JP6115161B2 - Audio equipment, control method and program for audio equipment - Google Patents

Description

  The present invention relates to a technical field for automatically correcting sound field characteristics in an audio system including a plurality of speakers.

  This type of technique is proposed in Patent Document 1, for example. In Patent Document 1, the same equalizer gain value (a parameter for adjusting a frequency characteristic by an equalizer, in other words, an equalizer coefficient) is determined for a channel whose phases should be matched among a plurality of channels. There has been proposed a technique for reducing the influence of phase mismatch between the two.

JP 2002-330499 A

  Incidentally, there are several methods (frequency characteristic correction methods) for correcting the frequency characteristics for each channel. For example, a frequency characteristic correction method for matching all phases in a plurality of channels, a frequency characteristic correction method for matching phases in a pair of left and right channels, and a frequency characteristic of each of a plurality of channels are individually corrected. For this purpose, a frequency characteristic correction method can be considered. The optimum correction method to be applied among such frequency characteristic correction methods differs depending on the viewing environment (sound field environment) of the user.

  However, in the conventional technology, the applied frequency characteristic correction method is fixed, or the user manually selects and sets the frequency characteristic correction method. In the former case, the fixed frequency characteristic correction method may not be optimal for the user's viewing environment. In the latter case, in order to find the optimum frequency characteristic correction method for the user's viewing environment, the user had to repeat the automatic sound field correction many times by changing the frequency characteristic correction method. Needed. Actually, it has been difficult for the user to accurately grasp the viewing environment and to properly understand the prepared frequency characteristic correction method, and therefore, in many cases, the optimum frequency characteristic correction method cannot be selected.

  The above-mentioned thing is mentioned as an example as a subject which the present invention tends to solve. It is an object of the present invention to provide an audio device or the like that can automatically select and apply a frequency characteristic correction method that is optimal for a user's viewing environment.

  In the invention according to the claim, an acoustic device capable of outputting a plurality of channels of sound includes a sound collection unit that collects measurement signals output from the plurality of channels to be subjected to frequency correction, and the sound collection unit. The storage unit for storing the frequency amplitude level for each frequency band of the sound collection data collected by the above and the frequency amplitude level stored in the storage unit are compared, and 1 is set in advance according to the comparison result. Or a processing unit that selects a correction group including a plurality of channels and corrects the frequency characteristics of the plurality of channels in units of the selected correction group.

  Further, in the invention described in the claims, the control method executed by the acoustic device capable of outputting sound of a plurality of channels is a collection method for collecting the measurement signals output from the plurality of channels to be subjected to frequency correction. Comparing the frequency amplitude level stored in the storage step with the storage step for storing the frequency amplitude level for each frequency band of the sound collection data collected by the sound collection step, and the comparison result And a processing step of selecting a correction group composed of one or more preset channels and correcting the frequency characteristics of the plurality of channels in the selected correction group unit. .

  According to the invention described in the claims, a program that is capable of outputting sound of a plurality of channels and that is executed by an acoustic device having a computer is output from the plurality of channels that are subjected to frequency correction to the computer. The sound collecting means for collecting the measurement signal, the storage means for storing the frequency amplitude level for each frequency band of the sound collection data collected by the sound collecting means, and the frequency amplitude level stored by the storage means are compared. And a processing unit that selects a correction group including one or a plurality of channels set in advance according to the comparison result, and corrects the frequency characteristics of the plurality of channels in the selected unit of the correction group. It is characterized by making it.

It is a block diagram which shows the structure of an audio system provided with the audio equipment of a present Example. It is a block diagram which shows the internal structure of the signal processing circuit shown in FIG. It is a block diagram which shows the structure of the signal processing part shown in FIG. It is a block diagram which shows the structure of the coefficient calculating part shown in FIG. FIG. 5 is a block diagram illustrating configurations of a frequency characteristic correction method selection unit, a frequency characteristic correction unit, an inter-channel level correction unit, and a delay characteristic correction unit illustrated in FIG. 4. It is a figure which shows the example of arrangement | positioning of the speaker in a certain sound field environment. It is a figure for demonstrating an example of a frequency characteristic correction system. It is a flowchart which shows the main routine of an automatic sound field correction process. It is a flowchart which shows a frequency characteristic correction system selection process. It is a figure for demonstrating the method of the frequency characteristic comparison between channels. It is a flowchart which shows a frequency characteristic correction process. It is a flowchart which shows the level correction process between channels. It is a flowchart which shows a delay characteristic correction process.

  In one aspect of the present invention, an acoustic device capable of outputting sound of a plurality of channels includes a sound collection unit that collects measurement signals output from the plurality of channels to be subjected to frequency correction, and the sound collection unit. The storage unit for storing the frequency amplitude level for each frequency band of the sound collection data collected by the above and the frequency amplitude level stored in the storage unit are compared, and 1 is set in advance according to the comparison result. Or a processing unit that selects a correction group including a plurality of channels and corrects the frequency characteristics of the plurality of channels in units of the selected correction group.

  The above acoustic device is preferably applied to an audio system including a plurality of speakers. The sound collection unit collects measurement signals output from a plurality of channels, the storage unit stores the frequency amplitude level for each frequency band of the sound collection data collected by the sound collection unit, and the processing unit includes: The frequency amplitude levels stored in the storage unit are compared, and a correction group consisting of one or more preset channels is selected according to the comparison result. Then, the processing unit corrects the frequency characteristics of the plurality of channels in units of the selected correction group. Here, the “frequency characteristic” means not a frequency phase characteristic but a frequency amplitude characteristic. Further, the processing unit sets, for example, a parameter (equalizer gain value / equalizer coefficient) used in the equalizer.

  According to the above acoustic apparatus, the frequency characteristics of a plurality of channels are corrected in units of correction groups corresponding to the analysis result of the frequency characteristics in the user viewing environment. This makes it possible to automatically set a frequency characteristic correction method that is optimal for the user's viewing environment. For example, it is possible to automatically set a frequency characteristic correction method that optimizes the user viewing environment in terms of the balance between timbre uniformity and sound image localization.

  In addition, according to the above-described audio equipment, since the optimum frequency characteristic correction method is automatically set, the user can change the frequency characteristic correction method to find the optimum frequency characteristic correction method for the viewing environment, and perform automatic sound field correction. There is no need to repeat the above. In addition, the user does not need to accurately grasp the viewing environment or properly understand the prepared frequency characteristic correction method.

  In one aspect of the acoustic device, the processing unit selects the correction group based on a correlation between the frequency amplitude levels between left and right channels and / or front and rear channels in the plurality of channels, and the correction group The frequency characteristics are corrected based on the sound collection data collected by the sound collection unit for the measurement signal output in units. Thereby, the correction group according to the acoustic characteristic of the left-right direction and / or the acoustic characteristic of the front-back direction in a user's viewing environment can be selected.

  In another aspect of the above acoustic device, the processing unit may determine that there is a correlation between the frequency amplitude levels between the left and right channels and that there is no correlation between the frequency amplitude levels between the front and rear channels. Corrects the frequency characteristics based on the sound collection data collected by the sound collection unit for the measurement signals output simultaneously from the left and right channels. According to this aspect, in a viewing environment in which left and right acoustic characteristics are uniform, the phases of a pair of left and right channels can be appropriately matched.

