 and the delayed signal DAD sent from the delay unit 128. Then, the adding unit 129 calculates the sum of the signal LPD and the delay signal DAD, and generates an output sound signal AOD. The output sound signal AOD generated in this way is sent to the sound output unit 130.

FIG. 4 shows the phase characteristics reflected in the first correction signal FAD. As shown in FIG. 4, in the first correction signal FAD, the phase characteristics in the frequency region below the predetermined frequency f _C are linearized. Further, in the example shown in FIG. 4, the phase characteristic of the predetermined frequency f _C or more in the frequency domain, and can approximate a different straight line the slope at the following frequency domain given frequency f _C.

  FIG. 5 also shows the phase characteristics reflected in the output sound signal (second correction signal) AOD. As shown in FIG. 5, the phase characteristic reflected in the output sound signal AOD subjected to the phase characteristic correction by the second phase characteristic correction unit 122 is linearized over the entire range of the audio frequency domain. For this reason, the output sound signal AOD is supplied to the sound output unit 130 in a manner in which the group delay is fixed. That is, sound components that are simultaneously generated in the acoustic signal OAD output from the sound source device 200 are sent to the sound output unit 130 almost simultaneously.

[Operation]
Next, the operation of the acoustic device 100 configured as described above will be described mainly focusing on the phase characteristic correction processing by the phase characteristic correction device 120.

  Note that the sound signal OAD is sequentially transmitted from the sound source device 200. Further, the user designates a pre-processing mode such as equalizing processing in the pre-stage signal processing unit 110, and the pre-processing designation PPC and the phase characteristic correction designation PCC corresponding to the designated pre-processing mode are controlled by the user. Assume that the signal is transmitted from the unit 150 to the upstream signal processing unit 110 and the phase characteristic correction device 120 (see FIG. 1).

  In this state, when receiving the acoustic signal OAD, the upstream signal processing unit 110 performs upstream signal processing such as equalizing on the acoustic signal OAD in accordance with the upstream processing designation PPC sent from the control unit 150, and the signal Generate a PAD. Then, the upstream signal processing unit 110 sends the generated signal PAD to the phase characteristic correction device 120 (see FIG. 1).

In the phase characteristic correction apparatus 120, the first phase characteristic correction unit 121 receives the signal PAD sent from the previous stage signal processing unit 110. Upon receiving the signal PAD, the first phase characteristic correction unit 121 performs phase correction in which the phase characteristic in the frequency range below the predetermined frequency f _C is linearized according to the phase characteristic correction designation PCC sent from the control unit 150. (See FIG. 4) to generate the first correction signal FAD. Then, the first phase characteristic correction unit 121 sends the generated first correction signal FAD to the second phase characteristic correction unit 122 (see FIG. 3).

In the second phase characteristic correction unit 122, the LPF unit 126 and the HPF unit 127 receive the first correction signal FAD sent from the first phase characteristic correction unit 121. Upon receiving the first correction signal FAD, the LPF unit 126 passes the low-frequency component of the first correction signal FAD with a filtering characteristic having the predetermined frequency f _C as a cutoff frequency. The signal thus passing through the LPF unit 126 is sent to the adder 129 as a signal LPD (see FIG. 3).

On the other hand, when receiving the first correction signal FAD, the HPF unit 127 passes the high-frequency component of the first correction signal FAD with a filtering characteristic having the predetermined frequency f _C as a cutoff frequency. The signal thus passing through the HPF unit 127 is sent to the delay unit 128 as a signal HPD (see FIG. 3).

  When receiving the signal HPD, the delay unit 128 delays the signal HPD in accordance with the designation of the delay time TD in the phase characteristic correction designation PCC sent from the control unit 150, and generates the delay signal DAD. Then, the delay unit 128 sends the generated delay signal DAD to the addition unit 129 (see FIG. 3).

