JP2011035584A - Acoustic device, phase correction method, phase correction program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and accurately perform phase correction of output sound. <P>SOLUTION: On the basis of a test sound signal of a single frequency, levels of a first test sound outputted from a first loudspeaker, a second test sound outputted from a second loudspeaker, and a composite sound of the first and second test sounds simultaneously outputted from the first and second loudspeakers are detected (step S22). An absolute value of a phase difference between the first test sound and the second test sound in an assumed listening position is calculated (step S23). Subsequently, a level of a composite sound resulting from delaying a phase of the first sound by an amount corresponding to the absolute value and a level of a composite sound resulting from delaying a phase of the second sound by the amount corresponding to the absolute value are detected, and both of the levels are compared to specify a direction of the phase difference (step S24). On the basis of the phase difference obtained in this manner, phase correction of sounds outputted from the first loudspeaker and sounds outputted from the second loudspeaker is performed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  Conventionally, acoustic devices that employ a two-channel stereo system or a multi-channel surround system have been widely used. By using such an acoustic device, it is possible to enjoy audio content full of a sense of reality in a home space or a vehicle space.

  By the way, the installation environment of the acoustic device is various. For this reason, there are often cases where a plurality of speakers that output audio cannot be arranged symmetrically as assumed by the creator of the audio content (hereinafter referred to as “content creator”). In particular, when a 2-channel stereo system or multi-channel surround system audio device is mounted on a vehicle, there are restrictions on the seating position as a listening position, and a plurality of speakers are arranged symmetrically as assumed by the content creator. In most cases, this cannot be done. For this reason, there often occurred a situation where the sound image localization intended by the content creator could not be realized.

  In order to prevent the occurrence of such a situation and realize the sound image localization intended by the content creator, it is necessary to synchronize the output sound from a plurality of speakers as intended by the content creator. In order to achieve such synchronization, a test sound is output from each speaker and picked up at an assumed listening position, and a technique (so-called time alignment) that measures a propagation delay time until the output sound from each speaker reaches the assumed listening position. (Refer to Patent Document 1: hereinafter referred to as “conventional example”).

JP 2008-209490 A

  In the conventional technique described above, since the propagation delay time of the sound from each speaker to the assumed listening position is measured, it is essential to accurately synchronize between the test sound generating means and the sound collecting means. For this reason, it was difficult to easily measure the propagation delay time.

  By the way, for sound image localization intended for content creation, it is important to maintain the phase relationship in the low sound range between sounds output from each speaker even at the assumed listening position. However, since the wavelength becomes longer as the sound frequency is lower, in the conventional technique, the measurement accuracy of the propagation delay time for the sound in the low sound range is lowered.

  Further, in the conventional technique, if the sound transfer characteristic of the space in which the sound propagates is complicated, the waveform of the collected sound may be greatly different from the original waveform of the test sound. For example, the level of the second wave (first reflected wave) may be larger than the first wave (direct wave) of the test sound output from the speaker. If the waveform of the collected sound is greatly different from the original waveform of the test sound, the measurement error of the propagation delay time becomes large.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an acoustic device and a phase correction method capable of performing phase correction easily and accurately.

  The invention according to claim 1 is an acoustic device for outputting reproduced sound from a plurality of speakers including a first speaker and a second speaker, and generating means for generating at least one single frequency test sound signal And a sound collecting means for picking up reproduced sound that is arranged at an assumed listening position and reproduced and output from the plurality of speakers based on the test sound signal; and a detection for detecting a signal level of a sound collection result by the sound collecting means. And a detection result by the detection means for the first sound from the first speaker, a detection result by the detection means for the second sound from the second speaker, for each type of the test sound signal, and Based on the detection result of the detection means for the synthesized sound of the first sound and the second sound, the first sound and the second sound at the assumed listening position Calculating means for calculating an absolute value of the phase difference; control means for controlling phase adjustment of the first sound and the second sound based on a calculation result by the calculating means; and according to adjustment control by the control means And an adjusting device for adjusting the phase.

  The invention according to claim 10 includes a plurality of speakers including a first speaker and a second speaker, and outputs reproduced sound; generating means for generating at least one type of single-frequency test sound signal; Sound collecting means disposed at a position and collecting reproduced sound reproduced and output from the plurality of speakers based on the test sound signal; and detecting means for detecting a signal level of a sound collection result by the sound collecting means; A phase correction method used in an acoustic device comprising: a first acquisition step of acquiring a first detection result by the detection means for the first sound from the first speaker for each type of the test sound signal; A second acquisition step of acquiring a detection result by the detection unit for the second sound from the second speaker; and a previous about the synthesized sound of the first sound and the second sound A third acquisition step of acquiring a detection result by the detection means; and an absolute value of a phase difference between the first sound and the second sound at the assumed listening position based on the acquisition result in the first to third acquisition steps. A phase correction method comprising: a calculation step of calculating; and a control step of controlling phase adjustment of the first voice and the second voice based on a calculation result in the calculation step.

  According to an eleventh aspect of the present invention, there is provided a phase correction program that causes a calculation means to execute the phase correction method according to the tenth aspect.

  According to a twelfth aspect of the present invention, there is provided a recording medium in which the phase correction program according to the eleventh aspect is recorded so as to be readable by the calculation means.

