JP2006171347A - Audio signal processing method and audio reproducing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reproduction characteristics of a signal of small sound volume from a speaker according to characteristics of an actually installed speaker. <P>SOLUTION: When correction processing for outputting an input audio signal from a speaker system with specified input/output characteristics is performed, a reference audio signal is input to the speaker system and output, based upon the reference audio signal is picked up by a microphone; and the audio signal obtained by the microphone is compared with the reference audio signal to analyze a decrement in sensitivity for each level and the correction processing for compensating the decrement in sensitivity is carried out for a signal component of a level with the decrease in analyzed sensitivity of the audio signal to be supplied to the speaker system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an audio signal processing method for correcting characteristics when an audio signal is reproduced from a speaker device, and an audio playback system for correcting the characteristics, and particularly uses a speaker device for high-fidelity reproduction capable of high-quality reproduction. The present invention relates to a technique suitable for application to a case.

  Conventionally, speakers having various configurations have been put to practical use as speaker devices for high-fidelity reproduction capable of high-quality reproduction. For example, there is a three-way speaker device in which a reproduction band of an audio signal is divided into three bands, a low band, a middle band, and a high band, and an individual speaker unit is prepared for each band. This three-way speaker device uses a speaker unit with good reproduction characteristics in each band as a speaker unit for each band, and can faithfully reproduce the input audio signal from low to high frequencies. In general, the reproduction characteristics are improved as compared with a so-called full-range speaker unit that outputs audio in all bands with a single speaker unit.

  Further, in addition to the configuration for improving the sound quality of the reproduction sound of the speaker device as in the three-way configuration or the two-way configuration, the characteristics of the audio signal itself supplied to the speaker device are also an amplifier that is an audio signal processing device. Corrections are made on the device side, and as a result, the characteristics of audio output from the speaker device are improved. For example, an audio amplifier device that performs processing such as amplification of an audio signal that drives a speaker device may perform correction called loudness control. This loudness control corrects the low and high frequencies that are heard when the volume is low, mainly by performing a correction process that increases the output level of the low and high frequencies compared to the mid range. Is.

Patent Document 1 describes an example of a reproduction configuration when performing loudness correction.
JP 2002-171589 A

  However, the loudness-controlled playback sound simply boosts the signal in a specific frequency band almost uniformly regardless of the level, so it cannot be said that the playback sound is faithful to the input audio signal in a strict sense. Development of a reproduction system that can reproduce signals faithfully has been desired. In other words, conventional loudness-controlled playback sounds are played back with an increase in sounds that are difficult to hear at low volumes, making it easier to hear low and high frequencies compared to playback sounds that are not loudness-controlled. However, it is possible to enhance signal components that do not need to be enhanced because signals in a specific frequency band are uniformly enhanced at both low and large levels. In some cases, this results in an unnatural playback sound.

  Here, the problem of the reproduced sound in the conventional speaker device will be described. As an example when the reproduced sound does not faithfully reproduce the input audio signal, there is a problem of a small amplitude signal. That is, for example, as shown in FIG. 9A, it is assumed that an input audio signal S1 having a waveform in which a relatively large amplitude waveform and a relatively small amplitude waveform are continuous is input to the speaker. At this time, the waveform of the output audio signal S2 from the speaker is substantially the same as that of the input signal S1 for a waveform having a relatively large amplitude, but the amplitude of the waveform of a relatively small amplitude is larger than that of the input signal S1. It tends to be smaller. This is because a speaker unit having a general diaphragm that can output a relatively loud sound has poor reproduction characteristics of a small volume signal with small amplitude, and linearity of input / output characteristics of a small volume signal ( This is because linearity is not ensured.

  Similarly, for example, as shown in FIG. 9B, the input audio signal S3 having a relatively large amplitude waveform and the input audio signal S4 having a relatively small amplitude waveform overlap each other in time, An audio signal S5 obtained by synthesizing both signals S3 and S4 is output, and an output audio signal S6 having a waveform whose level is lower than the waveform of the synthesized signal S5 is output from the speaker. For example, such an output state may occur when sounds of various musical instruments are reproduced simultaneously as audio to be reproduced from a speaker, such as symphony.

  Further, for example, as shown in FIG. 9 (c), when an impulse signal in which the amplitude of a specific single frequency signal gradually decreases is an input audio signal S7, the waveform of the output audio signal S8 from the speaker However, the follow-up property becomes worse as the level becomes lower.

  In any of the examples in FIG. 9, as an output from the speaker, the output level of a small volume signal having a small amplitude becomes smaller than the input signal level, and the linearity of the small signal cannot be maintained. When the state shown in FIG. 9 is subjected to frequency analysis, for example, the state shown in FIG. 10 is obtained. The example of FIG. 10 is an example in which the sensitivity of the fundamental wave f1 and harmonics f2 and f3 that are harmonics of the fundamental wave is analyzed. The fundamental wave f1 having a high level is output as it is, but the harmonics f2 and f3 having a level lower than that of the fundamental wave have the output sensitivity indicated by the solid line that is lower than the original level indicated by the broken line. ing.