  Note that “there is a correlation between the frequency amplitude levels between the left and right channels” means that the variation in the frequency amplitude levels between the left and right channels is small, in other words, the frequency amplitude levels between the left and right channels are similar. Conversely, “there is no correlation between the frequency amplitude levels between the left and right channels” means that the frequency amplitude levels vary greatly between the left and right channels, in other words, the frequency amplitude levels between the left and right channels are not similar. . Whether such “correlation” exists is determined by comparing the difference between the frequency amplitude levels for each frequency band with a predetermined threshold value between the left and right channels. The same applies to the frequency amplitude level between the front and rear channels.

  The “left and right channels” mean a set of channels that are paired on the left and right sides in a plurality of channels. In addition, the “front and back channel” includes any one channel or any left and right channels and one channel or left and right channels positioned in front of or behind the one channel or the left and right channels in a plurality of channels. Means set.

  In another aspect of the above acoustic device, the processing unit may determine that there is a correlation between the frequency amplitude levels between the left and right channels and a correlation between the frequency amplitude levels between the front and rear channels. Corrects the frequency characteristics based on the sound collection data collected by the sound collection unit for the measurement signals output simultaneously from all of the plurality of channels. According to this aspect, it is possible to appropriately match the phases of all channels in a viewing environment where the left and right acoustic characteristics are aligned.

  In another aspect of the above acoustic device, the processing unit may output a measurement signal output from each of the plurality of channels when it is determined that there is no correlation between the frequency amplitude levels between the left and right channels. The frequency characteristic is corrected based on the sound collection data collected by the sound collection unit. According to this aspect, in a viewing environment where the left and right acoustic characteristics are not uniform, the frequency characteristics of each channel can be individually corrected appropriately without matching the phases of the channels.

  In another aspect of the present invention, a control method executed by an acoustic device that enables sound output of a plurality of channels is a sound collection step of collecting measurement signals output from the plurality of channels that are subjected to frequency correction. And a storage step for storing the frequency amplitude level for each frequency band of the sound collection data collected by the sound collection step, and the frequency amplitude level stored by the storage step, and according to the comparison result And a processing step of selecting a preset correction group including one or a plurality of channels and correcting the frequency characteristics of the plurality of channels in units of the selected correction group.

  In another aspect of the present invention, a program that is capable of outputting a plurality of channels of audio and that is executed by an audio device having a computer is output from the plurality of channels that are subjected to frequency correction. The sound collecting means for collecting the measurement signal, the storage means for storing the frequency amplitude level for each frequency band of the sound collection data collected by the sound collecting means, and the frequency amplitude level stored by the storage means are compared. And a processing unit that selects a correction group including one or a plurality of channels set in advance according to the comparison result, and corrects the frequency characteristics of the plurality of channels in the selected unit of the correction group. Let

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[System configuration]
Below, the Example of the audio equipment which concerns on a present Example is described with reference to drawings.

  FIG. 1 is a block diagram illustrating a configuration of an audio system 100 including an audio device according to the present embodiment.

  In FIG. 1, the audio system 100 includes digital audio signals SFL, SFR, SC from a sound source 1 such as a DVD (Digital Video Disc or Digital Versatile Disc) or a BD (Blu-ray Disc) player through a signal transmission path of a plurality of channels. , SSL, SSR, SWF, SSBL and SSBR are provided with a signal processing circuit 2 and a measurement signal generator 3.

  The audio system includes a signal transmission path of a plurality of channels. In the following description, each channel may be expressed as “FL channel”, “FR channel”, or the like. In addition, when referring to all of a plurality of channels in the representation of signals and components, the suffixes of reference numerals may be omitted. Further, when referring to signals and components of individual channels, subscripts for identifying the channels are attached to the reference numerals. For example, “digital audio signal S” means digital audio signals SFL to SSBR of all channels, and “digital audio signal SFL” means digital audio signals of only the FL channel. .

  Furthermore, the audio system 100 includes D / A converters 4FL to 4SBR that convert the digital outputs DFL to DSBR processed for each channel by the signal processing circuit 2 into analog signals, and these D / A converters 4FL to 4SBR. Amplifiers 5FL to 5SBR for amplifying each analog audio signal output from. The analog audio signals SPFL to SPSBR amplified by these amplifiers 5 are supplied to a plurality of speakers 6FL to 6SBR arranged in a listening room 7 as illustrated in FIG.

  The audio system 100 also includes a microphone 8 that collects the reproduced sound at the listening position RV, an amplifier 9 that amplifies the sound collection signal SM output from the microphone 8, and an output of the amplifier 9 as digital sound collection data DM. And an A / D converter 10 that converts the signal and supplies it to the signal processing circuit 2.

  Here, the audio system 100 reproduces only the so-called deep bass sounds with all-band speakers 6FL, 6FR, 6C, 6SL, 6SR, 6SBL, and 6SBR having frequency characteristics that can be reproduced over almost the entire audio frequency band. A sound field space with a sense of presence is provided to the listener at the listening position RV by ringing the speaker 6WF dedicated to low-frequency reproduction having the frequency characteristics described above.

  For example, as shown in FIG. 6, each speaker is arranged in accordance with ITU-R recommendation (ITU-R BS775-1), in front of the listening position RV, two front left and right channel speakers 6FL and 6FR and a center speaker. 6C is arranged. Further, surround speakers 6SL and 6SR with two channels on the left and right are arranged behind the listening position RV, and surround speakers 6SBL and 6SBR with two channels on the left and right are arranged behind them. In addition, a subwoofer 6WF dedicated to low frequency reproduction is arranged at an arbitrary position. The audio device provided in the audio system 100 supplies the eight audio speakers 6FL to 6SBR with the analog audio signals SPFL to SPSBR in which the frequency characteristics, the signal level of each channel, and the signal arrival delay characteristics are corrected, and causes them to ring. Realize a realistic sound field space.

  In the audio system 100 as described above, the combination of the FL channel and the FR channel, the combination of the SL channel and the SR channel, and the combination of the SBL channel and the SBR channel correspond to an example of the “left and right channels” in the present invention. To do. On the other hand, the combination of the C channel and the FL and FR channels, the combination of the FL and FR channels with the SL and SR channels, the combination of the SL and SR channels with the SBL and SBR channels, and the like are referred to as “front and back channels in the present invention. Is equivalent to an example.

  The signal processing circuit 2 is formed by a digital signal processor (DSP) or the like, and is roughly composed of a signal processing unit 20 and a coefficient calculation unit 30 as shown in FIG. The signal processing unit 20 receives digital audio signals of a plurality of channels from the sound source 1 that reproduces DVD, BD, and other various music sources, and performs frequency characteristic correction, level correction, and delay characteristic correction for each channel, and outputs a digital output signal. DFL to DSBR are output. The coefficient calculation unit 30 receives a signal collected by the microphone 8 as digital sound collection data DM, and coefficient signals SF1 to SF8, SG1 to SG8, SDL1 to SDL8 for frequency characteristic correction, level correction, and delay characteristic correction. Are respectively generated and supplied to the signal processing unit 20. Based on the sound collection data DM from the microphone 8, the signal processing unit 20 performs appropriate frequency characteristic correction, level correction, and delay characteristic correction, so that an optimum signal is output from each speaker 6.