1 is a block diagram schematically showing a configuration of an audio device according to an embodiment of the present invention. It is a figure for demonstrating the example of the arrangement position of the speaker of FIG. 1, and a microphone. It is a block diagram for demonstrating the structure of the level detection part of FIG. It is a block diagram for demonstrating the structure of the digital processing part of FIG. It is a block diagram for demonstrating the structure of the analog process part of FIG. 3 is a flowchart for explaining phase correction processing by the apparatus of FIG. 1. It is a flowchart for demonstrating the specific process of correction | amendment object phase difference regarding the measurement frequency in FIG. It is a flowchart for demonstrating the level detection process of the sound collection result of the test sound in FIG. It is a figure for demonstrating the principle of calculation of the absolute value of the phase difference in FIG. It is a flowchart for demonstrating the identification process of the direction of the phase difference in FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a two-channel stereo system will be adopted and described as an example of an acoustic device mounted on a vehicle CR (see FIG. 2 described later). In the following description and drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

[Constitution]
FIG. 1 is a block diagram illustrating a schematic configuration of an acoustic device 100 according to the present embodiment.

As shown in FIG. 1, the acoustic apparatus 100 includes a signal processing unit 110, and a tone generator unit 120, a speaker 130 _L as the first speaker, a speaker 130 _R as the second speaker. The acoustic device 100 includes a sound collection unit 140 as a sound collection unit, a display unit 150, and an operation input unit 160. Here, the speaker 130 _L is a left speaker, and the speaker 130 _R is a right speaker.

The elements 120, 130 _L , 130 _R , 140, 150, 160 other than the signal processing unit 110 are connected to the signal processing unit 110.

The signal processing unit 110 processes the content data CTD from the sound source unit 120, supplies the audio output signals AOS _L and AOS _R as the processing results to the speakers 130 _L and 130 _R, and performs phase adjustment processing and the like. Perform the process. Details of the signal processing unit 110 will be described later.

  The sound source unit 120 outputs content data CTD under the control of the read command CSL from the signal processing unit 110. In the present embodiment, the content data CTD carries signals of both the left channel (hereinafter referred to as “L channel”) and the right channel (hereinafter referred to as “R channel”) in the 2-channel stereo system. It has become.

That is, the content data CTD carries an L channel signal and an R channel signal. The L channel signal and the R channel signal in the content data CTD are signals intended to be reproduced and output by the speaker 130 _L and the speaker 130 _R by the producer of the audio content. The content data CTD output from the sound source unit 120 is supplied to the signal processing unit 110.

  For example, when the audio device 100 is a device that reproduces audio content recorded on a recording medium RM such as a DVD (Digital Versatile Disk), the sound source unit 120 reads the audio content from the recording medium. Means. When the acoustic device 100 is a device that reproduces audio content acquired by receiving broadcast waves, the sound source unit 120 includes content extraction means for extracting audio content data from the broadcast wave reception results. become.

Each of the speakers 130 _L and 130 _R reproduces and outputs music in accordance with the audio output signals AOS _L and AOS _R sent from the signal processing unit 110. In the present embodiment, as shown in FIG. 2, the speaker 130 _L is arranged in front door housing the passenger side. The speaker 130 _L is arranged so as to face the front passenger seat side. The speaker 130 _R is disposed in the front door casing on the driver's seat side. The speaker 130 _R is arranged to face the driver's seat side.

  Returning to FIG. 1, the sound collection unit 140 includes (i) a microphone 141 that collects ambient sound and converts it into an electrical analog audio signal, and (ii) an amplifier that amplifies the analog audio signal output from the microphone 141, (Iii) An AD converter (Analog to Digital Converter) that converts an amplified analog audio signal into a digital audio signal is provided. Here, the microphone 141 is disposed at an assumed listening position in the passenger compartment space ASP shown in FIG. FIG. 2 shows an example in which the position of the head of the listener seated in the driver's seat is the assumed listening position, and the microphone 141 is disposed at the assumed listening position. The sound collection result by the sound collection unit 140 is reported to the signal processing unit 110 as sound collection result data AAD.

  Returning to FIG. 1, the display unit 150 is sent from, for example, (i) a display device such as a liquid crystal panel, an organic EL (Electro Luminescence) panel, or a PDP (Plasma Display Panel), and (ii) a signal processing unit 110. Based on the display control data that has been received, a display controller such as a graphic renderer that controls the entire display unit 150, and (iii) a display image memory that stores display image data are provided. The display unit 150 displays operation guidance information and the like according to the display data IMD sent from the signal processing unit 110.

  The operation input unit 160 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 part, a touch panel provided in a display device of the display unit 150 can be used. In addition, 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 operation input unit 160, the operation content of the acoustic device 100 is set. For example, an input by a user such as an audio content reproduction command and a phase adjustment command for each channel is performed using the operation input unit 160. Such input contents are sent from the operation input unit 160 to the signal processing unit 110 as operation input data IPD.

Next, the signal processing unit 110 will be described. As described above, the signal processing unit 110 processes the content data CTD from the sound source unit 120 and supplies the audio output signals AOS _L and AOS _R as the processing results to the speakers 130 _L and 130 _R. Various processing such as phase adjustment processing is performed. The signal processing unit 110 having such a function includes a level detection unit 111, a digital processing unit 112, and an analog processing unit 113. Further, the signal processing unit 110 includes a control processing unit 119 as a calculation unit and a control unit.

The level detection unit 111 detects the level of the test sound output from the speaker 130 _L and / or the speaker 130 _R and reaching the microphone 141 based on the sound collection result data AAD sent from the sound collection unit 140. To do. As shown in FIG. 3, the level detection unit 111 having such a function includes a variable bandpass filter (BPF) unit 251 as a bandpass filter unit and a signal level detection unit 252 as a detection unit.

  The variable BPF unit 251 receives the sound collection result data AAD sent from the sound collection unit 140. Then, the variable BPF unit 251 selectively allows a signal component having a frequency near the frequency of the test voice designated by the frequency designation FRC sent from the control processing unit 119 to pass therethrough. The signal FLD that has passed through the variable BPF unit 251 is sent to the signal level detection unit 252.

