JP2006005902A - Amplifier and amplitude frequency characteristics adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce noise generation, deterioration in sound quality, and uncomfortable feeling about acoustic feeling caused from deviations in phase between channels, deterioration in the SN ratio, and distortions in an output signal by excessive corrections in the frequency characteristics. <P>SOLUTION: An amplifier comprises a signal processing unit for correcting the frequency characteristics of an output signal outputted from a speaker to a predetermined target frequency characteristics, based on a collected signal after collecting a measuring signal which is outputted from the speaker and collected by a microphone. The signal processing unit is designed to compare the measured frequency characteristics acquired from the collected signal with the target frequency characteristics; to acquire the frequency characteristics correcting value for reducing the difference between the measured frequency characteristics and the targeted frequency characteristics; to acquire a calculation correcting value for determining the correction degree of the frequency characteristics by the frequency characteristics correcting value; and to perform correction of the frequency characteristics, using the frequency characteristics correcting value and the calculation correcting value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention amplifies an audio signal, outputs it, and adjusts the amplitude frequency characteristic of the audio signal output from the speaker, and adjusts the amplitude frequency characteristic of the audio signal output from the speaker. The present invention relates to a method for adjusting amplitude frequency characteristics.

  In recent years, multi-channel audio playback systems such as home theater systems have become widespread. In this multi-channel audio playback system, a playback device plays back an audio signal recorded on a recording medium, converts the audio signal played back by the playback device into a multi-channel audio signal, amplifies it, and outputs it to a plurality of speakers. An amplifying device is provided.

  In order to reproduce an audio signal with high quality sound quality in the amplification device, the phase of the audio signal between the channels, the roll-off (cut-off) frequency of the output signal of each channel, and the sound of the entire output signal of each channel It is necessary to set various parameters related to acoustic characteristics such as pressure level, distance between the listening point and the speaker, and frequency characteristics of sound pressure level of each channel output signal to appropriate values. Conventionally, listeners have manually set the values of these parameters, but in recent years, devices having an automatic sound field correction function for automatically setting the values of these parameters have appeared. Hereinafter, the amplitude frequency characteristic of the audio signal is simply referred to as “frequency characteristic”.

  The automatic sound field correction function outputs a measurement signal from each speaker, picks up the sound output from each speaker with a microphone installed at the listening point, and collects the frequency characteristics of the collected audio signal and the entire audio signal. Compare the sound pressure level, delay time of the audio signal of each channel, etc. with the preset frequency characteristics, sound pressure level, delay time, etc., and remove the difference so that the frequency characteristics of the audio signal of each channel The sound pressure level of the entire audio signal and the delay time of the audio signal of each channel are corrected. As a result, an optimal audio signal can be restored at the listening point. An apparatus having such an automatic sound field correction function is disclosed in Patent Document 1 and Patent Document 2.

  In the multi-channel audio playback device disclosed in Patent Document 1 and the automatic sound field correction system disclosed in Patent Document 2, a measurement signal output from each speaker is collected and collected based on the measurement result. Obtain the frequency characteristics of the audio signal that was sounded, automatically obtain the equalizer coefficient by calculation so that the frequency characteristic matches the preset target frequency characteristic, and form an equalizer with the calculated coefficient set The sound field is automatically corrected by outputting an audio signal via the equalizer.

  In addition, when restoring the optimal audio signal at the listening point by the automatic sound field correction function, even when listening around the listening point by calculation based on each characteristic collected at one listening point Japanese Patent Application Laid-Open No. 2003-228867 discloses a technique for correcting the delay and level of an audio signal output from each speaker so that the same reproduction characteristics as when listening at a listening point can be obtained.

JP 2000-354300 A JP2001-224092 JP 2000-59898

  The correction of the frequency characteristic of the audio signal in the multi-channel audio reproduction device disclosed in Patent Document 1 and the automatic sound field correction system disclosed in Patent Document 2 is performed by setting a target frequency in which the frequency characteristic obtained by measurement is set in advance. Correction is performed using a coefficient obtained by calculation so as to match the characteristic.

  In the measurement of the acoustic characteristics by the automatic sound field correction function, the sound output from the speaker is input to the microphone directly or reflected on the wall of the room, so the frequency characteristics of the audio signal collected by the microphone are There are many peaks (dips where the signal level is high) and dips (concaves where the signal level is low) or peaks and dips where the level is very high. These peaks or dips can be automatically corrected for frequency characteristics by calculation of automatic sound field correction, but by correcting the frequency characteristics obtained by measurement to match the preset target frequency characteristics. In some cases, a phase shift between channels of an audio signal may occur, an SN (Signal Noise) ratio may decrease, or distortion may occur in an output signal.

  Specifically, when correcting a frequency characteristic having a peak and a dip whose level changes suddenly, that is, a frequency characteristic having a peak and a dip in a narrow frequency band that cannot be perceived by humans, the target frequency characteristic is calculated in terms of calculation. Correct peaks and dips exactly to match. However, the equalizer used to correct the frequency characteristics with a narrow frequency band between the peak and the dip has a frequency characteristic having a sharp curve (a signal level suddenly becomes low or high) at the peak and dip portions. Since the phase of this part changes extremely, this phase change causes a shift in the phase relationship between the channels.

  When correcting a frequency characteristic having a peak and dip having a very large level, the peak and dip are accurately corrected so as to coincide with the target frequency characteristic. In the calculation for this correction, headroom must be secured. Headroom refers to the “margin” of how much level of signal can be handled with respect to the operating level of each audio device. The level at which the audio device is distorted and the level of the sound actually output from the audio device The difference is shown. For example, a digital recorder has a headroom of 20 dB, and a mixing console head amplifier has a headroom of about 30 dB.

  In the calculation for correcting the frequency characteristic, the S / N ratio of the audio signal is reduced by ensuring the headroom. In particular, in order to correct a dip having a large level, if the signal level of the frequency of the dip is increased, the headroom increases and the SN ratio of the audio signal decreases.

  Among speakers, there is a speaker having frequency characteristics in which a dip exists in a part of the audible band. Since such a dip is a frequency characteristic of the speaker itself, a signal higher than the signal level of the dip portion is not output. When correction is made so that the signal level of the dip portion is increased by correcting the frequency characteristics, a signal waveform having a frequency at which the signal level has been increased is clipped, and distortion occurs in the output signal from the speaker.

  As described above, the frequency characteristic obtained by the measurement may have a peak and dip whose level changes abruptly, a peak and dip having a very large level, or a dip in some bands. When the frequency characteristics are automatically corrected so that the frequency characteristics obtained by measuring these peaks or dips by the automatic sound field correction calculation match the target frequency characteristics, the phase shift between the channels of the audio signal The sound field deviates from the normal position due to the sound, the sound is uncomfortable, the noise component of the audio signal is increased due to a decrease in the S / N ratio, and the sound quality of the audio signal is deteriorated due to the distortion of the output signal. May deteriorate.

  Further, in the listening position correction device disclosed in Patent Document 3, based on each characteristic collected at one listening point, the listening area around the listening point is divided into nine areas, respectively. Assuming that the center of each area is the listening position, the optimum reproduction condition at each listening position is obtained by calculation, and the delay and level of the audio signal output from the speaker are corrected. However, if the listening area around the listening point is too wide or too narrow than the actual listening position, the optimum playback condition cannot be obtained at the actual listening position.

  The present invention, when correcting the amplitude frequency characteristics of an audio signal, causes a sense of incongruity, an increase in noise components, and a decrease in sound quality caused by correcting the frequency characteristics obtained by measurement so as to match the target frequency characteristics. It is an object of the present invention to provide an amplifying apparatus and an amplitude frequency characteristic adjusting method that can reduce noise. It is another object of the present invention to provide an amplifying apparatus and an amplitude frequency characteristic adjusting method capable of obtaining optimum reproduction conditions even when the listening position is moved.