  As shown in FIG. 3, the signal processing unit 20 includes a graphic equalizer GEQ, interchannel attenuators ATG1 to ATG8, and delay circuits DLY1 to DLY8. On the other hand, as shown in FIG. 4, the coefficient calculation unit 30 includes a system controller MPU, a frequency characteristic correction unit 11, an interchannel level correction unit 12, a delay characteristic correction unit 13, and a frequency characteristic correction method selection unit 14. It has. The frequency characteristic correction unit 11, the interchannel level correction unit 12, the delay characteristic correction unit 13, and the frequency characteristic correction method selection unit 14 are formed by a DSP.

  The frequency characteristic correction unit 11 adjusts the frequency characteristics of the equalizers EQ1 to EQ8 corresponding to the respective channels of the graphic equalizer GEQ, the interchannel level correction unit 12 adjusts the attenuation rate of the interchannel attenuators ATG1 to ATG8, and the delay characteristic correction unit. 13 is configured to perform appropriate sound field correction by adjusting the delay times of the delay circuits DLY1 to DLY8.

  Here, the equalizers EQ1 to EQ5, EQ7, and EQ8 of each channel are configured to perform frequency characteristic correction for each of a plurality of bands. That is, the audio frequency band is divided into, for example, nine bands (the center frequency of each band is set to f1 to f9), and the coefficient of the equalizer EQ is determined for each band to perform frequency characteristic correction. Note that the equalizer EQ6 is configured to adjust the frequency characteristic of the low frequency band.

  The audio system 100 has two modes of operation modes: an automatic sound field correction mode and a sound source signal reproduction mode. The automatic sound field correction mode is an adjustment mode that is performed prior to signal reproduction from the sound source 1, and performs automatic sound field correction for the environment in which the system 100 is installed. Thereafter, the sound signal from the sound source 1 such as a DVD is reproduced in the sound source signal reproduction mode. The present invention mainly relates to correction processing in an automatic sound field correction mode.

  Referring to FIG. 3, the equalizer EQ1 of the FL channel is supplied with a switch element SW12 for controlling on / off of the input of the digital audio signal SFL from the sound source 1 and an input of the measurement signal DN from the measurement signal generator 3. A switch element SW11 for on / off control is connected, and the switch element SW11 is connected to the measurement signal generator 3 via the switch element SWN.

  The switch elements SW11, SW12, and SWN are controlled by the system controller MPU formed by the microprocessor shown in FIG. 4, and when the sound source signal is reproduced, the switch element SW12 is turned on (conductive) and the switch elements SW11 and SWN are turned off (non-conductive). When the sound field is corrected, the switch element SW12 is turned off and the switch elements SW11 and SWN are turned on.

  An interchannel attenuator ATG1 is connected to the output contact of the equalizer EQ1, and a delay circuit DLY1 is connected to the output contact of the interchannel attenuator ATG1. The output DFL of the delay circuit DLY1 is supplied to the D / A converter 4FL in FIG.

  Other channels have the same configuration as the FL channel, and switch elements SW21 to SW81 corresponding to the switch element SW11 and switch elements SW22 to SW82 corresponding to the switch element SW12 are provided. Subsequently to these switch elements SW21 to SW82, equalizers EQ2 to EQ8, inter-channel attenuators ATG2 to ATG8, and delay circuits DLY2 to DLY8 are provided, and outputs DFR to DSBR of the delay circuits DLY2 to DLY8 are shown in FIG. To the D / A converters 4FR to 4SBR.

  Further, the inter-channel attenuators ATG1 to ATG8 change the attenuation rate in the range from 0 dB to the minus side in accordance with the adjustment signals SG1 to SG8 from the interchannel level correction unit 12. The delay circuits DLY1 to DLY8 of each channel change the delay time of the input signal according to the adjustment signals SDL1 to SDL8 from the phase characteristic correction unit 13.

  FIG. 5 is a block diagram illustrating the configuration of the frequency characteristic correction method selection unit 14, the frequency characteristic correction unit 11, the interchannel level correction unit 12, and the delay characteristic correction unit 13 illustrated in FIG.

  The frequency characteristic correction method selection unit 14 has a function of determining a frequency characteristic correction method from the analysis results of the frequency characteristics of all channels. As shown in FIG. 5A, the frequency characteristic correction method selection unit 14 includes a bandpass filter 14a, a coefficient table 14b, a correction method determination unit 14c, and a memory 14d.

  The bandpass filter 14a is composed of a plurality of narrowband digital filters that pass the nine bands set in the equalizers EQ1 to EQ8, and the sound collection data DM from the A / D converter 10 is converted to frequencies f1 to f1. By discriminating into 9 frequency bands centered on f9, data [PxJ] indicating the level of each frequency band is supplied to the correction method determination unit 14c. “X” represents channel numbers 1 to 8, and “J” represents frequency band numbers 1 to 9 (hereinafter the same). The frequency discrimination characteristic of the band pass filter 14a is set by filter coefficient data stored in advance in the coefficient table 14b.

  The correction method determination unit 14c receives the data [PxJ] for each channel from the bandpass filter 14a and temporarily stores it in the memory 14d. The correction method determination unit 14c compares the data [PxJ] between the left and right channels and the front and rear channels in a state where the data [PxJ] of all the channels is stored in the memory 14d, and determines the frequency characteristic correction method based on the result. decide. Then, the correction method determination unit 14 c supplies a correction method setting signal ST corresponding to the determined frequency characteristic correction method to the frequency characteristic correction unit 11.

  The frequency characteristic correction unit 11 has a function of adjusting the frequency characteristic of each channel so as to be a desired characteristic. As shown in FIG. 5B, the frequency characteristic correction unit 11 includes a bandpass filter 11a, a coefficient table 11b, a gain calculation unit 11c, a coefficient determination unit 11d, and a coefficient table 11e.

  The band pass filter 11a is composed of a plurality of narrow band digital filters that pass the nine bands set in the equalizers EQ1 to EQ8, and the sound collection data DM from the A / D converter 10 is converted to frequencies f1 to f1. By discriminating into nine frequency bands centered on f9, data [PxJ] indicating the level of each frequency band is supplied to the gain calculation unit 11c. The frequency discrimination characteristic of the bandpass filter 11a is set by filter coefficient data stored in advance in the coefficient table 11b.

  Based on the correction method setting signal ST supplied from the frequency characteristic correction method selection unit 14 and the data [PxJ] indicating the level for each band, the gain calculation unit 11c performs equalizers EQ1 to EQ1 during automatic sound field correction. The gain (gain) of EQ8 is calculated for each frequency band, and the calculated gain data [GxJ] is supplied to the coefficient determination unit 11d. That is, by applying the data [PxJ] to the transfer functions of the equalizers EQ1 to EQ8 that are known in advance, the gain (gain) for each frequency band of the equalizers EQ1 to EQ8 is calculated backward.

  The coefficient determination unit 11d generates filter coefficient adjustment signals SF1 to SF8 for adjusting the frequency characteristics of the equalizers EQ1 to EQ8 under the control of the system controller MPU shown in FIG. The coefficient determination unit 11d reads out filter coefficient data for adjusting the frequency characteristics of the equalizers EQ1 to EQ8 from the coefficient table 11e using the gain data [GxJ] for each frequency band supplied from the gain calculation unit 11c, and this filter coefficient data The frequency characteristics of the equalizers EQ1 to EQ8 are adjusted by the filter coefficient adjustment signals SF1 to SF8.