  The signal level detection unit 252 receives the signal FLD sent from the variable BPF unit 251. The signal level detection unit 252 performs synchronous addition in which waveforms for each cycle length of the frequency of the test voice designated by the frequency designation FRC sent from the control processing unit 119 are added for a first predetermined number of times. Then, the signal level detection unit 252 calculates the effective value of the one-cycle waveform obtained as a result of the synchronous addition, and detects the level of the test signal that has reached the microphone 141. The detection result by the signal level detection unit 252 is sent to the control processing unit 119 as the level detection result DLD.

  The “first predetermined number of times” is determined in advance based on experiments, simulations, experience, and the like from the viewpoint of reducing noise contribution in the level detection result DLD and speeding up the level detection.

Returning to FIG. 1, the digital processing unit 112 performs digital processing of the audio signal under the control of the control processing unit 119 to generate the phase adjustment signals AOD _L and AOD _R. As shown in FIG. 4, the digital processing unit 112 having such a function includes a channel separation unit 211, signal selection units 212 _L and 212 _R , a part of the adjustment unit, and a phase adjustment unit 213 _L as an all-pass filter unit. , 213 _R and a test signal generation unit 215 as generation means.

The channel separation unit 211 receives the content data CTD from the sound source unit 120. The channel separating unit 211, the content data CTD, L in two-channel stereo system, corresponding to the R channel two separate channel signals SCD _L, separating the SCD _R. Such separation channel signal SCD _L generated in the are sent to the signal selector 212 _L. Further, the generated separated channel signal SCD _R is transmitted to the signal selecting unit 212 _R.

The signal selection unit 212 _L includes a switch element. The signal selection section 212 _L receives a separated channel signal SCD _L sent from the channel separation section 211, a test sound signal TSD sent from the test signal generator 215. Then, the signal selection unit 212 _L selects and outputs one of the separation channel signal SCD _L , the test audio signal TSD, and the “0” level signal according to the selection designation SLC _L sent from the control processing unit 119. The signal selected by the signal selection unit 212 _L is sent to the phase adjustment unit 213 _L as a signal SLD _L.

Similar to the signal selection unit 212 _L , the signal selection unit 212 _R includes a switch element. The signal selection section 212 _R receives a separated channel signal SCD _R sent from the channel separation section 211, a test sound signal TSD sent from the test signal generator 215. Then, the signal selection unit 212 _R in accordance with the selected and designated SLC _R sent from the control unit 119 selects and outputs one of the separated channel signals SCD _R, test sound signal TSD and "0" level signal. Signal selected by the signal selecting unit 212 _R as a signal SLD _R, is sent to the phase adjustment unit 213 _R.

The phase adjusting unit 213 _L has a variable all-pass filter function. The phase adjustment unit 213 _L receives the signal SLD _L sent from the signal selection unit 212 _L. Then, the phase adjustment unit 213 _L has a phase frequency characteristic according to the phase adjustment parameter value designated by the phase adjustment designation PHC _L sent from the control processing unit 119 while keeping the amplitude frequency characteristic of the signal SLD _L constant. The phase of the signal SLD _L is adjusted to generate a phase adjustment signal AOD _L. The phase adjustment signal AOD _L generated in this way is sent to the analog processing unit 113.

The phase adjustment unit 213 _R has a variable all-pass filter function, like the phase adjustment unit 213 _L. The phase adjustment unit 213 _R receives the signal SLD _R sent from the signal selection unit 212 _R. Then, the phase adjustment unit 213 _R, while the constant amplitude frequency characteristic of the signal SLD _R, the phase frequency characteristics in accordance with the phase adjustment parameter values specified in sent from the control processor unit 119 phase adjustment specified PHC _R, It adjusts the phase of the signal SLD _R, generates a phase adjustment signal AOD _R. The phase adjustment signal AOD _R generated in this way is sent to the analog processing unit 113.

  The test signal generation unit 215 generates the test audio signal TSD according to the test audio signal designation TSC sent from the control processing unit 119. When the test audio signal designation TSC designates a frequency, the test signal generation unit 215 generates a sine wave signal having the designated frequency as the test audio signal TSD. Further, the test signal generation unit 215 does not generate the test audio signal TSD when it is specified that the test audio signal TSD is not generated by the test audio signal specification TSC.

The control processing unit 119 selects one of a plurality of test audio frequencies F ₁ , F ₂ ,..., F _N (F ₁ <F ₂ <... <F _N ) belonging to the low frequency range according to the test audio signal designation TSC. This is specified for the test signal generation unit 215. Here, the minimum value F ₁ and the maximum value F _N of the test sound frequency are determined in advance based on experiments, simulations, experiences, and the like from the viewpoint of the effectiveness of sound image localization control by phase correction.

In the present embodiment, all of the ratio values (F _k / F _{k + 1} (k = 1 to N−1)) are the same. The value of the ratio is determined in advance based on experiments, simulations, experiences, and the like from the viewpoint of increasing the accuracy of phase correction and speeding up the phase correction process, as well as the number N of test audio frequencies.

Returning to FIG. 1, the analog processing unit 113 receives the phase adjustment signals AOD _L and AOD _R sent from the digital processing unit 112. Then, the analog processing unit 113 generates the audio output signals AOS _L and AOS _R under the control of the control processing unit 119 and sends them to the speakers 130 _L and 130 _R. As illustrated in FIG. 5, the analog processing unit 113 having such a function includes a DA (Digital to Analogue) conversion unit 241, a volume adjustment unit 242, and a power amplification unit 243.

The DA converter 241 receives the phase adjustment signals AOD _L and AOD _R from the digital processor 112. Then, the DA converter 241 converts the phase adjustment signals AOD _L and AOD _R into analog signals. The DA converter 241 includes two DA converters configured similarly to each other in correspondence with two types of digital signals. The conversion result by the DA conversion unit 241 is sent to the volume adjustment unit 242.