  The present invention measures an amplitude frequency characteristic of a signal output from a speaker connected to the amplification apparatus in an amplification apparatus capable of amplifying and outputting an audio signal and adjusting the amplitude frequency characteristic of the audio signal. A measurement signal generator for generating a measurement signal for output, an output unit for outputting the measurement signal generated by the measurement signal generator, and a microphone for collecting the measurement signal output from a speaker A sound collection signal input unit to which the collected sound collection signal is input, and a signal processing unit that corrects the amplitude frequency characteristic of the audio signal output from the speaker based on the sound collection signal to a predetermined target frequency characteristic And the signal processing unit compares the measured frequency characteristic obtained from the collected sound signal with the target frequency characteristic, and compares the measured frequency characteristic with the target frequency. A frequency characteristic correction value having the smallest difference from the characteristic is obtained, an arithmetic correction value for determining the degree of correction of the frequency characteristic in the frequency characteristic correction value is obtained, and an audio is obtained using the frequency characteristic correction value and the arithmetic correction value. It is characterized by correcting the amplitude frequency characteristic of the signal.

  The invention of the present application relates to an amplifying apparatus capable of amplifying and outputting an audio signal and adjusting the amplitude frequency characteristic of the audio signal, wherein the amplitude frequency characteristic of a signal output from a speaker connected to the amplifying apparatus is A measurement signal generator that generates a measurement signal for measurement, an output unit that outputs the measurement signal generated by the measurement signal generator, and a microphone that collects the measurement signal output from a speaker And a signal processing unit that corrects an amplitude frequency characteristic of an audio signal output from a speaker based on the collected sound signal to a predetermined target frequency characteristic. The signal processing unit includes a peak or a peak in the measurement frequency characteristic based on the measurement frequency characteristic and the target frequency characteristic. A frequency characteristic correction value composed of a filter coefficient corresponding to the peak or dip and an arithmetic correction value composed of a correction value multiplied by the filter coefficient corresponding to the peak or dip, and the frequency characteristic correction value And the calculation correction value are used to correct the amplitude frequency characteristic of the audio signal.

  The invention of the present application is the amplification device described above, wherein the signal processing unit uses the calculation correction value as a level difference rate between the peak or dip characteristic and the characteristic based on the filter coefficient and the audio based on the characteristic based on the filter coefficient. A correction value corresponding to the filter coefficient is determined based on a signal distortion rate, and an operation correction value is obtained based on the correction value.

  The invention of the present application relates to an amplitude frequency characteristic adjustment method capable of adjusting an amplitude frequency characteristic of an audio signal, a step of generating a measurement signal for measuring the amplitude frequency characteristic of a signal output from the speaker, and a speaker. Obtaining a measurement frequency characteristic from a collected sound signal picked up by a microphone that picks up the measurement signal output from, comparing the measured frequency characteristic with the target frequency characteristic, and the measured frequency characteristic Determining a frequency characteristic correction value having the smallest difference between the frequency characteristic correction value and the target frequency characteristic; determining a calculation correction value for determining a degree of correction of the frequency characteristic in the frequency characteristic correction value; and Correcting the amplitude frequency characteristics of the audio signal using the calculated correction value. The features.

  The invention of the present application relates to an amplifying apparatus capable of amplifying and outputting an audio signal and adjusting the amplitude frequency characteristic of the audio signal, wherein the amplitude frequency characteristic of a signal output from a speaker connected to the amplifying apparatus is A measurement signal generator that generates a measurement signal for measurement, an output unit that outputs the measurement signal generated by the measurement signal generator, and a microphone that collects the measurement signal output from a speaker And a signal processing unit that corrects an amplitude frequency characteristic of an audio signal output from a speaker based on the collected sound signal to a predetermined target frequency characteristic. Each of the measurement frequency characteristics obtained from the respective sound pickup signals picked up by the microphones at a plurality of measurement positions. A constant frequency characteristic and the target frequency characteristic are compared, a frequency characteristic correction value having the smallest difference between the measurement frequency characteristic and the target frequency characteristic is obtained for each measurement frequency characteristic, and the frequency characteristic correction value is obtained for each obtained frequency characteristic correction value. An arithmetic correction value for determining the degree of correction of the frequency characteristic is obtained, an average value of the obtained plural frequency characteristic correction values and an average value of the plural arithmetic correction values are obtained, and the average value of the frequency characteristic correction value and the arithmetic operation are calculated. The amplitude frequency characteristic of the audio signal is corrected using the average value of the correction values.

  The invention of the present application relates to an amplitude frequency characteristic adjustment method capable of adjusting an amplitude frequency characteristic of an audio signal, a step of generating a measurement signal for measuring the amplitude frequency characteristic of a signal output from the speaker, and a speaker. Obtaining a plurality of measurement frequency characteristics from the collected sound signals picked up at a plurality of measurement positions by a microphone that picks up the measurement signals output from the measurement frequency characteristics, Comparing the target frequency characteristics, obtaining a frequency characteristic correction value having the smallest difference between each measurement frequency characteristic and the target frequency characteristic for the plurality of measurement frequency characteristics, and calculating the plurality of frequency characteristic correction values A step for obtaining a calculation correction value that determines the degree of correction of the frequency characteristic in each frequency characteristic correction value. An audio signal using the step of calculating an average value of the obtained plurality of frequency characteristic correction values and an average value of the plurality of calculation correction values, and the average value of the frequency characteristic correction values and the average value of the calculation correction values And a step of correcting the amplitude frequency characteristic.

  The invention of the present application relates to an amplifying apparatus capable of amplifying and outputting an audio signal and adjusting the amplitude frequency characteristic of the audio signal, wherein the amplitude frequency characteristic of a signal output from a speaker connected to the amplifying apparatus is A measurement signal generator that generates a measurement signal for measurement, an output unit that outputs the measurement signal generated by the measurement signal generator, and a microphone that collects the measurement signal output from a speaker A sound pickup signal input unit to which a sound pickup signal picked up by the sound is input, and an arrival time of the audio signal from the speaker to the microphone based on the sound pickup signal and an amplitude frequency of the audio signal output from the speaker A signal processing unit that corrects the characteristic to a predetermined target frequency characteristic, and the signal processing unit is The measured frequency characteristics and the target frequency characteristics are compared for each measured frequency characteristic obtained from the collected sound signals collected by the lophone, and the difference between the measured frequency characteristic and the target frequency characteristic is the smallest for each measured frequency characteristic. Obtain a frequency characteristic correction value, obtain an arithmetic correction value for determining the degree of frequency characteristic correction in the frequency characteristic correction value for each frequency characteristic correction value obtained, and calculate an average value and a plurality of calculations of the obtained multiple frequency characteristic correction values. An average value of the correction values is obtained, and the amplitude frequency characteristics of the audio signal are corrected using the average value of the frequency characteristic correction values and the average value of the calculation correction values, and microphones at a plurality of measurement positions from each speaker. Discriminating the placement of each speaker based on the arrival time of the audio signal from the speaker to the microphone obtained from the collected sound signal , And switches the channel of the audio signals adapted to the speaker by the output unit when the audio signal of the channel to be output to the position and the speaker of the speaker do not match.

  According to the present invention, when correcting an amplitude frequency characteristic of an audio signal in an amplification device or an amplitude frequency characteristic adjustment method capable of correcting a frequency characteristic, the frequency characteristic obtained by measurement matches the target frequency characteristic. As a result, it is possible to reduce the sense of incongruity, the increase of noise, and the deterioration of sound quality caused by the correction. Even when the listening position is moved, the optimum reproduction condition can be obtained.

FIG. 1 is a diagram showing the configuration of the first embodiment of the amplifying apparatus of the present invention.
In FIG. 1, the amplifying apparatus includes a signal processing unit 1, an output unit 2, a measurement signal generation unit 3, a collected sound signal input unit 4, an operation unit 5, and a control unit 6.