  That is, filter coefficient data for variously adjusting the frequency characteristics of the equalizers EQ1 to EQ8 is stored in advance in the coefficient table 11e as a look-up table, and the coefficient determination unit 11d performs a filter corresponding to the gain data [GxJ]. The coefficient data is read, and the read filter coefficient data is supplied as filter coefficient adjustment signals SF1 to SF8 to the equalizers EQ1 to EQ8, thereby adjusting the frequency characteristics for each channel.

  The filter coefficient adjustment signal SF (SF1 to SF8) described above is a signal for adjusting frequency characteristics by the equalizer EQ (EQ1 to EQ8), and corresponds to an “equalizer coefficient” (in other words, “equalizer gain value”). ”).

  The inter-channel level correction unit 12 has a role of making the sound pressure level of the acoustic signal output through each channel uniform. Specifically, the sound collection data DM obtained when the speakers 6FL to 6SBR are individually ringed by the measurement signal (pink noise) DN output from the measurement signal generator 3 is sequentially input, and the collection is performed. Based on the sound data DM, the level of the reproduced sound of each speaker at the listening position RV is measured.

  A schematic configuration of the inter-channel level correction unit 12 is shown in FIG. The sound collection data DM output from the A / D converter 10 is input to the level detector 12a. The inter-channel level correction unit 12 basically performs level attenuation processing uniformly over the entire band of the signal of each channel, so band division is not necessary. Therefore, the frequency characteristic correction unit of FIG. 11 does not include a bandpass filter as seen in FIG.

  The level detector 12a detects the level of the sound collection data DM, and adjusts the gain so that the output audio signal level for each channel is constant. Specifically, the level detection unit 12a generates a level adjustment amount indicating a difference between the detected sound collection data level and the reference level, and outputs the level adjustment amount to the adjustment amount determination unit 12b. The adjustment amount determination unit 12b generates gain adjustment signals SG1 to SG8 corresponding to the level adjustment amounts received from the level detection unit 12a and supplies them to the inter-channel attenuators ATG1 to ATG8. Each channel attenuator ATG1 to ATG8 adjusts the attenuation rate of the audio signal of each channel according to the gain adjustment signals SG1 to SG5. By adjusting the attenuation factor of the inter-channel level correction unit 12, level adjustment (gain adjustment) between the channels is performed, and the output audio signal level of each channel becomes uniform.

  The delay characteristic correction unit 13 adjusts the signal delay caused by the distance difference between the position of each speaker and the listening position RV, that is, the output signal from each speaker 6 that should be listened to simultaneously by the listener is the listening position RV. It has a role to prevent the time to reach the time from deviating. Therefore, the delay characteristic correcting unit 13 determines the delay characteristic of each channel based on the sound collection data DM obtained when each speaker 6 is individually ringed by the measurement signal DN output from the measurement signal generator 3. Measure and correct the phase characteristics of the sound field space based on the measurement result.

  Specifically, by sequentially switching the switches SW11 to SW82 shown in FIG. 3, the measurement signal DN generated from the measurement signal generator 3 is output from each speaker 6 for each channel, and this is output by the microphone 8. Collect sound and generate corresponding sound collection data DM. If the measurement signal is a pulse signal such as an impulse, for example, the difference between the time when the pulse signal is output from the speaker 8 and the time when the corresponding pulse signal is received by the microphone 8 is the difference between each channel. This is proportional to the distance between the speaker 6 and the microphone 8. Therefore, by combining the delay time of the remaining channels with the delay time of the channel with the largest delay amount among the delay times of each channel obtained from the measurement, the distance difference between the speaker 6 and the listening position RV of each channel is obtained. Can be absorbed. Therefore, the delay between the signals generated from the speakers 6 of each channel can be equalized, and the sounds at the same time on the time axis output from the plurality of speakers 6 reach the listening position RV at the same time.

  FIG. 5D shows the configuration of the delay characteristic correction unit. The delay amount calculation unit 13a receives the sound collection data DM, and calculates a signal delay amount due to the sound field environment for each channel based on the pulse delay amount between the pulse property measurement signal and the sound collection data. The delay amount determination unit 13b receives the signal delay amount for each channel from the delay amount calculation unit 13a and temporarily stores it in the memory 13c. With the signal delay amounts for all the channels calculated and stored in the memory 13c, the adjustment amount determination unit 13b performs other processing simultaneously with the reproduction signal of the channel having the largest signal delay amount reaching the listening position RV. The adjustment amount of each channel is determined so that the reproduction signal of the channel reaches the listening position RV, and the adjustment signals SDL1 to SDL8 are supplied to the delay circuits DLY1 to DLY8 of each channel. Each delay circuit DLY1 to DLY8 adjusts the delay amount according to the adjustment signals SDL1 to SDL8. Thus, the delay characteristic of each channel is adjusted.

  The frequency characteristic correction unit 11 and the frequency characteristic correction method selection unit 14 described above correspond to an example of the “processing unit” in the present invention.

[Automatic sound field correction processing]
Below, the operation | movement of automatic sound field correction | amendment by the audio equipment which has the above-mentioned structure is demonstrated concretely.

  First, as an environment in which the audio system 100 is used, a listener places, for example, a plurality of speakers 6FL to 6SBR in the listening room 7 as shown in FIG. 6 and connects to the audio system 100 as shown in FIG. To do. When the listener operates a remote controller (not shown) provided in the audio system 100 to give an instruction to start automatic sound field correction, the system controller MPU executes automatic sound field correction processing according to this instruction.

  Next, the basic principle of automatic sound field correction according to this embodiment will be described. The graphic equalizer GEQ shown in FIG. 3 is realized by, for example, an IIR (Infinite Impulse Response) filter. When an IIR filter is used, it is advantageous in that a desired frequency characteristic can be obtained with a small amount of calculation and memory. However, since the IIR filter has non-linear phase characteristics, not only the signal amplitude but also the phase changes due to the IIR filter processing. Therefore, depending on the state of phase change that occurs as a side effect of correcting the frequency characteristics of each channel by the equalizer EQ, there may be a case where the phase of the signal does not match between channels, so that accurate sound field reproduction cannot be realized. For example, when the phase of the signal does not match between the left and right channels, the reproduced sound image is not correctly localized at the center of the left and right speakers, so that the listener tends to feel as if there is a sound source at another position on hearing. Therefore, if the left and right speakers are not in phase, the listener may feel uncomfortable that the reproduced sound is generated from an unnatural direction. Since signal phase mismatch between channels occurs only between channels to which different equalizer coefficients are applied, it can be avoided if the equalizer coefficients between channels are the same. However, if the equalizer coefficient between channels is the same, independent frequency characteristic correction cannot be performed for each channel, and the frequency characteristic correction capability is reduced.

  Here, a group of a plurality of channels in which the equalizer coefficients are set to be the same and the phases are matched is referred to as an “in-phase group”. On the other hand, channels that do not belong to any in-phase group are referred to as “independent channels”. Note that the “correction group” in the present invention includes a plurality of channels belonging to the same phase group and / or one channel as an independent channel.