  The volume control unit 242 receives an analog signal that is a conversion result of the DA conversion unit 241. Then, the volume adjustment unit 242 performs volume adjustment processing on the received analog signal in accordance with the volume adjustment command VLC from the control processing unit 119. The volume adjusting unit 242 is configured to include two electronic volume elements and the like configured in the same manner, corresponding to two types of analog signals. A volume adjustment signal that is an adjustment result by the volume adjustment unit 242 is sent to the power amplification unit 243.

The power amplification unit 243 receives the volume adjustment signal from the volume adjustment unit 242. The power amplifier 243 power-amplifies the volume adjustment signal. The power amplifying unit 243 includes two power amplifiers configured similarly to each other corresponding to the two kinds of volume adjustment signals. Audio output signals AOS _L and AOS _R that are amplification results by the power amplifier 243 are sent to the speakers 130 _L and 130 _R.

  Returning to FIG. 1, the control processing unit 119 exerts the function of the acoustic device 100 while controlling the other components described above. The control processing unit 119 outputs the display data IMD and causes the display unit 150 to display a guidance screen for assisting the user in specifying audio content to be reproduced. When the reproduction command specifying the audio content input to the operation input unit 160 is notified as the operation input data IPD, the control unit 119 issues a read command CSL to the sound source unit 120, and the content data CTD Control reading.

When the phase adjustment command input to the operation input unit 160 is notified as the operation input data IPD, at least the frequency range from the frequency F ₁ to the frequency F _{N is set} between the sounds output from the speakers 130 _L and 130 _R. The phase correction is performed so that the phase relationship is maintained even at the assumed listening position. The phase correction process will be described later.

In addition, the control processing unit 119 controls the volume adjustment unit 242 to adjust the output volume from the speakers 130 _L and 130 _R. During the control of the volume adjusting unit 242, the control processing unit 119 generates a volume adjustment command VLC according to the volume designation input to the operation input unit 160 during the playback operation of the content audio, and proceeds to the volume adjusting unit 242. Issue.

[Operation]
Next, the operation of the acoustic device 100 configured as described above will be described mainly focusing on the phase correction processing relating to the sound output from the speakers 130 _L and 130 _R.

  Such a phase correction process starts when the user operates the operation input unit 160 and inputs a phase correction command. When the operation input data IPD is notified that the phase correction command has been input to the operation input unit 160, the control processing unit 119 performs initial setting in step S11 of FIG.

In this initial setting, the control processing unit 119 issues a volume adjustment command VLC designating an appropriate output volume to the volume adjustment unit 242 when detecting the phase difference, regardless of the output volume designation state so far. In addition, the control processing unit 119 sends phase adjustment designations PHC _L and PHC _R that designate phase adjustment parameter values when phase adjustment is not performed to the phase adjustment units 213 _L and 213 _R.

Next, in step S12, the control processing unit 119 sets the first test audio frequency as the measurement frequency. In the present embodiment, the frequency F ₁ is set to the measurement frequency as the first test audio frequency.

Next, in step S13, the phase difference between the test sounds output from the speakers 130 _L and 130 _{R is} specified for the set measurement frequency. In this phase difference specifying process, as shown in FIG. 7, first, in step S <b> 21, the control processing unit 119 performs settings for test sound generation and sound collection. At the time of such setting, the control processing unit 119 sends a test audio signal designation TSC designating the measurement frequency (test audio frequency) F _j to the test signal generation unit 215. Upon receiving the test audio signal designation TSC, the test signal generation unit 215 generates a sine wave signal having the measurement frequency F _j as the test audio signal TSD.

In addition, the control processing unit 119 sends a frequency designation FRC designating the measurement frequency F _j to the level detection unit 111. In the level detection unit 111, the variable BPF unit 251 and the signal level detection unit 252 receive the frequency designation FRC.

The variable BPF unit 251 that has received the frequency designation FRC selectively allows a signal component having a frequency near the measurement frequency F _j in the sound collection result data AAD sent from the sound collection unit 140 to pass therethrough. In addition, the signal level detection unit 252 that has received the frequency designation FRC performs synchronous addition for adding the waveform for each cycle length of the measurement frequency F _j over the first predetermined number of times for the signal FLD sent from the variable BPF unit 251. After that, the effective value of the waveform having one cycle length obtained as a result of the synchronous addition is calculated, and the calculation result is sent to the control processing unit 119 as the level detection result DLD.

Next, in step S22, a level detection process of the sound collection result of the test sound is performed.
In step S22, as shown in FIG. 8, first, in step S31, the acquisition of the speaker 130 _L sound pickup level only in a state where the test sound is output A _L (F _j) is performed. Upon detection of the sound collecting level A _L (F _j), the control processing unit 119, and sends the selection specifying SLC _L indicating to select a test sound signal TSD to the signal selection section 212 _L, select "0" level signal Send select from SLC _R in should do effect to the signal selecting unit 212 _R. As a result, a sine wave test sound having the measurement frequency F _j is output from the speaker 130 _L, and no sound is output from the speaker 130 _R.

After entering the sound output state, the control processing unit 119 collects the level detection result DLD sent from the level detection unit 111 for the second predetermined number of times. Then, the control processing unit 119 obtains the sound collection level A _L (F _j ) by calculating the average value of the collected level detection results DLD.

  Note that the “second predetermined number of times” is determined in advance based on experiments, simulations, experiences, and the like from the viewpoint of improving the accuracy of the sound collection level and speeding up the acquisition of the sound collection level.

Then, in step S32, the acquisition of sound pickup level only from the speaker 130 _R in a state in which the test sound is output A _R (F _j) is performed. Upon detection of the sound collecting level A _R (F _j), the control processing unit 119, and sends the selection specifying SLC _L indicating to select the "0" level signal signal selector to 212 _L, select the test audio signal TSD Send select from SLC _R in should do effect to the signal selecting unit 212 _R. As a result, no sound is output from the speaker 130 _L, and a sine wave test sound of the measurement frequency F _j is output from the speaker 130 _R.