  The signal processing unit 1 is, for example, a digital signal processor (DSP), and performs signal processing such as decoding and delay on an audio signal input from an external device. The decoding process includes, for example, a process of converting a 2-channel audio signal into a 6-channel audio signal, a process of expanding a compressed audio signal, and the like. The delay process is a process of adding a delay time to each decoded audio signal of each channel in order to give the listener a sense of presence when outputting audio signals from a plurality of speakers.

  The signal processing unit 1 is controlled by the control unit 6 to be described later, based on the sound collection signal input from the sound collection signal input unit 4, in the environment where the listener listens to the audio signal in a space where a plurality of speakers are arranged. The values of various parameters of the acoustic characteristics such as the frequency characteristics, delay time, and sound pressure level of the audio signal of each channel are automatically corrected so that an optimal acoustic effect can be obtained at the listening point. The operation for making this setting is called automatic sound field correction processing.

  When correcting the frequency characteristics obtained by measurement to the target frequency characteristics in the automatic sound field correction processing, the signal processing unit 1 compares these frequency characteristics to obtain a difference, and obtains the frequency characteristics obtained by the measurement. A frequency characteristic correction value for matching with the target frequency characteristic is obtained. Then, based on the frequency characteristic correction value, a calculation correction value (to be described later) for determining the degree of correction by calculation is obtained, and the frequency characteristic is corrected using the frequency characteristic correction value and the calculation correction value.

  Here, the signal processing unit 1 corrects the frequency characteristic of the audio signal by calculation using the frequency characteristic, the target frequency characteristic, the frequency characteristic correction value, and the calculation correction value obtained by measurement. This correction is performed by forming a parametric equalizer on the calculation program in the signal processing unit 1 and changing the frequency and signal level values constituting the parametric equalizer by calculation. A parametric equalizer sets the frequency of an arbitrary peak or dip as the center frequency from among the peaks or dips in the frequency characteristics of one band of a graphic equalizer (divides the audible band and adjusts the level for each band). And change the frequency characteristics.

  The signal processing unit 1 includes a memory 1a, and stores parameter values set by the automatic sound field correction processing in the memory 1a. The audio signal is stored in the memory 1a until the listener uses the operation unit 5 to change the parameter value so that the frequency characteristic desired by the listener is obtained, or until the parameter value is changed by automatic sound field correction processing. Based on the stored value, signal processing is performed and output.

  The output unit 2 includes a digital / analog conversion unit (not shown) and an amplification unit (not shown). The digital audio signal of a plurality of channels input from the signal processing unit 1 is converted into an analog signal. The front left channel speaker (hereinafter referred to as “FL speaker”) 7a, the front right channel speaker (hereinafter referred to as “FR speaker”) 7b, and the center channel speaker connected to the output unit 2 are amplified. (Hereinafter referred to as “C speaker”) 7c, surround left channel speaker (hereinafter referred to as “SL speaker”) 7d, surround right channel speaker (hereinafter referred to as “SR speaker”) 7e, subwoofer channel speaker (hereinafter referred to as “SL speaker”). , "SW speaker") 7f it Is the output.

  The output unit 2 is controlled by the control unit 6 so that the listener can change the frequency characteristic so that the frequency characteristic desired by the listener is obtained during the automatic sound field correction process or after the automatic sound field correction process. When instructed using the operation unit 5, the measurement signal generated by the measurement signal generation unit 3 is output to the speakers 7a to 7f of the respective channels.

  The measurement signal generator 3 generates measurement signals for measuring the values of various parameters when the frequency characteristic is automatically corrected in the automatic sound field correction process under the control of the control unit 6. The measurement signal is a signal having a frequency band wider than the audible band, and is, for example, an impulse, a time stretched pulse, white noise, or the like.

  The sound collection signal input unit 4 receives the input of the sound collection signal input from the microphone 8 connected to the sound collection signal input unit 4 in the automatic sound field correction process under the control of the control unit 6, and receives the signal processing unit 1. Output to.

  The operation unit 5 includes operation buttons for switching on / off the automatic sound field measurement process, operation buttons for inputting or changing various parameter settings of acoustic characteristics, and the like. When the listener presses the operation button, the operation unit 5 outputs an instruction signal corresponding to the pressed operation button to the control unit 6.

  The control unit 6 comprehensively controls the entire amplification device. The control unit 6 controls the signal processing unit 1 to perform decoding processing, delay processing, and the like on the audio signal input from the external device, and output the audio signal from the output unit 2.

  When an instruction signal indicating that the automatic sound field correction processing is on is input from the operation unit 5, the control unit 6 causes the measurement signal generation unit 3 to generate a measurement signal, and the measurement signal is transmitted via the signal processing unit 1. Then, control is performed to output from the output unit 2 to each speaker. The measurement signal output from the speaker is collected by the microphone 8 and input to the sound collection signal input unit 4. Then, the control unit 6 causes the signal processing unit 1 to obtain values of various parameters of acoustic characteristics based on the sound collection signal input from the sound collection signal input unit 4, and stores the obtained values in the memory 1a. Then, the value is set as the value of various parameters of the acoustic characteristics, and control for correcting the acoustic characteristics is performed.

An automatic sound field correction process in the amplifying apparatus of the first embodiment will be described.
As shown in FIG. 1, in a multi-channel playback system such as a home theater system having six speakers 7a to 7f, the acoustic characteristics of the room, the frequency characteristics of the speakers used, the phase characteristics of each channel, and the audio signal from the speakers. The speaker 7a of each channel at the listening point depends on the transmission characteristics of the transmission path until the listener listens to the audio signal, the type and number of speakers used, the installation position of the speakers, the arrangement of the listening point and each speaker, etc. Since the phase characteristics, roll-off frequency, sound pressure level of the entire audio signal, distance from the listening point to each speaker, and the amplitude frequency characteristics of the audio signal change, the listener receives the audio signal of the same sound source. Even before listening Phase characteristic of a roll-off frequency, sound pressure level, distance, tone due to the difference in frequency characteristics, sound field, sound different and realism.

  An audio signal reproduced by an external device and input to the amplification device is premised on an appropriate environment for listening to the audio signal. For example, the sound pressure level of the output signal of each channel is equal, the distance between the speakers 7a to 7f, the frequency characteristics of each speaker are appropriate, and listening is performed in an environment where an appropriate type of speaker is used as the speaker configuration. Therefore, in order to reproduce the audio signal output from the amplification device with an optimal sound, an appropriate environment must be prepared.

  In order to reproduce the audio signal output from the amplifying device with the optimum sound, in the automatic sound field correction process, the acoustic characteristics of the room, the characteristics of the speakers used, the transmission characteristics of the transmission path, etc. are measured and the audio based on the measurement results Correct the signal. The automatic sound field correction process includes a measurement process and a correction process, and the measurement process is first executed.

  The measurement process is a process of measuring the current acoustic characteristic at the listening point. Speakers 7a to 7f that output audio signals are arranged as shown in FIG. 1, and a measurement microphone 8 is arranged at a listening point.

  In the measurement process, the control unit 6 causes the measurement signal generation unit 3 to generate a measurement signal and causes the output unit 2 to sequentially output the measurement signal from the output unit 2 to the speakers 7a to 7f via the signal processing unit 1. The measurement signals output from the speakers 7 a to 7 f are collected by the microphone 8. The collected sound signal output from the microphone 8 is input to the collected sound signal input unit 4 and input to the signal processing unit 1. The signal processing unit 1 obtains an impulse response by calculation based on the measurement signal generated by the measurement signal generation unit 3 and the collected sound signal input to the collected sound signal input unit 4. Signals output from the amplifying device are output from the speakers 7a to 7f, and transfer characteristics until the signals are picked up by the microphone 8 are impulse responses obtained here.

  Based on this impulse response, the sound pressure level, peak level, etc. of the output signal of each channel are obtained by calculation, and FFT (Fast Fourier Transform) analysis is performed, so that the speaker configuration (presence / absence of speaker, speaker size), between speakers The phase relationship, the distance between the speakers, the distance from the listening point to each speaker, the sound pressure level and frequency characteristics of the output signal from each speaker can be obtained.