  There is a trade-off relationship between giving priority to matching the frequency characteristics of each channel with desired characteristics or giving priority to matching the phase between channels. Therefore, the priority relationship between the frequency characteristic and the phase match in the frequency characteristic correction processing is determined depending on which channel combination is set as the same phase group. If priority is given to frequency characteristic correction, the number of channels that match the desired frequency characteristic increases, and the timbre of each channel becomes more uniform. On the other hand, when phase matching is prioritized, the number of channels with matching phases increases and the accuracy of sound image localization improves.

  Next, the frequency characteristic correction method according to the present embodiment will be specifically described with reference to FIG. FIG. 7 is a diagram for explaining an example of the frequency characteristic correction method. In FIG. 7, the same phase group is indicated by a broken line.

  FIG. 7A shows a frequency characteristic correction method (hereinafter referred to as “first correction method”) for performing frequency characteristic correction by setting all the channels as independent channels without setting the same phase group. . Basically, according to the first correction method, different equalizer coefficients are set for each channel. In this first correction method, since priority is given to frequency characteristic correction, the frequency characteristic correction capability is higher than those of the second and third correction methods described later. However, in the first correction method, the phase of the signal is likely to be inconsistent among a plurality of channels, and the discomfort of the sound image localization felt by the listener tends to increase. In the first correction method, a correction group in which each channel is set to a separate group is applied.

  FIG. 7B shows a frequency characteristic correction method (hereinafter referred to as “second correction method”) for performing frequency characteristic correction by setting a pair of left and right channels in the same phase group. In the example of the second correction method shown in FIG. 7B, the same equalizer coefficient is set for the FL channel and the FR channel, the same equalizer coefficient is set for the SL channel and the SR channel, and the SBL channel and the SBR channel. Thus, the same equalizer coefficient is set. In such a second correction method, emphasis is placed on the balance between frequency characteristic correction and phase matching, and signal phase matching between a pair of left and right channels is ensured. There is no great sense of incongruity. In addition, as long as the frequency characteristics do not differ greatly between the left and right channels, the correction capability of the frequency characteristics is also high. In the second correction method, the pair of left and right channels are set to the same group (that is, the FL channel and the FR channel are set to the same group, the SL channel and the SR channel are set to the same group, and the SBL is set. The correction group in which the channel and the SBR channel are set to the same group) and only the C channel is set to one group is applied.

  FIG. 7C shows a frequency characteristic correction method (hereinafter referred to as “third correction method”) for performing frequency characteristic correction by setting all channels to one in-phase group. According to the third correction method, the same equalizer coefficient is set for all channels. In this third correction method, since phase matching is prioritized, signal phase matching is ensured between all channels, but the frequency characteristic correction capability is lower than that of the first and second correction methods. In the third correction method, a correction group in which all channels are set to the same group is applied.

By selecting the frequency characteristic correction method as shown in (1) to (3) below from the trade-off relationship between the frequency characteristic correction of each channel and the phase matching between channels, each sound field environment (viewing environment) ) Optimal frequency characteristic correction can be performed.
(1) In a sound field environment where the frequency characteristics of all channels are the same to some extent, the frequency characteristics are corrected by the third correction method with phase matching priority.
(2) In a sound field environment in which only the frequency characteristics of the left and right channels are the same to some extent, the frequency characteristic is corrected by a second correction method that emphasizes the balance between frequency characteristic correction priority and phase matching priority.
(3) In a sound field environment other than (1) and (2), frequency characteristic correction is performed by the first correction method with priority on frequency characteristic correction.

  Consider a case where frequency characteristics are corrected by the second correction method in a sound field environment in which the frequency characteristics of all channels in (1) are somewhat the same. In this case, the frequency characteristics of all the channels are somewhat the same, but not completely the same. As a result of the frequency characteristic correction, the equalizer coefficients differ between the preceding and succeeding channels, and phase mismatch occurs. This phase mismatch may impair the original characteristics of the sound field environment in which the frequency characteristics of all channels are the same to some extent. Therefore, it can be said that it is not appropriate to use the second correction method in such a sound field environment.

  Consider a case where frequency characteristic correction is performed by the second correction method in a sound field environment in which the frequency characteristics of the left and right channels corresponding to the sound field environment other than (1) and (2) in (3) are different. In this case, since the frequency characteristic correction is performed with the pair of left and right channels in the same phase group for the left and right channels having different frequency characteristics, the frequency characteristic correction capability is low. Therefore, the sense of incongruity of the disagreement in the timbres of the left and right channels becomes more conspicuous than the improvement in the accuracy of sound image localization due to the phase matching between the left and right paired channels. Therefore, it can be said that it is not appropriate to use the second correction method in such a sound field environment.

  Next, an outline of the automatic sound field correction process including the selection of the frequency characteristic correction method described above will be described with reference to FIG. FIG. 8 is a flowchart showing the main process of the automatic sound field correction process. This processing is executed by the coefficient calculation unit 30 in the signal processing circuit 2.

  First, in the frequency characteristic correction method selection process in step S10, the frequency characteristic correction method selection unit 14 in the coefficient calculation unit 30 performs a process of determining the frequency characteristic correction method from the analysis results of the frequency characteristics of all channels. Next, in the frequency characteristic correction process in step S20, the frequency characteristic correction unit 11 in the coefficient calculation unit 30 performs a process of adjusting the frequency characteristics of the equalizers EQ1 to EQ8. Next, in the inter-channel level correction process in step S30, the inter-channel level correction unit 12 in the coefficient calculation unit 30 performs a process of adjusting the attenuation rate of the inter-channel attenuators ATG1 to ATG8 provided in each channel. . Next, in the delay characteristic correction process of step S40, the delay characteristic correction unit 13 in the coefficient calculation unit 30 performs a process of adjusting the delay times of the delay circuits DLY1 to DLY8 for all channels.

  Next, the operation of each processing stage will be described in detail. First, with reference to FIG. 9, the frequency characteristic correction method selection process in step S10 of FIG. 8 will be described. FIG. 9 is a flowchart showing frequency characteristic correction method selection processing.

  First, inter-channel level correction processing is performed for all channels (step S101). This process is performed in a state where the frequency characteristics of the equalizer EQ of all the channels are adjusted to be flat (equalizer coefficients are all 0). Specifically, first, in the signal processing unit 20, by turning on the switch SW11 and simultaneously turning off the switch SW12, the measurement signal DN (pink noise) is supplied to one channel (for example, FL channel), The measurement signal DN is output from the speaker 6FL. The microphone 8 collects the signal, and the collected sound data DM is supplied to the interchannel level correction unit 12 in the coefficient calculation unit 30 through the amplifier 9 and the A / D converter 10. In the inter-channel level correction unit 12, the level detection unit 12a detects the sound pressure level of the sound collection data DM and sends it to the adjustment amount determination unit 12b. The adjustment amount determination unit 12b generates an adjustment signal SG1 of the interchannel attenuator ATG1 so as to coincide with a predetermined sound pressure level preset in the target level table 12c, and supplies the adjustment signal SG1 to the interchannel attenuator ATG1. Thus, the level of one channel is corrected so as to coincide with a predetermined level. This process is sequentially performed for each channel, and when the level correction is completed for all channels, the process proceeds to step S102.