After entering the sound output state, the control processing unit 119 collects the level detection result DLD sent from the level detection unit 111 for the second predetermined number of times. Then, the control processing unit 119 obtains the sound collection level A _R (F _j ) by calculating the average value of the collected level detection results DLD.

In step S33, the sound pickup level A _LR (F _j ) is acquired in a state where the test sound is output from both the speaker 130 _L and the speaker 130 _R. Upon detection of the sound collecting level A _LR (F _j), the control processing unit 119, and sends the selection specifying SLC _L indicating to select a test sound signal TSD to the signal selection section 212 _L, to select the test sound signal TSD Send select from SLC _R to the effect that the signal selector 212 _R. As a result, a sine wave test sound having the measurement frequency F _j is output from both the speaker 130 _L and the speaker 130 _R.

After entering the sound output state, the control processing unit 119 collects the level detection result DLD sent from the level detection unit 111 for the second predetermined number of times. Then, the control processing unit 119 obtains the sound collection level A _LR (F _j ) by calculating the average value of the collected level detection results DLD.

In addition, the relationship between the sound collection levels A _L (F _j ), A _R (F _j ), and A _LR (F _j ) acquired in the above steps S31 to S33 is as shown in FIG. The angle in FIG. 9 (in this embodiment, the angle in which the counterclockwise direction in FIG. 9 is defined as the positive direction) φ _j is the test sound output from the speaker 130 _L and the test sound output from the speaker 130 _R. And the phase difference at the assumed listening position. Hereinafter, it is referred to as “phase difference φ _j ”.

Then, the absolute value of the phase difference φ _j uses sound collection levels A _L (F _j ), A _R (F _j ), A _LR (F _j ) according to the following equation (1) according to the second cosine theorem. (The angle unit is “degrees”).
| Φ _j | = 180−cos ⁻¹ [{(A _L (F _j )) ² + (A _L (F _j )) ² − (A _LR (F _j )) ² }
_{/(2.A L} (F _j ) · A _R (F _j ))] (1)

Note that the value | φ _j | calculated by the expression (1) is determined within a range of “0 degrees to 180 degrees”.

  When the process of step S33 ends, the process of step S22 ends. Then, the process proceeds to step S23 in FIG.

In step S23, the control unit 119 calculates the test sound output from the speaker 130 _L, the absolute value of the phase difference phi _j of supposition listening position the test sound output from the speaker 130 _R. Such calculation is performed using the above-described equation (1) using the acquired sound collection levels A _L (F _j ), A _R (F _j ), and A _LR (F _j ).

Next, in step S24, the control processing unit 119 specifies the direction of the phase difference. In a specific direction such phase difference, as shown in FIG. 10, first, in step S41, the control unit 119, the phase of the test sound output from the speaker 130 _L, the phase adjustment at the beginning of step S24 A phase adjustment parameter value delayed by a value | φ _j | from the state is calculated. Then, the control processing unit 119 sends the phase adjustment designation PHC _L designating the phase adjustment parameter value calculated this time to the phase adjustment unit 213 _L. As a result, the test sound to which the phase delay of the value | φ _j | is newly added is output from the speaker 130 _L, and the test sound of the measurement frequency F _j in the phase adjustment state at the start of step S 24 is output from the speaker 130. _The status is output from _R.

After entering the sound output state, in step S42, the control processing unit 119 collects the level detection result DLD sent from the level detection unit 111 for the second predetermined number of times. Then, the control processing unit 119 _obtains the sound collection level A _{LR_dL} (F _j ) by calculating the average value of the collected level detection results DLD.

Then, in step S43, the control unit 119, the phase of the test sound outputted from the speaker 130 _R, the phase adjustment state value at the start of step S24 | calculating a phase adjustment parameter values delaying | phi _j. Then, the control processing unit 119 sets the phase adjustment designation PHC _L that designates the phase adjustment parameter value that sets the phase of the test sound output from the speaker 130 _L as the phase adjustment state at the start of step S24 to the phase adjustment unit 213 _L. And the phase adjustment designation PHC _R designating the phase adjustment parameter value calculated this time is sent to the phase adjustment unit 213 _R. As a result, the test sound in the phase adjustment state at the start of step S24 is output from the speaker 130 _L , and the test sound to which the phase delay of the value | φ _j | is newly added is output from the speaker 130 _R. It becomes a state.

After entering the sound output state, in step S44, the control processing unit 119 collects the level detection result DLD sent from the level detection unit 111 for the second predetermined number of times. Then, the control processing unit 119 _obtains the sound collection level A _{LR_dR} (F _j ) by calculating the average value of the collected level detection results DLD.

Thus sound pickup level A _{LR_dL} (F _j), the A _{LR_dR} (F _j) is acquired, at step S45, the control processing section 119, sound pickup level A _{LR_dL} (F _j) and sound pickup level A _{LR_dR} (F Compare size with _j ). Based on the result of the size comparison, in step S46, the control processing unit 119 specifies the direction of the phase difference φ _j .

That is, in step S46, if the sound collection level A _{LR_dL} (F _j ) is greater than the sound collection level A _{LR_dR} (F _j ), the control processing unit 119 _causes the speaker 130 _{L to} start at step S24. who test sound output from the, than the test sound output from the speaker 130 _R, specifies that advances the phase in supposition listening position. On the other hand, when the sound collection level A _{LR — dL} (F _j ) is smaller than the sound collection level A _{LR — dR} (F _j ), the control processing unit 119 performs the test output from the speaker 130 _L at the start of step S24. towards audio, than test sound output from the speaker 130 _R, it identifies the phase is delayed in supposition listening position.