Then, the process proceeds to correction processing.
In the correction process, various parameters are corrected based on the measurement result obtained in the measurement process.

  The signal processing unit 1 sets the number of speakers based on the presence or absence of speakers, and corrects the delay time between channels based on the distance between speakers or the distance from the listening point to each speaker, based on the measurement results obtained in the measurement process. Correction of difference in sound pressure level of output signal between channels based on sound pressure level of output signal of each speaker, correction of frequency characteristic of output signal of each channel based on frequency characteristic of output signal of each speaker, etc. The coefficient for this is obtained by calculation.

  The coefficient obtained by the calculation is stored in the memory 1a. When an audio signal input from an external device is output, the coefficient stored in the memory 1a is used to correct the frequency characteristic and the phase of the audio signal. Correction, sound pressure level correction, output time delay and other signal processing are performed and output.

  The amplifying device uses the values obtained by the calculation as various parameters of the signal processing unit 1 (speaker size, number of speakers, distance between speakers, distance from the listening point to each speaker, delay time of each channel, sound of each channel) Pressure level, frequency characteristics of each channel, etc.) and display section of amplifying device (not shown) so that the listener can check the setting as a result of automatic sound field correction Or it displays on the monitor (not shown) connected to the amplifier, and an automatic sound field correction process is completed.

Next, frequency characteristic correction in the automatic sound field correction process will be described.
The signal processing unit 1 includes information indicating a plurality of target frequency characteristics (values indicating the target frequency characteristics) in advance, and these target frequency characteristics are obtained by the listener before the measurement process of the automatic sound field correction process. It is possible to select using the operation unit 5. In the correction process of the automatic sound field correction process, a frequency characteristic correction value for matching the frequency characteristic obtained from the measurement result with the target frequency characteristic is obtained, and an operation correction value is obtained based on the frequency characteristic correction value. The frequency characteristic is corrected by calculation using the value. Then, the signal processing unit 1 outputs an audio signal having a corrected frequency characteristic.

FIG. 2 is a diagram for explaining the correction process of the automatic sound field correction process in the amplifying apparatus of the first embodiment.
FIG. 3 is a diagram for explaining the calculation related to the filter coefficient Q in the amplifying apparatus of the first embodiment.
FIG. 4 is a diagram for explaining the calculation related to the calculation correction value R in the amplifying apparatus of the first embodiment.
In the automatic sound field correction process, the control unit 5 causes the measurement signal generation unit 3 to generate a measurement signal and measures the frequency characteristics of each speaker. As a result of the measurement, it is assumed that the frequency characteristic A shown in FIG.

  The frequency characteristic A in FIG. 2A is a frequency characteristic obtained by smoothing the frequency characteristic obtained by measurement by the signal processing unit 1 for each octave band such as 1/3 octave or 1/6 octave. This is because frequency characteristics obtained by measurement are frequency characteristics including loudspeaker frequency characteristics, room acoustic characteristics, loudspeaker placement, reflection by an object in the room, etc. Become.

  In order to correct all the peaks and dips of such frequency characteristics, it is difficult to assign a parametric equalizer to each peak and dip because the calculation process becomes complicated and the calculation time is long. For this reason, the frequency characteristic obtained by the measurement is smoothed, and the frequency characteristic is corrected for the smoothed frequency characteristic A.

  FIG. 2B is an example of the target frequency characteristic T. In the automatic sound field correction process, the frequency characteristic is corrected so that the frequency characteristic A shown in FIG. 2A approaches the target frequency characteristic T shown in FIG.

  The control unit 5 controls the signal processing unit 1 and first detects a signal level at a reference frequency f (n) to be described later in the frequency characteristic A shown in FIG. 2A, and FIG. The signal level at the reference frequency f (n) is detected in the target frequency characteristic T shown in FIG.

  The reference frequency f (n) is a frequency in a frequency band (for example, 1 kHz to 2 kHz) that is most sensitive to changes in signal level in the sense of hearing included in the human voice band. This is because the frequency characteristic correction by the conventional automatic sound field correction processing accurately matches the frequency characteristic obtained by the measurement with the target frequency characteristic, so that the sense of incongruity due to the phase shift, noise increase, and sound quality decrease. Arise.

  In the automatic sound field correction processing of the present embodiment, in order to reduce the sense of incongruity due to the phase shift, the increase of noise components, and the deterioration of sound quality, the frequency characteristics obtained by measurement are set as target frequency characteristics in a certain frequency band. By making a precise matching, the degree of correction in the peak and dip parts is reduced in other frequency bands, and measurement is performed to reduce the sense of incongruity due to phase shift, increase in noise components, and decrease in sound quality. Correction is performed so that the obtained frequency characteristic approaches the target frequency characteristic.

  In the correction of the frequency characteristic of the first embodiment, the frequency characteristic obtained by measurement and the target frequency characteristic do not exactly match at a peak or dip portion where the difference between the frequency characteristic obtained by measurement and the target frequency characteristic is large. Part occurs. If the frequency characteristic obtained by this measurement and the target frequency characteristic do not exactly match the frequency band frequency that is most sensitive to changes in the signal level, the frequency characteristic in that part is not much corrected for hearing. As perceived by the listener.

  For this reason, in the correction of the frequency characteristic in the present embodiment, the reference frequency for correcting the frequency characteristic is set to a frequency in the frequency band that is most sensitive to a change in the signal level in human hearing, so that the frequency is measured. Since the obtained frequency characteristic matches the target frequency characteristic, the listener does not perceive that the frequency characteristic is not so much corrected.

  The signal level x (n) of the reference frequency f (n) in the frequency characteristic A shown in FIG. 2A is the signal level x ′ () of the reference frequency f (n) in the target frequency characteristic T shown in FIG. n) Increase or attenuate the overall signal level of the frequency characteristic A to match n). In this embodiment, it is attenuated. As a result, the frequency characteristic A shown in FIG. 2A becomes the frequency characteristic A ′ shown in FIG.

  Next, in the frequency characteristic A ′ shown in FIG. 2C, the signal level of the target frequency characteristic T and the signal level of the frequency characteristic A ′ are compared for each frequency, and a signal higher than the signal level of the target frequency characteristic T is obtained. A level portion (peak portion) or a portion (dip portion) having a signal level lower than the signal level of the target frequency characteristic T is detected.

  For each detected peak or dip, the absolute value of the signal level difference g with respect to the signal level of the target frequency characteristic T is detected. In FIG. 2C, the absolute value of the signal level difference g1 of the frequency fc1 is the largest, the absolute value of the signal level difference g2 of the frequency fc2 is next largest, and the absolute value of the signal level difference g3 of the frequency fc3 is the value of these. It is assumed that the smallest is detected.

  When the dip portion of the signal level difference g1 having the maximum absolute value of the signal level difference g is detected, the frequency fc1 of the signal level difference g1 is set as the center frequency of the parametric equalizer, and the signal level difference g1 is set in the parametric equalizer. Set as the frequency characteristic correction level.

  Then, as shown in FIG. 2D, for the dip part of the characteristic P1 having the signal level difference g1 at the frequency fc1, the filter coefficient Q and the correction value R for bringing the dip part of the characteristic P1 close to the target frequency characteristic T are obtained. Ask. The filter coefficient Q is ideally a value that can obtain a characteristic that is symmetrical to the dip portion of the characteristic P1. The correction value R is a value that determines the degree of correction of the frequency characteristic in the dip portion of the characteristic P1 by a parametric equalizer using the filter coefficient Q.

  The filter coefficient Q is obtained by the signal processing unit 1 having a plurality of (for example, 10) filter candidate coefficients q (n) as a table in advance, and the signal level difference g1 and frequency fc1 of the dip part of the characteristic P1. A filter is configured based on each filter candidate coefficient q (n), and a parametric equalizer using the filter is formed. The frequency characteristic of the parametric equalizer and the characteristic P1 are compared for each frequency in the frequency band of the dip portion of the characteristic P1 to calculate a difference, and the filter candidate coefficient q (n having the smallest level difference is calculated. ) Is the filter coefficient Q1 of the dip portion of the characteristic P1.