  Here, the reason why the level correction is performed in step S101 will be described. When level correction is not performed, there are usually many cases where levels between channels do not match. On the other hand, in the frequency characteristic comparison between channels performed in the subsequent processing, it is determined whether or not the frequency characteristic between channels is different from the level difference of each frequency band between channels. Therefore, if the level correction is not performed, the levels between channels do not match.Therefore, in the frequency characteristic comparison between channels, even if the channels have the same frequency characteristic curve, it is erroneous if the frequency characteristics between channels are different. The possibility of being judged increases. From the above, in order to accurately determine whether or not the frequency characteristics between channels are different in the frequency characteristic comparison between channels performed in the subsequent processing, level correction is performed in advance in step S101.

  Subsequently, in step S102 and subsequent steps, frequency characteristics are analyzed for each channel. Specifically, the measurement signal DN is output from one channel (for example, FL channel) (step S102), and this is collected by the microphone 8 (step S103). The collected sound data DM is supplied to the frequency characteristic correction method selection unit 14 in the signal processing circuit 2, and is frequency-divided by the band pass filter 14a and supplied to the correction method determination unit 14c. Therefore, data [PxJ] indicating the level of each frequency band is supplied to the correction method determination unit 14c. The data [PxJ] supplied to the correction method determination unit 14c is temporarily stored in the memory 14d (step S104). When the frequency characteristic analysis is completed for one channel, it is checked whether the frequency characteristic analysis is completed for all channels (step S105). If the frequency characteristic analysis has not been completed for all channels (step S105: No), the frequency characteristic analysis is similarly performed for the next channel (steps S102 to S104). When the frequency characteristic analysis is completed for all channels (step S105: Yes), the frequency characteristic correction method is then determined from the frequency characteristic analysis result [PxJ] stored in the memory 14d. Comparison of frequency characteristics between channels is performed.

  In the frequency characteristic comparison between channels, first, the frequency characteristic comparison between the left and right channels is performed (step S106). As a result of comparing the frequency characteristics between the left and right channels, if it is determined that the frequency characteristics between the left and right channels are different (step S107: Yes), that is, the frequency characteristics between the left and right channels are not similar (in other words, there is no correlation). If determined, the frequency correction method is set to the first correction method (step S108), and the process returns to the main routine of FIG. On the other hand, when it is determined that the frequency characteristics between the left and right channels are not different (step S107: No), that is, when it is determined that the frequency characteristics between the left and right channels are similar (in other words, there is a correlation) Frequency characteristic comparison between the front and rear channels is performed (step S109).

  If it is determined that the frequency characteristics between the front and rear channels are different as a result of the comparison of the frequency characteristics between the front and rear channels (step S110: Yes), that is, the frequency characteristics between the front and rear channels are not similar (in other words, the correlation is If not, the frequency correction method is set to the second correction method (step S111), and the process returns to the main routine of FIG. On the other hand, when it is determined that the frequency characteristics between the front and rear channels are not different (step S110: No), that is, when it is determined that the frequency characteristics between the front and rear channels are similar (in other words, there is a correlation) The frequency correction method is set to the third correction method (step S112), and the process returns to the main routine of FIG.

  Here, a method of comparing frequency characteristics between channels will be described with reference to FIG. The method shown in FIG. 10 corresponds to an example of a method for determining whether or not there is a correlation in the frequency amplitude level between channels. In FIG. 10, the calculation of the frequency characteristic difference between channels is indicated by a solid arrow.

FIG. 10A is a diagram for explaining an example of frequency characteristic comparison between the left and right channels. First, the absolute value [DyJ] of the difference between the data [PxJ] is calculated between the pair of left and right channels. “X” is channel numbers 1 to 8, “J” is frequency band numbers 1 to 9, and “y” is a channel number. In this example, “y = 1 to 3”, and the absolute value [DyJ] of the difference is calculated between the three left and right channels of the FL channel and the FR channel, the SL channel and the SR channel, and the SBL channel and the SBR channel. The Next, the calculated absolute value the maximum value Dmax of [DyJ], compares the maximum value Dmax and a predetermined threshold value _{TH LR.} When the maximum value Dmax is greater than the threshold value TH _LR, it is determined that the frequency characteristics are different between the left and right channels (step S107 in FIG. 9: Yes), and when the maximum value Dmax is less than or equal to the threshold value TH _LR , the frequency characteristics are determined. Is not different between the left and right channels (step S107 in FIG. 9: No).

FIG. 10B is a diagram for explaining an example of frequency characteristic comparison between the front and rear channels. First, the absolute value [DyJ] of the difference of the data [PxJ] is calculated between the previous and next channels. “X” is channel numbers 1 to 8, “J” is frequency band numbers 1 to 9, and “y” is a channel number. In this example, “y = 1 to 3”, and the C channel and the FL / FR channel, the FL / FR channel and the SL / SR channel, and the SL / SR channel and the SBL / SBR channel between the three front and rear channels, The absolute value [DyJ] of the difference is calculated. More specifically, for the pair of left and right FL / FR channels, the SL / SR channel, and the SBL / SBR channel, not the data [PxJ] but the data [P′zJ] that combines (averages) the frequency characteristics of the pair of left and right channels. ] (See the rectangular area in FIG. 10B). “Z” is a pair of left and right channel numbers, and “z = 1 to 3” in this example. Next, the calculated absolute value the maximum value Dmax of [DyJ], compares the maximum value Dmax and a predetermined threshold value _{TH FB.} When the maximum value Dmax is greater than the threshold value TH _FB, it is determined that the frequency characteristics are different between the front and rear channels (step S110 in FIG. 9: Yes). When the maximum value Dmax is less than the threshold value TH _FB , the frequency characteristics are determined. Is not different between the preceding and following channels (step S110 in FIG. 9: No).

Such frequency characteristic comparison between channels is based on the premise that if there is a part where the level difference is large at any one place in the frequency band between channels, timbre inconsistency will be perceived acoustically between channels. For this reason, a process is employed in which the maximum value Dmax is obtained for the absolute value [DyJ] of the level difference in the frequency band, and the maximum value Dmax is compared with predetermined threshold values TH _LR and TH _FB .

In addition, the maximum value Dmax is obtained separately for each frequency band (for example, three bands of the low band, the middle band, and the high band), and threshold values TH _LR and TH _FB having different values for each band are used, Frequency characteristic comparison may be performed. This is because the influence of the direction of the speaker 6 with respect to the constant pressure wave and the microphone 8 differs depending on the band. Also in this case, if at least one of the obtained maximum values Dmax has a value larger than the thresholds TH _LR and TH _FB , it is determined that the frequency characteristics are different between the left and right channels or between the front and rear channels. .

  In addition, in the above, when comparing the frequency characteristics between the front and rear channels, the three front and rear channels of the C channel and the FL / FR channel, the FL / FR channel and the SL / SR channel, and the SL / SR channel and the SBL / SBR channel are represented. In addition to these, in addition to these, three front and rear channels of FL / FR channel and SBL / SBR channel, C channel and SL / SR channel, and C channel and SBL / SBR channel were used. Further, it may be used.