When the direction of the phase difference φ _j is specified in this way, step S24 ends. Then, the process proceeds to step S25 in FIG.

In step S25, the level for accuracy confirmation of the phase difference φ _j having the absolute value calculated in step S23 and having the direction specified in step S24 is acquired. When acquiring the level for checking accuracy, the control processing unit 119 calculates a phase adjustment parameter value necessary to make up for the phase difference φ _j . In the present embodiment, the speaker 130 output the test sound phase from _R, to change only the phase retardation phi _j from the phase state of the test sound is output from the speaker 130 _R at the beginning of step S25 The phase adjustment parameter value is calculated.

Subsequently, the control processing unit 119 sends the phase adjustment designation PHC _R designating the phase adjustment parameter value calculated this time to the phase adjustment unit 213 _R. In addition, the control processing unit 119 sets the phase adjustment specification PHC _L specifying the phase adjustment parameter value for setting the phase of the test sound output from the speaker 130 _L to the phase state at the start time of the immediately preceding step S24. sent to the adjustment unit 213 _L.

After entering the sound output state by this phase adjustment, the control processing unit 119 collects the level detection result DLD sent from the level detection unit 111 a second predetermined number of times. Then, the control processing unit 119 obtains a new sound collection level A _LRn (F _j ) by calculating the average value of the collected level detection results DLD.

Next, in step S26, the control processing unit 119 determines whether or not the phase difference φ _j has approached 0 within the allowable range. In this determination, the new sound collection level A _LRn (F _j ), the sound collection level A _L (F _j ) and the sound collection level A _R (F _j ) acquired in step S22 are used as described above ( Although the determination can be performed after calculating the expression (1), in the present embodiment, the determination is performed depending on whether the condition expressed by the following expression (2) is satisfied. .
| A _LRn (F _j ) − (A _L (F _j ) + A _R (F _j )) | ≦ Δ _TH (F _j ) (2)

The value Δ _TH (F _j ) is determined in advance based on experiments, simulations, experiences, and the like from the viewpoint of the accuracy of phase correction.

  If the result of the determination in step S26 is negative (step S26: N), the process proceeds to step S27. In step S27, the control processing unit 119 determines whether the phase difference accuracy has been confirmed a predetermined number of times. The “predetermined limit number” is determined in advance based on experiments, simulations, experiences, and the like from the viewpoint of high accuracy of phase correction and speeding up of the phase correction process.

  If the result of the determination in step S27 is negative (step S27: N), the process returns to step S23. And the process of step S23-S27 is repeated until the result of determination in step S26 or step S27 becomes affirmative. At that time, for the second and subsequent steps S23 to S27, the state using the phase adjustment parameter value calculated in step S25 during the previous processing is used as the state at the start of step S23.

If the result of determination in step S26 or step S27 is affirmative (step S26: Y or step S27: Y), the process proceeds to step S28. In this step S28, if a positive result is obtained in step S26 in the first processing in steps S23 to S25, the control processing unit 119 performs correction based on the phase adjustment parameter value calculated in step S25. The phase difference ψ _j is calculated. When the processes in steps S23 to S25 are performed a plurality of times, the control processing unit 119 adds all of the phase differences in the phase adjustment parameter values calculated in the plurality of steps S25, thereby correcting the phase difference to be corrected. ψ _j is calculated.

When the correction target phase difference ψ _j is calculated and the specification of the correction target phase difference ψ _j is completed, the control processing unit 119 sets the test audio signal specifying TSC specifying that the test audio signal TSD is not generated to the test signal generating unit 215. Send to. As a result, the generation of the test audio signal TSD by the test signal generation unit 215 ends.

  When the process of step S28 is thus completed, the process of step S13 is terminated. Then, the process proceeds to step S14 in FIG.

In step S14, the control processing unit 119 determines whether or not the correction target phase difference has been specified for all the test audio frequencies F _j (j = 1 to N). If the result of this determination is negative (step S14: N), the process proceeds to step S15.

In step S15, the control processing unit 119 sets the next test audio frequency as the measurement frequency. In the present embodiment, when the measurement frequency up to that time is the test audio frequency F _k (k = 1 to (N−1)), the test audio frequency F _{k + 1} is set as the measurement frequency. It has become. Then, the process returns to step S13.

Subsequently, the processes in steps S13 to S15 are repeated until the result of the determination in step S14 becomes affirmative. When the correction target phase difference is specified for all the test audio frequencies F _j (j = 1 to N) and the determination result in step S14 is affirmative (step S14: Y), the process proceeds to step S16. .

In step 16, based on the identified correction target phase difference ψ _j (j = 1 to N), the control processing unit 119 compensates for the correction target phase difference ψ _j for each of the signals of the frequency F _j. An adjustment parameter value is calculated. In the present embodiment, in principle, and it calculates a phase adjustment parameter value for the phase correction of the sound output from the speaker 130 _R. As shown in FIG. 2, the vehicle CR is the right steering wheel, and the phase at the assumed listening position of the sound output from the speaker 130 _R is at the assumed listening position of the sound output from the speaker 130 _L. This is because it is ahead of the phase. If there is a possibility that the phase correction only by the phase adjustment of the sound output from the speaker 130 _R may cause an adverse effect, the phase adjustment parameter value for the phase correction of the sound output from the speaker 130 _{L is} exceptionally matched. To calculate.

Returning to FIG. 6, next, in step S <b> 17, the control processing unit 119 changes the phase adjustment designation PHC _R in which the phase adjustment parameter value calculated in step S <b> 16 is designated for the sound output from the speaker 130 _R to the phase adjustment. Send to part 213 _R. Incidentally, in step S16, when it is calculated to fit the phase adjustment parameter value for the phase correction of the sound output from the speaker 130 _L is a phase adjustment parameter value calculated for the sound output from the speaker 130 _L The designated phase adjustment designation PHC _L is sent to the phase adjustment unit 213 _L.