  Upon receiving the signal LPD and the delay signal DAD, the adder 129 calculates the sum of the signal LPD and the delay signal DAD, and generates an output sound signal AOD. Then, the adding unit 129 sends the generated output sound signal AOD to the sound output unit 130 (see FIG. 3).

  The phase characteristic reflected in the output sound signal AOD is linearized over the entire range of the sound frequency region. For this reason, the output sound signal AOD is supplied to the sound output unit 130 in a manner in which the group delay is fixed.

  When the output sound signal AOD is received, a sound corresponding to the output sound signal AOD is output from the speaker SP. For this reason, a sound in which sound components simultaneously generated in the acoustic signal OAD output from the sound source device 200 reach almost simultaneously at any position in the listening space is output from the speaker SP.

As described above, in the present embodiment, the first phase characteristic correction unit 121 sets the phase characteristic generated by the signal processing by the previous stage signal processing unit 110 as a correction target, and sets the phase characteristic of the correction target to a predetermined frequency f _C or less. The first phase characteristic correction to be linearized in the frequency region (first phase characteristic correction target region) is performed on the signal PAD input from the previous signal processing unit 110 to generate the first correction signal FAD. Subsequently, the second phase characteristic correction unit 122 performs second phase characteristic correction on the first correction signal FAD to linearize the entire range (second phase characteristic correction target region) of the audio frequency region.

  Therefore, according to the present embodiment, the sound component generated at the same time in the acoustic signal OAD output from the sound source device 200 is made to reach the sound output unit 130 almost simultaneously. Can do. As a result, regarding the simultaneous arrival of the sound components generated simultaneously in the acoustic signal OAD, a substantial effect can be obtained at any position in the listening space, and an effect can be obtained in a mode with little individual difference. Phase characteristic correction can be performed. For this reason, the sound corresponding to the sound source can be provided to the listener in a manner that accurately reflects the intention of the sound source producer.

Further, in the present embodiment, the second phase characteristic correcting unit 122, a predetermined frequency f _C and LPF 126 to the cut-off frequency; the predetermined frequency f _C and HPF 127 to cut-off frequency; the HPF 127 A delay unit 128 that adds a delay to the passed signal; and an adder 129 that adds the signal LPD that has passed through the LPF unit 126 and the delayed signal DAD output from the delay unit 128. For this reason, the 2nd phase characteristic correction | amendment part 122 is easily realizable.

Further, in the present embodiment, the LPF unit 126 has a function of a Linkwitz Reilly type low-pass filter, and the HPF unit 127 has a function of a Linkwitz Reiri type high-pass filter, and has a predetermined frequency f _C as a symmetry center. , A configuration having a filtering characteristic symmetrical to that of the LPF unit 126. For this reason, the HPF unit 127 has the same phase characteristic as the LPF unit 126, and the sum of the gain characteristic of the HPF unit 127 and the gain characteristic of the LPF unit 126 can be made flat over the entire frequency range. As a result, the second phase characteristic correction unit 122 according to the present invention can be realized with a very simple configuration.

[Modification of Embodiment]
The present invention is not limited to the above-described embodiment, and various modifications are possible.

  For example, in the above embodiment, the phase characteristic correction is performed assuming an acoustic signal having a one-channel configuration. On the other hand, in the case of an acoustic signal having a plurality of channels, the same phase characteristic correction as in the above-described embodiment may be performed so that the group delay is the same for each channel.

  Further, in the above-described embodiment, the first frequency region below the predetermined frequency and the second frequency region above the predetermined frequency are divided into two frequency regions. After performing the one phase characteristic correction, the second phase characteristic correction unit performs the second phase characteristic correction for the entire range of the audio frequency region. On the other hand, after dividing into three or more frequency regions, phase characteristic correction corresponding to each divided frequency region may be performed to linearize the phase characteristics in the entire range of the desired frequency region.