In the above description, the method of comparing the frequency characteristics between the channels by comparing the maximum value Dmax of the absolute value [DyJ] of the difference with the threshold values TH _LR and TH _FB is exemplified, but this method is used. There is no limitation. If the correlation of frequency characteristics (frequency amplitude level correlation) between channels to be compared is known, various methods other than the method of comparing the maximum value Dmax and the threshold values TH _LR and TH _FB are applied. be able to. In another example, a correlation value of data [PxJ] between channels can be used.

  Next, with reference to FIG. 11, the frequency characteristic correction process in step S20 of FIG. 8 will be described. FIG. 11 is a flowchart showing the frequency characteristic correction process.

  First, it is determined whether or not the same phase group exists (step S201). If it is determined that the same phase group exists (step S201: Yes), the process proceeds to step S202. If the second correction method or the third correction method is set in the frequency characteristic correction method selection process of FIG. 9, it is determined that the same phase group exists. On the other hand, when it is determined that the same phase group does not exist (step S201: No), the process proceeds to step S208. If the first correction method is set in the frequency characteristic correction method selection process of FIG. 9, it is determined that the same phase group does not exist.

  In step S202, inter-channel level correction processing is performed for a plurality of channels belonging to the same phase group. Here, a case where the FL channel and the FR channel are in the same phase group is taken as an example. The processing in step S202 is performed in a state where the frequency characteristics of the equalizer EQ of the channel that is the target of the level correction between channels are adjusted to be flat (all equalizer coefficients are 0). Specifically, first, in the signal processing unit 20, by turning on the switch SW11 and simultaneously turning off the switch SW12, the measurement signal DN (pink noise) is supplied to one channel (for example, FL channel), The measurement signal DN is output from the speaker 6FL. The microphone 8 collects the signal, and the collected sound data DM is supplied to the interchannel level correction unit 12 in the coefficient calculation unit 30 through the amplifier 9 and the A / D converter 10. In the inter-channel level correction unit 12, the level detection unit 12a detects the sound pressure level of the sound collection data DM and sends it to the adjustment amount determination unit 12b. The adjustment amount determination unit 12b generates an adjustment signal SG1 of the interchannel attenuator ATG1 so as to coincide with a predetermined sound pressure level preset in the target level table 12c, and supplies the adjustment signal SG1 to the interchannel attenuator ATG1. Thus, the level of one channel is corrected so as to coincide with a predetermined level. This process is sequentially performed for each channel, and when the level correction is completed for all channels belonging to the same phase group, the process proceeds to step S203.

  Here, the reason why the level correction is performed in step S202 will be described. When level correction is not performed, the levels among a plurality of channels belonging to the same phase group often do not match. For this reason, if level correction is not performed, characteristics of a specific channel having a high level are dominant during frequency characteristic correction performed in the subsequent processing, and equality measurement may not be performed between channels. From the above, the level correction is performed in advance in step S202 in order to accurately perform the frequency characteristic correction performed in the subsequent processing.

  When the levels of the FL channel and the FR channel coincide with each other in the process of step S202, frequency characteristic correction is simultaneously performed on these channels in step S203 and subsequent steps. Specifically, the measurement signal DN is simultaneously output from the channels belonging to the same phase group, that is, the FL channel and the FR channel (step S203), and the collected signal DM is collected by the microphone 8 to obtain the collected sound data DM as a signal processing circuit. 2 is input (step S204). The frequency characteristic correction unit 11 in the signal processing circuit 2 calculates equalizer coefficients SF1 and SF2 for adjusting the characteristics of the equalizers EQ1 and EQ2 based on the sound collection data DM (step S205), and respectively to the equalizers EQ1 and EQ2. Then, the frequency characteristics of the FL channel and the FR channel are corrected (step S206). Thereby, the frequency characteristics of the FL channel and the FR channel are set to desired characteristics. Further, since the FL channel and the FR channel are corrected by the same correction parameter (equalizer coefficient), the phases of both channels coincide with each other. Therefore, the phases between the FL channel and the FR channel can be made to coincide with each other, and both channels can be set to substantially desired frequency characteristics.

  In the above example, the FL channel and the FR channel are in the same phase group, but the number and combination of channels to be selected as the same phase group can be variously set. Thus, when the frequency characteristic correction is completed for one group of in-phase channels, it is checked whether there is another in-phase group (step S207). If there is another in-phase group (step S207: No), the frequency characteristic correction is similarly performed for the next in-phase group (steps S202 to S206).

  On the other hand, when there is no other in-phase group (step S207: Yes), that is, when the frequency characteristic correction is completed for all in-phase channel groups, the remaining channels, that is, in-phase groups are set in step S208 and thereafter. Frequency characteristic correction is performed for independent channels that do not belong. First, it is determined whether or not an independent channel exists (step S208). If it is determined that there is no independent channel (step S208: No), the process returns to the main routine of FIG. On the other hand, if it is determined that an independent channel exists (step S208: Yes), frequency characteristics correction is performed for the independent channel in step S209 and subsequent steps. Specifically, the measurement signal DN is output from one independent channel (step S209) and collected by the microphone 8 (step S210). The frequency characteristic correction unit 11 in the signal processing circuit 2 calculates the equalizer coefficient SF used for the independent channel based on the sound collection data DM (step S211), and supplies the equalizer coefficient SF to the equalizer EQ to obtain the frequency characteristic of the independent channel. Correction is performed (step S212).

  Thus, when the frequency characteristic correction is completed for one independent channel, it is checked whether the frequency characteristic correction is completed for all the independent channels (step S213). If the frequency characteristic correction has not been completed for all the independent channels (step S213: No), the frequency characteristic correction is similarly performed for the next independent channel (steps S209 to S212). When the frequency characteristic correction is completed for all channels (step S213: Yes), the processing returns to the main routine of FIG.

  At the time when the frequency characteristic correction method selection processing in FIG. 9 is completed, the memory 14d in the frequency characteristic correction method selection unit 14 stores data [PxJ] indicating the level of each frequency band for all channels. Therefore, this data [PxJ] may be used in the frequency characteristic correction processing of FIG. In such a case, the analysis for each band in steps S202 to S205 and the analysis for each band in steps S209 to S211 can be omitted, and the processing time can be shortened. However, for the correction of the frequency characteristics of the in-phase group, a process for obtaining an average value [P′zJ] for the data [PxJ] of all channels belonging to the in-phase group is added before the setting of the equalizer coefficient in step S205. Will be.

  Next, the inter-channel level correction process in step S30 of FIG. 8 will be described with reference to FIG. FIG. 12 is a flowchart showing the inter-channel level correction process. The inter-channel level correction process is performed while maintaining the frequency characteristic of the graphic equalizer GEQ set by the previous frequency characteristic correction process adjusted in the frequency characteristic correction process.

  First, in the signal processing unit 20, by turning on the switch SW11 and simultaneously turning off the switch SW12, the measurement signal DN (pink noise) is supplied to one channel (for example, FL channel), and the measurement signal DN is supplied. Is output from the speaker 6FL (step S301). The microphone 8 collects the signal, and the collected sound data DM is supplied to the inter-channel level correction unit 12 in the coefficient calculation unit 30 through the amplifier 9 and the A / D converter 10 (step S302). In the inter-channel level correction unit 12, the level detection unit 12a detects the sound pressure level of the sound collection data DM and sends it to the adjustment amount determination unit 12b. The adjustment amount determination unit 12b generates the adjustment signal SG1 of the interchannel attenuator ATG1 so as to coincide with a predetermined sound pressure level preset in the target level table 12c, and supplies it to the interchannel attenuator ATG1 (step S303). . Thus, the level of one channel is corrected so as to coincide with a predetermined level. This process is performed for each channel in order, and when the level correction is completed for all channels (step S304: Yes), the process returns to the main routine of FIG.