Thus, the setting of the phase adjustment parameter value for phase correction to the phase adjustment unit 213 _R (and the phase adjustment unit 213 _{L as} necessary) is completed. Thereafter, the control processing unit 119 issues a volume adjustment command VLC specifying the output volume before the start of the above-described phase correction process to the volume adjustment unit 242. Then, the control processing unit 119, and sends the selection specifying SLC _L indicating to select the separation channel signal SCD _L to the signal selection section 212 _L, designated selection to the effect that selects the separation channel signal SCD _R SLC _R signals The data is sent to the selection unit 212 _R.

  When the above process is performed and the process of step S17 is completed, the phase correction process is completed. After the phase correction is completed in this way, when the user inputs a reproduction command designating audio content to the operation input unit 160, this is sent to the control processing unit 119 as operation input data IPD. When receiving the reproduction command, the control processing unit 119 issues a reading command CSL to the sound source unit 120 and controls reading of the content data CTD. Under such control, the content data CTD read from the sound source unit 120 is sent to the digital processing unit 112 (see FIG. 1).

In the digital processing unit 112, the channel separation unit 211 receives the content data CTD. Channel separating unit 211 which has received the content data CTD the content data CTD, L in two-channel stereo system, corresponding to the R channel two separate channel signals SCD _L, separating the SCD _R. The separated channel signals SCD _L and SCD _R separated in this way are sent to the phase adjustment units 213 _L and 213 _R as the signals SLD _L and SLD _R after passing through the signal selection units 212 _L and 212 _R ( (See FIG. 4).

The phase adjustment units 213 _L and 213 _R perform phase adjustment on the signals SLD _L and SLD _R according to the phase adjustment parameter values designated by the phase adjustment designations PHC _L and PHC _R sent from the control processing unit 119. Then, the phase adjustment results are sent to the analog processing unit 113 as phase adjustment signals AOD _L and AOD _R (see FIG. 4).

Thereafter, the phase adjustment signals AOD _L and AOD _R are converted into analog signals by the DA converter 241. Subsequently, the volume adjustment unit 242 performs volume adjustment processing on the analog signal from the DA conversion unit 241 in accordance with the volume adjustment command VLC from the control processing unit 119, and sends it to the power amplification unit 243 as a volume adjustment signal (FIG. 5).

Receiving the volume adjustment signal, the power amplifier 243 power-amplifies the volume adjustment signal to generate audio output signals AOS _L and AOS _R , and sends them to the speakers 130 _L and 130 _R. Then, the speakers 130 _L and 130 _R reproduce and output audio in accordance with the phase-corrected audio output signals AOS _L and AOS _R (see FIG. 5).

As described above, in the present embodiment, the first test sound output from the speaker 130 _L, the second test sound output from the speaker 130 _R based on each of a plurality of types of single-frequency test sound signals, In addition, the level of the synthesized voice of the first and second test voices output simultaneously from the speakers 130 _L and 130 _R is detected. Based on these detection results, the absolute value of the phase difference between the first test sound and the second test sound at the assumed listening position is calculated. Subsequently, the level of the synthesized speech when the phase of the first speech is delayed by an amount corresponding to the absolute value, and the level of the synthesized speech when the phase of the second speech is delayed by an amount corresponding to the absolute value Is detected, and both levels are compared to identify the direction of the phase difference. Then, based on the calculated absolute value of the phase difference and the direction of the specified phase difference, the phase of the sound output from the speakers 130 _L and 130 _R is corrected.

  Therefore, according to the present embodiment, it is possible to accurately perform the phase correction for the low-frequency component with a simple configuration that does not require accurate synchronization between the test sound generation unit and the sound collection unit.

  In the present embodiment, after the test voice is collected, the level detection is performed after selecting a signal component near the frequency of the test voice. For this reason, the noise component contained in the sound collection result can be effectively removed, and the level detection with high accuracy can be performed.

  Further, in the present embodiment, after the test voice is collected, cumulative addition of the collected sound waves is performed for each period length of the test voice frequency. For this reason, the noise component contained in the sound collection result can be effectively reduced, and the level detection with high accuracy can be performed.

[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 effective value of the sound collection result signal is detected as the signal level. However, the maximum amplitude value of the sound collection result signal may be detected as the signal level.

  In the above embodiment, the test signal generator for generating the test audio signal is arranged in the digital processing unit. On the other hand, the test sound data may be read from the sound source unit. For example, when the audio device is a device that reproduces audio content recorded on a recording medium such as a DVD, test audio may be recorded on the storage medium as audio content. In this case, the test signal generation unit and the signal selection unit in the digital processing unit can be omitted.

In the above embodiment, the phase difference at the assumed listening position between the sound component output from the speaker 130 _L and the sound component output from the speaker 130 _R is eliminated for the sound component in the predetermined frequency range in the low frequency range. Phase correction was performed. On the other hand, you may make it perform the phase correction which produces a desired phase difference for every frequency in the said predetermined frequency range.

Further, in the above embodiment, when the correction target phase difference is specified and the phase adjustment result does not satisfy the condition of the expression (2), the sound collection level A _L (F _j ) acquired in step S22. And the sound collection level A _R (F _j ) are used to calculate the direction of the phase difference and to determine again whether or not the condition of the expression (2) is satisfied. On the other hand, when the result of the phase adjustment does not satisfy the condition of the expression (2), the sound collection level A _L (F _j ) and the sound collection level A _R (F _j ) are newly acquired, You may make it perform the determination again about whether the conditions of 2) are satisfy | filled.

  In the above embodiment, when the correction target phase difference is specified and the phase adjustment result does not satisfy the condition of the expression (2), the phase adjustment is repeated up to a predetermined limit number. The phase adjustment may be repeated a predetermined number of times without considering the condition of equation (2).