  Specifically, as shown in FIG. 3 (a), a parametric equalizer is formed on each of the plurality of filter candidate coefficients qa to qj prepared in advance for the dip portion of the characteristic P1, by calculation. For each filter candidate coefficient qa to qj, the frequency characteristic by the parametric equalizer and the characteristic P1 are compared for each frequency in the frequency band of the dip portion of the characteristic P1, and the sum (difference) of the level difference of each frequency is compared. ) Is calculated. As a result, for each of the filter candidate coefficients qa to qj, the difference in signal level between the frequency characteristic of the parametric equalizer using the filter candidate coefficients qa to qj and the characteristic P1 is obtained.

  The difference in signal level between the frequency characteristic of the parametric equalizer using the filter candidate coefficients qa to qj and the characteristic P1 is as shown in FIG. 3B. The frequency characteristic and the characteristic P1 obtained by the parametric equalizer are as shown in FIG. The filter candidate coefficient qg having the smallest difference is defined as the filter coefficient Qg.

  Next, for the obtained filter coefficient Qg, a correction value R that determines the degree of correction of frequency characteristics by a parametric equalizer using the filter coefficient Qg is obtained. The degree of correction of the frequency characteristic in the dip portion varies depending on the peak level of the characteristic based on the filter coefficient Qg. For example, the lower the characteristic peak level based on the filter coefficient Qg, the lower the correction degree, and the higher the characteristic peak level based on the filter coefficient Qg, the higher the correction degree. By multiplying the filter coefficient Qg by the correction value R, the degree of correction is determined.

  As the correction value R, one correction value R is selected from a plurality of correction candidate values r (n) obtained based on the signal level difference g1 of the dip portion of the characteristic P1. This selection method will be described later.

  Each correction candidate value r (n) is obtained by equally dividing the signal level difference g1 of the dip portion of the characteristic P1 by a predetermined number (for example, 10), and each equally divided level becomes a peak level. The characteristic based on the filter coefficient Qg is shown. For example, the characteristics of the filter coefficient Qg based on the correction candidate values ra to rj are as shown in FIG. 4A, and are obtained by multiplying the filter coefficient Qg by the calculation correction candidate values ra to rj.

  Possible values of the correction candidate value r (n) are, for example, 0.1 to 1. When the correction value R selected from the plurality of correction candidate values r (n) is 0.1, the frequency characteristic is corrected by 10% by the parametric equalizer using the filter coefficient Qg (correction 10%: FIG. 4 ( In a), when the correction candidate value ra) and the correction value R selected from the plurality of correction candidate values r (n) are 1, the frequency characteristic is corrected 100% by a parametric equalizer using the filter coefficient Qg. (Correction 100%: correction candidate value rj in FIG. 4A). When the correction value R is 0, the frequency characteristic is not corrected by the parametric equalizer using the filter coefficient Qg (correction 0%), so the value 0 is excluded from the correction candidate value r (n).

  For example, when the center frequency fc (n) of the dip portion is 500 Hz and the signal level (peak level) of the frequency 500 Hz is 10 dB lower than the signal level of the target frequency characteristic, in the frequency characteristic by the parametric equalizer using the filter coefficient Qg A correction equalizer that amplifies a signal level of a frequency of 500 Hz is configured. In this case, the correction candidate value r (n) is r = 0.1 (correction 10%) for correction of +1 dB, r = 0.2 (correction 20%) for correction of +2 dB,... +10 dB correction Then, r = 1 (correction 100%). From these values, an appropriate correction candidate value r (n) is selected as a correction value R to be used for correcting the frequency characteristic of the dip portion of the characteristic P1 by an operation described later.

  A parametric equalizer for the characteristic (FIG. 4A) of the filter coefficient Qg based on each correction candidate value ra to rj is formed, and the level difference between the characteristic P1 and the characteristic of the filter coefficient Qg based on each correction candidate value ra to rj The distortion rate of the audio signal in the characteristics of the filter coefficient Qg based on the rate and each correction candidate value ra to rj is obtained.

First, the level difference rate between the characteristic P1 and the characteristic of the filter coefficient Qg based on each correction candidate value ra to rj will be described.
The level difference ratio is calculated by calculating the sum Xa of the absolute values of the signal levels of the respective frequencies of the characteristic P1, and calculating the sum Xb of the absolute values of the signal levels of the respective frequencies of the characteristics of the filter coefficient Qg based on the respective correction candidate values ra to rj. The level difference rate is calculated by dividing the sum Xb by the sum Xa.

  The sum Xa uses the signal level of the target frequency characteristic T as a reference value, obtains the signal level of the characteristic P1 with respect to the reference value at each frequency within the frequency band of the dip portion of the characteristic P1, and calculates the absolute value of the obtained signal level. Calculated as the sum Xb. Further, the sum Xb is the frequency of the dip portion of the characteristic P1 with respect to the characteristic of the filter coefficient Qg based on the respective correction candidate values ra to rj, with the signal level of the part where the signal level is flat in the characteristic of the filter coefficient Qg as a reference value. At each frequency in the frequency band corresponding to the band, the signal level of the characteristic of the filter coefficient Qg based on each correction candidate value ra to rj with respect to the reference value is obtained, and the absolute value of the obtained signal level is calculated as the sum Xa.

  The level difference rate is, for example, a characteristic diagram as shown in FIG. In the case of the correction candidate value ra, since the peak level of the filter coefficient Qg characteristic is low as shown in FIG. 4A, the sum Xb in the characteristic of the filter coefficient Qg based on the correction candidate value ra is small. As a result, in the case of the correction candidate value ra, the level difference rate between the total sum Xb and the total sum Xa of the characteristics P1 becomes high as shown in FIG. That is, the characteristic of the filter coefficient Qg based on the correction candidate value ra indicates that the degree of correction of the frequency characteristic is low.

  In the case of the correction candidate value rj, as shown in FIG. 4A, since the peak level of the filter coefficient Qg characteristic is high, the total Xb in the characteristic of the filter coefficient Qg based on the correction candidate value rj becomes large. As a result, in the case of the correction candidate value rj, the level difference rate between the total sum Xb and the total sum Xa of the characteristic P1 becomes low as shown in FIG. That is, the characteristic of the filter coefficient Qg based on the correction candidate value ra indicates that the degree of correction of the frequency characteristic is high.

  Then, as shown in FIG. 4B, the level difference rate in the characteristic of the filter coefficient Qg based on the characteristic P1 and each of the correction candidate values ra to rj is almost as it goes from the correction candidate value ra to the correction candidate value rj. The characteristic is linearly lowered.

  As described above, the level difference rate between the characteristic P1 and the characteristic of the filter coefficient Qg based on the correction candidate values ra to rj is as shown in FIG. 4B. The level difference rate decreases as the characteristic deviates from the symmetrical characteristic of the characteristic P1 and the characteristic of the filter coefficient Qg based on the correction candidate values ra to rj becomes closer to the symmetrical characteristic of the characteristic P1.

Next, the distortion rate of the audio signal in the characteristics of the filter coefficient Qg based on the correction candidate values ra to rj will be described.
The distortion rate has a peak level of each correction candidate value ra to rj for each of the correction candidate values ra to rj, and a sine wave of the center frequency (fc1 shown in FIG. 2 (d)) of the dip portion in the characteristic P1 is loudspeaker. The sound is picked up by a microphone, the geometric mean value of the sum of the effective values of the harmonic components of the picked up signal is obtained, and the ratio between the geometric mean value and the effective value of the fundamental wave of the output signal is obtained. Ask.