  Next, the delay characteristic correction process in step S40 of FIG. 8 will be described with reference to FIG. FIG. 13 is a flowchart showing the delay characteristic correction process.

  First, for one channel (for example, FL channel), SW11 is turned on and SW12 is turned off, and the measurement signal DN is output from the speaker 6 (step S401). Next, the output measurement signal DN is collected by a microphone, and the collected sound data DM is input to the delay characteristic correction unit 13 in the coefficient calculation unit 30 (step S402). In the delay characteristic correction unit 13, the delay amount calculation unit 13a calculates the delay amount of the channel by calculation and temporarily stores it in the memory 13c (step S403). This process is performed for all other channels. When the processing is completed for all channels (step S404: Yes), the delay amounts of all channels are stored in the memory 13c. Next, based on the stored contents of the memory 13c, the coefficient calculation unit 13b uses the channel having the maximum delay amount among all the channels as a reference, so that the signals of all other channels simultaneously reach the listening position RV. The coefficients of the delay circuits DLY1 to DLY8 of the channel are determined and supplied to each delay circuit DLY (step S405). Then, the delay characteristic correction process is completed. In this way, the frequency characteristic, the inter-channel level, and the delay characteristic are corrected, and the automatic sound field correction is completed.

[Operation and effect of this embodiment]
According to the embodiment described above, the frequency characteristic correction method is selected and set based on the result of analyzing the frequency characteristic of each channel in the user viewing environment. This makes it possible to automatically set a frequency characteristic correction method that is optimal for the user's viewing environment. Specifically, it is possible to automatically set a frequency characteristic correction method that optimizes the user viewing environment in terms of the balance between timbre uniformity and sound image localization.

  In addition, according to the present embodiment, since the optimum frequency characteristic correction method is automatically set, the user can change the frequency characteristic correction method in order to find the optimum frequency characteristic correction method for the viewing environment, and perform automatic sound field correction. There is no need to repeat it over and over. In addition, the user does not need to accurately grasp the viewing environment or properly understand the prepared frequency characteristic correction method.

[Modification]
In the above-described embodiments, three examples of combinations of channels in the same phase group are shown (see FIGS. 7A to 7C). In addition, combinations of channels in the same phase group can be set as appropriate. It is. In the above embodiment, three frequency characteristic correction methods (first to third correction methods) used for such three combinations are shown. However, when other combinations of channels in the same phase group are used. Therefore, an optimal frequency characteristic correction method used for each combination may be set.

  In the above embodiment, both the frequency characteristic between the left and right channels and the frequency characteristic between the front and rear channels are compared (for example, see FIG. 9). Only one of them may be compared. For example, when comparing only the frequency characteristics between the left and right channels, if the frequency characteristics between the left and right channels are different, the frequency correction method is set to the first correction method, and the frequency characteristics between the left and right channels are not different. The frequency correction method may be set to the second correction method. On the other hand, for example, when comparing only the frequency characteristics between the front and rear channels, if the frequency characteristics between the front and rear channels are different, the frequency correction method is set to the first correction method, and the frequency characteristics between the front and rear channels are different. If not, the frequency correction method may be set to the third correction method.

  In the above-described embodiment, the frequency characteristic correction unit 11 includes the bandpass filter 11a and the coefficient table 11b, and the frequency characteristic correction method selection unit 14 includes the bandpass filter 14a and the coefficient table 14b (see FIG. 5 (A) and (B)), only one band pass filter and a coefficient table are provided, and the frequency characteristic correction method selection unit 14 and the frequency characteristic correction unit 11 share the band pass filter and the coefficient table. Also good. Thereby, the size of the DSP program can be reduced.

[Application example]
The present invention can be applied to, for example, an AV receiver and a home theater system.

DESCRIPTION OF SYMBOLS 1 Sound source 2 Signal processing circuit 3 Signal generator for measurement 6 Speaker 8 Microphone 9 Amplifier 10 A / D converter 11 Frequency characteristic correction part 12 Channel level correction part 13 Delay characteristic correction part 14 Frequency characteristic correction system selection part ATG1-ATG8 Attenuator between channels DLY1 to DLY8 Delay circuit EQ1 to EQ8 Equalizer GEQ Graphic equalizer MPU System controller SW11 to SW82, SWN Switch element

Claims (7)

An audio device that enables multi-channel audio output,
A sound collection unit for collecting measurement signals output from the plurality of channels to be frequency-corrected;
A storage unit that stores a frequency amplitude level for each frequency band of the sound collection data collected by the sound collection unit;
The frequency amplitude level stored in the storage unit is compared, and according to the comparison result, a correction group consisting of one or more preset channels is selected, and in the selected correction group unit, An acoustic device comprising: a processing unit that corrects frequency characteristics of a plurality of channels. The processing unit selects the correction group based on the correlation between the frequency amplitude levels between the left and right channels in the plurality of channels , or between the left and right channels and between the front and rear channels, and outputs the correction group unit. The acoustic apparatus according to claim 1, wherein a frequency characteristic is corrected based on sound collection data collected by the sound collection unit.   When the processing unit determines that there is a correlation between the frequency amplitude levels between the left and right channels and that there is no correlation between the frequency amplitude levels between the front and rear channels, the processing unit simultaneously outputs from the left and right channels. The acoustic device according to claim 2, wherein the frequency characteristic is corrected based on sound collection data obtained by collecting the signal for use in the sound collection unit.   When it is determined that there is a correlation between the frequency amplitude levels between the left and right channels and a correlation between the frequency amplitude levels between the front and rear channels, the processing unit outputs the signals simultaneously from all of the plurality of channels. The acoustic device according to claim 2 or 3, wherein the frequency characteristic is corrected based on sound collection data obtained by collecting the measurement signal collected by the sound collection unit.   When it is determined that there is no correlation between the frequency amplitude levels between the left and right channels, the processing unit collects the measurement signals output from each of the plurality of channels by the sound collection unit. The acoustic device according to claim 2, wherein the frequency characteristic is corrected based on the data. A control method executed by an audio device that enables multi-channel audio output,
A sound collecting step for collecting measurement signals output from the plurality of channels to be frequency-corrected;
A storage step of storing a frequency amplitude level for each frequency band of the sound collection data collected by the sound collection step;
The frequency amplitude levels stored in the storage step are compared, and according to the comparison result, a correction group consisting of one or more preset channels is selected, and in the selected correction group unit, And a processing step of correcting frequency characteristics of a plurality of channels. A program that enables audio output of a plurality of channels and that is executed by an audio device having a computer,
The computer,
Sound collecting means for collecting measurement signals output from the plurality of channels to be frequency-corrected;
Storage means for storing a frequency amplitude level for each frequency band of the sound collection data collected by the sound collection means;
The frequency amplitude level stored by the storage means is compared, and a correction group consisting of one or more preset channels is selected according to the comparison result, and in the selected correction group unit, A program that functions as a processing unit that corrects frequency characteristics of a plurality of channels.

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