  In the above embodiment, the all-pass filter is used for phase adjustment. However, a delay element may be used instead of the all-pass filter, or the all-pass filter and the delay element are used in combination. Also good.

  In the above embodiment, the time alignment unit is not provided. However, the time alignment unit may be further provided, and the phase correction process may be performed after the time alignment process.

  Further, in the above embodiment, the present invention is applied to an audio apparatus that employs a two-channel stereo system, but the present invention is also applied to an audio apparatus that employs a multi-channel surround system such as a 5.1 channel surround system. Can do.

  In the above embodiment, the present invention is applied to an acoustic device mounted on a vehicle. However, the present invention is also applied to an acoustic device mounted on a moving body other than the vehicle and an acoustic device installed in a home. can do.

  In addition, a part or all of the level detection unit, the digital processing unit, and the control processing unit in the above embodiment is configured as a computer system including a central processing unit (CPU: Central Processor Unit) and a DSP (Digital Signal Processor). This function can also be realized by executing a program. These programs 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 distributed via a network such as the Internet. Good.

DESCRIPTION OF SYMBOLS 100 ... Acoustic apparatus 119 ... Control processing part (calculation means, control means)
130 _L ... Speaker (first speaker)
130 _R ... Speaker (second speaker)
140 ... Sound collecting unit (sound collecting means)
213 _L ... Phase adjustment unit (part of adjustment means, all-pass filter means)
213 _R ... Phase adjustment unit (part of adjustment means, all-pass filter means)
215... Test signal generation unit (generation means)
251... Variable band pass filter section (band pass filter means)
252... Signal level detection unit (detection means)

Claims (12)

An acoustic device that outputs reproduced sound from a plurality of speakers including a first speaker and a second speaker,
Generating means for generating at least one single frequency test audio signal;
Sound collecting means arranged at an assumed listening position and collecting reproduced sound reproduced and output from the plurality of speakers based on the test sound signal;
Detecting means for detecting a signal level of a sound collection result obtained by the sound collecting means;
For each type of test audio signal, the detection result of the first sound from the first speaker by the detection means, the detection result of the second sound from the second speaker by the detection means, and the first Calculating means for calculating an absolute value of a phase difference between the first sound and the second sound at the assumed listening position based on a detection result by the detecting means for a synthesized sound of the sound and the second sound;
Control means for controlling phase adjustment of the first sound and the second sound based on a calculation result by the calculation means;
Adjusting means for performing phase adjustment in accordance with phase adjustment control by the control means;
An acoustic device comprising:   The acoustic device according to claim 1, wherein each of the single frequencies is a frequency equal to or lower than a predetermined frequency.   Band-pass filter means that is disposed between the sound pickup means and the detection means, and selectively passes a frequency component in the vicinity of the frequency of the test sound signal in the signal of the sound pickup result by the sound pickup means. The acoustic device according to claim 1, wherein The detection means includes
While accumulating a predetermined number of signal waveforms of the sound collection results for each cycle time of the test audio signal,
Based on the result of the cumulative addition, the signal level of the sound collection result by the sound collection means is detected.
The acoustic device according to any one of claims 1 to 3, wherein The control means includes
The detection result by the detection means for the synthesized voice when the phase delay corresponding to the absolute value of the phase difference calculated by the calculation means is given to the first voice, and the phase delay is given to the second voice. In the case where the phase delay is not given to either the first sound or the second sound based on the magnitude relationship between the synthesized sound and the detection result of the detection means in the case where To determine whether the phase is advanced or delayed with respect to the phase of the second sound,
Based on the result of the determination and the absolute value of the phase difference calculated by the calculation means, the phase adjustment control is performed so that the relationship between the phase of the first sound and the phase of the second sound is a predetermined relationship. To the adjustment means,
The acoustic device according to any one of claims 1 to 4, wherein   The acoustic device according to claim 5, wherein the predetermined relationship is a relationship in which there is no phase difference between the first sound and the second sound at the assumed listening position.   The acoustic device according to claim 5, wherein the control unit repeats execution of a new phase adjustment control based on a calculation result by the calculation unit after the phase adjustment control a predetermined number of times.   The control means is based on a calculation result by the calculation means after the phase adjustment control until the relationship between the phase of the first sound and the phase of the second sound matches the predetermined relationship within an allowable range. The acoustic device according to claim 5 or 6, wherein execution of new phase adjustment control is repeated up to a predetermined maximum number of times.   9. The adjustment unit according to claim 1, further comprising an all-pass filter unit having a constant amplitude frequency characteristic and a phase frequency characteristic changing according to a phase adjustment control by the control unit. The acoustic device according to item. A plurality of speakers, each including a first speaker and a second speaker, for outputting reproduced sound; generating means for generating at least one type of single-frequency test sound signal; and the test sound signal disposed at an assumed listening position A phase correction used in an acoustic device comprising: sound collection means for collecting reproduced sound reproduced and output from the plurality of speakers based on the above; and detection means for detecting a signal level of a sound collection result by the sound collection means A method,
A first acquisition step of acquiring, for each type of the test audio signal, a first detection result by the detection means for the first audio from the first speaker;
A second acquisition step of acquiring a detection result by the detection means for the second sound from the second speaker;
A third acquisition step of acquiring a detection result by the detection means for a synthesized voice of the first voice and the second voice;
A calculation step of calculating an absolute value of a phase difference between the first sound and the second sound at the assumed listening position based on the acquisition results in the first to third acquisition steps;
A control step of controlling phase adjustment of the first voice and the second voice based on the calculation result in the calculation step;
A phase correction method comprising:   A phase correction program for causing a calculation means to execute the phase correction method according to claim 10.   12. A recording medium in which the phase correction program according to claim 11 is recorded so as to be readable by a calculation means.

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