  In the frequency characteristic having the dip part of the characteristic P1, when the frequency characteristic is corrected so that the level of the audio signal output from the speaker is higher than the level of the dip part, the signal waveform of the increased frequency is clipped. Distortion (harmonic component) occurs in the output signal from the speaker. For each of the correction candidate values ra to rj, the distortion rate is calculated using a signal output from the speaker and a signal collected by the microphone.

  Specifically, a sine wave having a peak level of the correction candidate value ra is output from the speaker, the sound is collected by a microphone, and a geometric mean value of the sum of the effective values of the harmonic components of the collected sound signal is obtained. The ratio between the geometric mean value and the effective value of the fundamental wave of the output signal is obtained. Next, a sine wave having a peak level of the correction candidate value rb is output from the speaker, the sound is picked up by a microphone, and a synergistic average value of the sum of the effective values of the harmonic components of the sound pickup signal is obtained. The ratio between the average value and the effective value of the fundamental wave of the output signal is obtained. This operation is repeated to obtain the distortion rate in each of the correction candidate values ra to rj.

  Then, the distortion rate of the audio signal becomes a characteristic diagram as shown in FIG. Note that in FIG. 4C, the distortion rate on the vertical axis is expressed as a logarithm so that a value of 1% or less can be visually recognized in describing the distortion rate threshold value described later. In FIG. 4C, the distortion rate is low in the case of the correction candidate values ra to rd, the distortion rate gradually increases from the case of the correction candidate value re, and the distortion rate is the highest in the case of the correction candidate value rj.

  From the distortion rate of the audio signal in the characteristics of the filter coefficient Qg based on the correction candidate values ra to rj thus determined and the level difference rate described above, the distortion is lower than a predetermined distortion rate (distortion rate threshold). The correction candidate value r (n) that is the rate and has the lowest level difference rate is obtained. The predetermined distortion rate is, for example, 0.01%, which is a distortion rate of a general audio device.

  For example, in the case of the characteristic diagram shown in FIG. 4C, the correction candidate value rg is a value whose distortion rate is lower than the distortion rate threshold (0.01%) and whose level difference rate is low. That is, the correction candidate value rg has a high degree of correction of the frequency characteristic of the dip portion of the characteristic P1 and has a low distortion rate of the audio signal, and the correction candidate value rg is set as the correction value R1.

  In the first embodiment, the level difference rate between the characteristic P1 and the characteristic of the filter coefficient Qg based on the correction candidate values ra to rj and the distortion rate of the audio signal in the characteristic of the filter coefficient Qg based on each correction candidate value ra to rj. First, the level difference rate and the distortion rate are obtained for the correction candidate value ra, and then the correction candidate values ra to rj are sequentially changed so that the level difference rate and the distortion rate are obtained for the correction candidate value rb. The level difference rate and the distortion rate are obtained for, but when the correction candidate value r (n) with the distortion rate exceeding the distortion rate threshold value is obtained, the calculation is stopped, and the correction value R is determined based on the previous calculation result. It may be. As a result, the calculation time required to obtain the correction value R can be shortened.

  As a result of these calculations, for the dip portion of the characteristic P1 having the center frequency fc1 with the signal level difference g1, the filter coefficient Qg and the correction value R1 used for the parametric equalizer for correcting the dip portion are determined. When a parametric equalizer is formed based on these values, a characteristic S1 shown in FIG. 2E is obtained as a characteristic for correcting the dip portion. When the dip portion of the characteristic P1 of the center frequency fc1 is corrected with the signal level difference g1 by the parametric equalizer, the result is as shown in FIG.

  After the filter coefficient Qg and the correction value R1 for correcting the dip portion of the characteristic P1 are determined, the signal level difference in which the absolute value of the signal level difference g is the maximum in the frequency characteristic A ′ shown in FIG. For the dip portion of g2, the filter coefficient Q and the correction value R2 that are characteristics S2 for correcting the dip portion of the signal level difference g2 are determined by the same calculation as described above. By repeating this process, the filter coefficient Q and the correction value R for each peak portion and dip portion of the frequency characteristic A ′ are obtained.

  A value indicating the characteristic composed of all the filter coefficients Q obtained for each peak and dip of the frequency characteristic A ′ in this way is the frequency characteristic correction value. Further, a value composed of all the correction values R obtained for each peak and dip of the frequency characteristic A ′ is an operation correction value by which the frequency characteristic correction value is multiplied. A parametric equalizer having the frequency characteristic C shown in FIG. 2G is formed using the frequency characteristic correction value and the calculation correction value, and the frequency characteristic of the audio signal is corrected using the parametric equalizer.

  As described above, when correcting the peak or dip in the frequency characteristic correction, the frequency characteristic correction value and the calculation correction value are used to reduce the difference between the acquired frequency characteristic and the target frequency characteristic. By performing the correction, the frequency characteristic is corrected so that the frequency characteristic obtained by the measurement matches the target frequency characteristic, thereby suppressing the phase shift of the audio signal, the decrease in the S / N ratio, and the occurrence of distortion of the output signal. In addition, it is possible to reduce the sense of incongruity, noise generation and sound quality degradation.

  In the first embodiment described above, the frequency characteristic is corrected in the automatic sound field correction process. However, after the automatic sound field correction process, the frequency characteristic is corrected manually by the listener. May be.

  In the first embodiment, the correction value R is set to a level difference rate between the characteristic P1 and the characteristic of the filter coefficient Qg based on the correction candidate values ra to rj, and the characteristic of the filter coefficient Qg based on the correction candidate values ra to rj. However, the listener listens to the audio signal output from the speaker, and uses the operation unit 5 to determine that the audio signal is not distorted for audibility. The corrected value may be determined as the correction value R.

  Further, in the first embodiment, the amplification device capable of amplifying and outputting the audio signal and adjusting the frequency characteristic of the audio signal output from the speaker has been described. However, the frequency characteristic of the audio signal input from the outside is described. The present invention can also be applied to an equalizer capable of adjusting.

  In the first embodiment described above, the measurement point for measuring the output signal from the speaker in the automatic sound field correction processing is set as one listening point. However, the present invention is not limited to this, and the automatic sound is calculated based on the measurement results at a plurality of locations. A field correction process may be performed. In the automatic sound field correction process described above, the point at which the measurement was performed is the optimal listening point, but when the listener listens at a position slightly deviated from the measurement position, or when there are multiple listeners, You will hear outside the optimal listening point. Next, as a second embodiment, a description will be given of a process in which measurement is performed at a plurality of locations in the automatic sound field correction process of the first embodiment described above, and sound field correction is performed based on the measurement result.

  The amplifying apparatus in the second embodiment has the same configuration as that shown in FIG. The second embodiment differs from the amplifying apparatus of the first embodiment in the processing of the control unit and the signal processing unit.

  In the second embodiment, first, frequency characteristics are measured at a listening point (a position that is substantially the center of a plurality of speakers) when there is only one listener, and a frequency characteristic correction value and a calculation correction value are calculated. A correction frequency characteristic C shown in FIG. 2G is obtained using the frequency characteristic correction value and the calculation correction value.

  In the first embodiment, since only one point is measured for one listener, only one frequency characteristic C for correction can be obtained. Since this characteristic is a characteristic when the listener is limited to the place where the measurement microphone is installed, strictly speaking, the correction is not reflected in a place where the listener moves even a little from the place. In addition, when the parametric equalizer is formed based on the correction frequency characteristic C obtained at the measurement position and the frequency characteristic is corrected, the correction effect of the frequency characteristic is merely reduced at a place away from the measurement position. On the contrary, the sound quality may be deteriorated audibly by correction.

  In the second embodiment, the number of measurement points is increased to several points near the listening point in addition to the listening point. In the present embodiment, in addition to the listening point, the number of measurement points is increased by four, and measurement is performed at a total of five points. As a result, it is possible to perform acoustic correction in consideration of a relatively wide range in the vicinity of the listening point by grasping the characteristics of the acoustic characteristics in the vicinity of the listening point and performing automatic sound field correction based on the characteristics.