  In the above embodiment, the first correction signal whose phase characteristic is corrected by the first phase characteristic correction unit is only passed through the LPF unit in the second phase characteristic correction unit. On the other hand, after further correcting the inclination of the phase characteristic in the signal via the LPF unit, the signal may be supplied to the addition unit of the second phase characteristic correction unit.

  Further, in the above embodiment, the phase characteristic to be corrected is the phase characteristic in the previous stage processing signal output from the previous stage signal processing unit. On the other hand, the phase characteristic to be corrected can be a phase characteristic obtained by synthesizing the phase characteristic in the pre-processed signal output from the pre-stage signal processing unit and the phase characteristic of the sound output unit. In this case, the group delay in the sound output from the sound output unit can be made constant.

  Note that the phase characteristic correction of the above embodiment is configured as a computer as a calculation unit including a DSP (Digital Signal Processor) and the like, and a program prepared in advance is executed by the computer, so that in the above embodiment Some or all of the processing may be executed. This program may be acquired in a form recorded on a portable recording medium such as a CD-ROM or DVD, or may be acquired in a form of delivery via a network such as the Internet. .

DESCRIPTION OF SYMBOLS 120 ... Phase characteristic correction apparatus 121 ... 1st phase characteristic correction part 122 ... 2nd phase characteristic correction part 126 ... LPF part (low-pass filter)
127 ... HPF section (high pass filter)
128 ... delay unit 129 ... addition unit

Claims (8)

A first phase characteristic correction for linearizing a phase characteristic that is a characteristic of a phase change with respect to a frequency change to be corrected in a first phase characteristic correction target band is performed on an input signal input from the outside, and a first correction signal is generated. One phase characteristic correction unit;
Second phase characteristic correction for generating a second correction signal by performing a second phase characteristic correction for linearizing the phase characteristic in the second phase characteristic correction target band including the first phase characteristic correction target band for the first correction signal. Part;
A phase characteristic correction apparatus comprising: The second phase characteristic correction unit corrects a phase characteristic in at least one frequency band among a plurality of frequency bands when the second phase characteristic correction target region is divided;
The phase characteristic correcting apparatus according to claim 1. The plurality of frequency bands are two frequency bands;
The first phase characteristic correction target band is a frequency band equal to or lower than a predetermined frequency in the second phase characteristic correction target band,
The second phase characteristic correction unit corrects a phase characteristic in a frequency band equal to or higher than the predetermined frequency in the second phase characteristic correction target band;
The phase characteristic correcting apparatus according to claim 2. The second phase characteristic correction unit includes:
A Link Witzrei type low-pass filter having the predetermined frequency as a cutoff frequency;
A Link Witzrei type high-pass filter having the predetermined frequency as a cutoff frequency;
A delay unit that adds a delay to the signal that has passed through the high-pass filter;
An adder that adds the signal that has passed through the low-pass filter and the signal output from the delay unit;
The phase characteristic correction apparatus according to claim 3, comprising: The second correction signal is supplied to a sound output unit,
The phase characteristic to be corrected is a phase characteristic obtained by combining the phase characteristic reflected in the input signal and the phase characteristic of the sound output unit.
The phase characteristic correction apparatus according to claim 1, wherein A phase characteristic correction method used in a phase characteristic correction device that corrects a phase characteristic that is a characteristic of a phase change with respect to a frequency change,
A first phase characteristic correction step of generating a first correction signal by performing a first phase characteristic correction for linearizing the phase characteristic to be corrected in the first phase characteristic correction target band on an input signal input from the outside;
Second phase characteristic correction for generating a second correction signal by performing a second phase characteristic correction for linearizing the phase characteristic in the second phase characteristic correction target band including the first phase characteristic correction target band for the first correction signal. Process and;
A phase characteristic correction method comprising:   A phase characteristic correction program causing a computer included in the phase characteristic correction apparatus to execute the phase characteristic correction method according to claim 6.   A recording medium on which the phase characteristic correction program according to claim 7 is recorded so as to be readable by a computer included in the phase characteristic correction apparatus.

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