  The frequency characteristics between the plurality of speakers and the microphones obtained from one measurement point are different even at a position slightly moved from the measurement point. However, when a plurality of frequency characteristics measured at a plurality of locations near the measurement point are statistically analyzed, there are portions similar to the frequency characteristics. This similar portion is a characteristic that does not depend on the measurement position, that is, a frequency characteristic of the speaker itself or an acoustic characteristic at a measurement point that deviates from the listening point.

  In the second embodiment, in consideration of reduction in calculation time and downsizing of the amplification device, five frequency characteristics for correction obtained by measurement and calculation are averaged for each frequency as the simplest statistical analysis technique. This averaging process makes the frequency characteristic unique to each measurement point inconspicuous. Further, it is possible to extract only the characteristics inherent to a plurality of speakers and the overall spatial characteristics of the room used for listening, by averaging the frequency characteristics common to each measurement point.

FIG. 5 is a diagram for explaining the measurement of frequency characteristics in the automatic sound field correction processing of the amplifying apparatus according to the second embodiment of the present invention.
FIG. 6 is a diagram illustrating a process for obtaining a correction frequency characteristic in the automatic sound field correction process of the amplifying apparatus according to the second embodiment.
In FIG. 5A, a monitor is installed in the listening room, the front is the front, two front speakers are installed on the front left and right of the listening point, and two rear speakers are installed on the left and right rear of the listening point. Assume that it is installed.

  The frequency characteristic measurement points are a listening point (listening point) P1 when there is only one listener, a point P2 on the left side of the listening point P1, a point P3 on the right side of the listening point P1, a point P4 in front of the listening point P1, Let it be point P5 behind listening point P1.

  For measurement of the frequency characteristics at each point, a microphone device as shown in FIG. 5B is used. The microphone device collects a signal output from each speaker by each microphone. By using the microphone device, it is not necessary to move the microphone to the measurement position, and the frequency characteristic can be measured, so that the measurement time can be shortened.

  The signal processing unit 1 of the amplifying apparatus performs measurement and calculation in order from the point P1. First, the frequency characteristic of each speaker at the point P1 is measured by the microphone installed at the point P1, and the correction frequency characteristic Cp1 is obtained by the correction process described in the first embodiment based on the measurement result.

  Next, the frequency characteristic of each speaker at the point P2 is measured by the microphone installed at the point P2, and the correction frequency characteristic Cp2 is obtained by the correction process described in the first embodiment based on the measurement result. Similarly, the frequency characteristics of the speakers at P3, P4, and P5 are measured at the points with the microphones installed at the points P3, P4, and P5, and the correction frequency characteristics Cp3, Cp4, and Cp5 are obtained based on the measurement results. . FIG. 6 shows the obtained correction frequency characteristics Cp1 to Cp5.

  After obtaining the correction frequency characteristics Cp1 to Cp5, the signal processing unit 1 of the amplification device then obtains an average value for each frequency with respect to the correction frequency characteristics obtained at the five measurement points shown in FIG. . A parametric equalizer is formed based on the correction frequency characteristic Cav obtained as a result of averaging, and the frequency characteristic is corrected.

  As a result, it is possible to correct the frequency characteristics to the optimum in the range surrounded by the points P2 to P5 with the point P1 as the center. Therefore, even when the listener moves the listening point a little, the listener can listen to the audio signal with the optimum frequency characteristics.

  In the second embodiment, the measurement apparatus shown in FIG. 5B is used. However, after the measurement of the frequency characteristic and the calculation of the correction frequency characteristic at each point using one microphone, the following is performed. The listener may move the microphone to the measurement point.

  An amplification device (AV amplifier) used in a multi-channel audio reproduction system such as a home theater system must connect a plurality of devices and speakers. Therefore, a large number of terminals for cable connection of the amplifying device are provided. The listener associates the terminals with the speakers and wires them with cables, but the speaker is often installed in the wrong place or the connection between the terminals and the speaker is often wrong, and the connection mistake is not noticed at the time of connection. Audio signals may be listened to by incorrectly connected speakers. If it does so, the optimal surround effect will not be acquired and a listener will have to rewire a cable and will be troublesome.

  In the amplifying apparatus of the second embodiment, frequency characteristics are measured at five locations around the listening point when there is only one listener, and therefore the connection and installation of a plurality of speakers are appropriate using the measurement results. Whether it can be determined automatically. As a result, it is possible to eliminate the connection error between the speaker and the terminal and the installation error of the speaker, and to easily construct an environment in which the user listens to the audio signal in an appropriate state.

FIG. 7 is a diagram for explaining the arrangement of measurement points and speakers in the second embodiment.
In the measurement of the frequency characteristic of the output signal from each speaker in the second embodiment, the distance to each speaker at each measurement point is calculated. As shown in FIG. 7, speakers SP1 to SP8 are arranged.

  When measured at the point P1, the distance between the point P1 and each of the speakers SP1 to SP8 can be measured by impulse response measurement. However, it is not possible to determine in which direction the speakers SP1 to SP8 are located in the left / right front / rear direction with respect to the point P1.

  When measurement is performed at point P2 following point P1, whether the speakers SP1 to SP8 are located on the left or right side in the X-axis direction with respect to the point P1 (listening point) is determined based on the difference in arrival time of the measurement signals from the respective speakers. Can be determined.

  For example, in the measurement result at the point P1, it is assumed that the distance Ls1p1 between the point P1 and the speaker SP1 and the distance Ls3p1 between the point P1 and the speaker SP3 are the same at the measurement point P1 (Ls1p1 = Ls3p1). In the measurement result of the point P2, the distance Ls1p2 between the point P2 and the speaker SP1 and the distance Ls3p2 between the point P2 and the speaker SP3 are shorter for the speaker SP1 than for the speaker LP3 (Ls1p2 <Ls3p2). That is, it can be determined that the speaker SP1 is located on the left with respect to the point P1, and the speaker SP3 is located on the right with respect to the point P1.

  Similarly, by measuring at point P3, the arrangement relationship of the speakers obtained from the measurement results at points P1 and P2 becomes clearer. For example, it is assumed that the speaker SP2 is installed in front of the point P1. In the previous measurement, the position of the speaker SP2 is determined only on the right side in the X-axis direction with respect to the speaker SP1. However, from the measurement result at the point P3, it can be determined that the speaker SP2 is located at least between the speakers SP1 and SP3. Further, when the distance between the point P2 and the point P3 is equal to the point P1, the position of each speaker is clarified by the trigonometric method from the measurement result of each of the two measurement points, and the speaker SP2 is in the Y axis It can be determined that it exists in the front or back of the direction.

  Further, from the measurement result at the point P4, it becomes clear whether the speakers SP1 to SP8 are positioned in the Y-axis direction before or after the point P1. Similarly, the arrangement of each speaker becomes clearer from the measurement result at the point P5.

  Based on the distance from each speaker to the microphone obtained at these measurement points P1 to P5, it is possible to grasp in which direction the speakers SP1 to SP8 are located with respect to the point P1 in the front, rear, left and right directions. Based on this measurement result, if the speaker is connected incorrectly or the speaker is not installed at an appropriate location, a warning may be displayed to the listener using a display device built in the monitor or the device body. it can. As a result, it is possible to reduce time and effort required for the listener to reproduce the audio signal once and notice the wiring mistake and then reroute the cable.

  In addition, if it is determined that the cable wiring is not correct based on the measurement results, the audio signal channel that is automatically output from the output unit inside the amplifier is switched, so that even if there is a cable wiring mistake, Users can watch movies and music without having to rewire.

The figure which shows the structure of one Example of the amplifier of this invention. The figure explaining the correction process of the automatic sound field correction process in the amplification apparatus of a present Example. The figure for demonstrating the calculation regarding the filter coefficient Q in the amplification apparatus of a present Example. The figure explaining the calculation regarding the correction value R in the amplification apparatus of a present Example. The figure explaining the measurement point in the automatic sound field correction process of the amplifier of 2nd Example of this invention. The figure explaining the process which calculates | requires the frequency characteristic for a correction | amendment in the automatic sound field correction process of the amplifier of 2nd Example. The figure explaining arrangement | positioning of a measurement point and each speaker in 2nd Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Signal processing part, 1a ... Memory, 2 ... Output part, 3 ... Measurement signal generation part, 4 ... Sound collection input part, 5 ... Operation part, ... Control unit, 7 ... speaker, 7a ... front left speaker (FL), 7b ... front right speaker (FR), 7c ... center speaker (C), 7d ... surround left speaker ( SL), 7e ... surround light speaker (SR), 7f ... subwoofer speaker (SW), 8 ... microphone.

Claims (7)

  Amplifying apparatus capable of amplifying and outputting an audio signal and adjusting the amplitude frequency characteristic of the audio signal, and measuring the amplitude frequency characteristic of a signal output from a speaker connected to the amplifying apparatus A measurement signal generator that generates a measurement signal, an output unit that outputs the measurement signal generated by the measurement signal generator, and a microphone that collects the measurement signal output from a speaker. A sound collection signal input unit to which a sound collection signal is input, and a signal processing unit that corrects an amplitude frequency characteristic of an audio signal output from a speaker based on the sound collection signal to a predetermined target frequency characteristic, The signal processing unit compares the measured frequency characteristic obtained from the collected sound signal with the target frequency characteristic, and compares the measured frequency characteristic with the target frequency characteristic. A frequency characteristic correction value having the smallest minute is obtained, an arithmetic correction value for determining the degree of correction of the frequency characteristic in the frequency characteristic correction value is obtained, and the amplitude of the audio signal is determined using the frequency characteristic correction value and the arithmetic correction value. An amplifying apparatus for correcting frequency characteristics.   Amplifying apparatus capable of amplifying and outputting an audio signal and adjusting the amplitude frequency characteristic of the audio signal, and measuring the amplitude frequency characteristic of a signal output from a speaker connected to the amplifying apparatus A measurement signal generator that generates a measurement signal, an output unit that outputs the measurement signal generated by the measurement signal generator, and a microphone that collects the measurement signal output from a speaker. A sound collection signal input unit to which a sound collection signal is input, and a signal processing unit that corrects an amplitude frequency characteristic of an audio signal output from a speaker based on the sound collection signal to a predetermined target frequency characteristic, The signal processing unit detects a peak or dip in the measurement frequency characteristic based on the measurement frequency characteristic and the target frequency characteristic, A frequency characteristic correction value composed of a filter coefficient corresponding to the peak or dip and an arithmetic correction value composed of a correction value multiplied by the filter coefficient corresponding to the peak or dip are obtained, and the frequency characteristic correction value and the arithmetic correction value are obtained. And an amplitude device for correcting the amplitude frequency characteristics of the audio signal.   3. The amplification device according to claim 2, wherein the signal processing unit uses the calculation correction value as a level difference rate between the peak or dip characteristic and the characteristic based on the filter coefficient, and an audio signal in the characteristic based on the filter coefficient. An amplifying apparatus, wherein a correction value corresponding to the filter coefficient is determined based on a distortion rate, and an arithmetic correction value is obtained based on the correction value.   In an amplitude frequency characteristic adjustment method capable of adjusting an amplitude frequency characteristic of an audio signal, a step of generating a measurement signal for measuring the amplitude frequency characteristic of a signal output from a speaker; and the output from the speaker Obtaining a measurement frequency characteristic from a collected sound signal picked up by a microphone that picks up the measurement signal; comparing the measurement frequency characteristic with the target frequency characteristic; and the measurement frequency characteristic and the target frequency characteristic. Obtaining a frequency characteristic correction value having the smallest difference between the frequency characteristic correction value, a step of obtaining a calculation correction value for determining a degree of correction of the frequency characteristic in the frequency characteristic correction value, and the frequency characteristic correction value and the calculation correction value. And correcting the amplitude frequency characteristics of the audio signal. Width frequency characteristic adjusting method.   Amplifying apparatus capable of amplifying and outputting an audio signal and adjusting the amplitude frequency characteristic of the audio signal, and measuring the amplitude frequency characteristic of a signal output from a speaker connected to the amplifying apparatus A measurement signal generator that generates a measurement signal, an output unit that outputs the measurement signal generated by the measurement signal generator, and a microphone that collects the measurement signal output from a speaker. A sound collection signal input unit to which a sound collection signal is input, and a signal processing unit that corrects an amplitude frequency characteristic of an audio signal output from a speaker based on the sound collection signal to a predetermined target frequency characteristic, The signal processing unit is configured to measure each measurement frequency characteristic for each measurement frequency characteristic obtained from each collected sound signal picked up by a microphone at a plurality of measurement positions. The target frequency characteristics are compared, a frequency characteristic correction value having the smallest difference between the measurement frequency characteristic and the target frequency characteristic is obtained for each measurement frequency characteristic, and the frequency characteristic in the frequency characteristic correction value is determined for each obtained frequency characteristic correction value. An arithmetic correction value for determining the degree of correction is obtained, an average value of the obtained plural frequency characteristic correction values and an average value of the plural arithmetic correction values are obtained, and an average value of the frequency characteristic correction value and an average of the arithmetic correction value are obtained. An amplifying apparatus that corrects an amplitude frequency characteristic of an audio signal using a value.   In an amplitude frequency characteristic adjustment method capable of adjusting an amplitude frequency characteristic of an audio signal, a step of generating a measurement signal for measuring the amplitude frequency characteristic of a signal output from a speaker; and the output from the speaker Obtaining a plurality of measurement frequency characteristics from the collected sound signals picked up at a plurality of measurement positions by a microphone that picks up the measurement signal; and measuring each of the plurality of measurement frequency characteristics and the target frequency characteristic. A step of comparing, a step of obtaining a frequency characteristic correction value having the smallest difference between each measurement frequency characteristic and the target frequency characteristic for the plurality of measurement frequency characteristics, and each frequency characteristic correction value for the obtained plurality of frequency characteristic correction values Obtaining a calculation correction value for determining the degree of correction of the frequency characteristic in Calculating an average value of a plurality of frequency characteristic correction values and an average value of a plurality of calculation correction values, and using the average value of the frequency characteristic correction values and the average value of the calculation correction values, And a step of performing correction.   Amplifying apparatus capable of amplifying and outputting an audio signal and adjusting the amplitude frequency characteristic of the audio signal, and measuring the amplitude frequency characteristic of a signal output from a speaker connected to the amplifying apparatus A measurement signal generator that generates a measurement signal, an output unit that outputs the measurement signal generated by the measurement signal generator, and a microphone that collects the measurement signal output from a speaker. A sound pickup signal input unit to which a sound pickup signal is input and an arrival time of an audio signal from a speaker to a microphone based on the sound pickup signal are measured, and an amplitude frequency characteristic of the audio signal output from the speaker is determined in advance. And a signal processing unit that corrects the target frequency characteristics, and the signal processing unit includes microphones at a plurality of measurement positions. For each measured frequency characteristic obtained from each collected sound signal, the measured frequency characteristic is compared with the target frequency characteristic, and for each measured frequency characteristic, the difference between the measured frequency characteristic and the target frequency characteristic is the smallest frequency characteristic correction value For each of the obtained frequency characteristic correction values, an arithmetic correction value that determines the degree of correction of the frequency characteristic in the frequency characteristic correction value is obtained, and the average value of the obtained multiple frequency characteristic correction values and the average of the multiple arithmetic correction values are obtained. And correcting the amplitude frequency characteristics of the audio signal using the average value of the frequency characteristic correction values and the average value of the calculation correction values, and collecting the sound collected by the microphones at a plurality of measurement positions from each speaker. The placement of each speaker is determined based on the arrival time of the audio signal from the speaker to the microphone obtained from the sound signal. Amplifier and wherein the switching to the audio signal of the channel adapted to the speaker by the output unit when the audio signal of the channel to be output to the location and the speaker do not match.

Images