  FIG. 11 is a diagram showing output characteristics from a low range to a high range at a plurality of signal levels. FIG. 11A is an ideal characteristic, and FIG. 11B is an actual speaker output. It is the figure which showed the characteristic. As shown in FIG. 11A, in an ideal state, it is assumed that the four levels L1, L2, L3, and L4 have a flat characteristic from a low range to a high range at almost equal intervals. At this time, as the actual output characteristics of the speaker shown in FIG. 11 (b), the output characteristics having the high output levels L1, L2, and L3 have almost the same output characteristics as the ideal characteristics, but the lowest level. Regarding the characteristics of L4, the sensitivity α decreases from the originally required level by any sensitivity in the frequency band.

  FIG. 12 is an input / output characteristic diagram showing such a decrease in sensitivity as a characteristic of a specific frequency. As shown in FIG. 12, the characteristic must be a broken line characteristic x in which the output level increases linearly with an increase in the input signal level to the speaker. The level changes almost linearly, but below a specific level, the vibration of the diaphragm with respect to the input is poor and the output sensitivity to the input is a curve characteristic y.

  Specifically, for example, assuming that the maximum level of listening by a general speaker is 70 to 100 spl (sound pressure level), a signal that is −30 dB to −60 dB lower than the maximum level is correct with respect to the maximum level − This means that the sound volume is not reduced (not proportional) from 30 dB to -60 dB. If it is assumed that the output of the amplifier device is reduced by 50 spl from 100 spl, the sound volume should be around 50 spl, but in reality, for example, only 40 spl lower than 10 spl can be obtained. It will not be possible. In other words, the inventor's analysis revealed that the linearity was not accurately obtained, which was one of the major causes that a satisfactory sound quality could not be obtained.

  By the way, the curve state of the curve of the characteristic y shown in FIG. 12 described above is an example, and actually, the specific curve state of the characteristic y varies depending on the characteristic of each speaker device. End up. That is, the input / output characteristics of a speaker device are determined by conditions such as the size and weight of the vibration system of the speaker unit included in the speaker device, and may vary depending on the installation environment of the speaker device. It was difficult to decide.

  The present invention has been made in view of such a point, and an object thereof is to improve the reproduction characteristics of a relatively low volume signal from a speaker.

  The present invention inputs a reference audio signal to a speaker device when performing correction processing for outputting the input audio signal from the speaker device having predetermined input / output characteristics, and outputs the reference audio signal as a microphone. Compare the audio signal picked up by the microphone and the reference audio signal, analyze the amount of decrease in sensitivity for each level, and the signal component of the audio signal supplied to the speaker device that reduces the analyzed sensitivity level On the other hand, correction processing for compensating for the decrease in sensitivity is performed.

  As a result, the audio signal output from the speaker device becomes an audio signal having a substantially linear input / output characteristic in which the lack of sensitivity is corrected in accordance with the characteristic of the speaker device. A relatively low level signal whose level is insufficient can be satisfactorily output at the original level.

  According to the present invention, since the audio actually output from the speaker device is analyzed, the sensitivity to be corrected can be optimally set according to the speaker device, and corrected according to the characteristics of the connected speaker device. Thus, an audio signal having substantially linear input / output characteristics can be output, and in particular, a relatively small level signal that originally has an insufficient output level is favorably output at the original level.

  In this case, reproduction characteristics can be improved in all frequency bands by performing correction processing that compensates for the decrease in output sensitivity almost uniformly for each level within almost all frequency bands output by the speaker device. Thus, reproduction with high fidelity to the input audio signal is possible, which is completely different from the conventional enhancement of only a specific band such as loudness control.

  Further, by providing a storage means for storing the amount of decrease in sensitivity for each level analyzed by the analysis means, for example, when installing a playback system, the output audio of the speaker device is analyzed and stored only once using a microphone. Thereafter, the optimum correction using the stored data can be performed.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a system configuration example according to the present embodiment. In this example, an audio reproduction system to which a speaker device is connected is shown as an example installed in a vehicle such as an automobile, and FIG. 1 is a diagram showing an example of the overall system configuration. In this example, the audio signal source 10 is connected to the amplifier device 20, and the audio signal source 10 reproduces an audio signal recorded (stored) on a medium such as a CD (disc) or a memory, and reproduces it. The output audio signal is supplied to the amplifier device 20, and the amplifier device 20 performs processing to convert the audio signal to drive the speaker device. An audio signal received and input by a tuner (not shown) may be used. Details of a specific processing state in the amplifier device 20 will be described later.

  Here, as shown in FIG. 1, a plurality of speaker devices 31, 32, 33, and 34 are arranged at predetermined positions in the vehicle. Specifically, for example, the speaker devices 31 and 32 are arranged on the left and right in the front of the vehicle, and the speaker devices 33 and 34 are arranged on the left and right in the rear.

  The audio signal output from the audio signal source 10 is at least a two-channel signal of a left channel audio signal and a right channel audio signal. For example, the left channel audio signal output from the amplifier device 20 is a left channel audio signal. The audio signals for the right channel are supplied to and output from the speaker devices 32 and 34 for the right channel.

  The configuration of each of the speaker devices 31, 32, 33, and 34 will be described. Each of the speaker devices 31 to 34 includes one speaker unit as a speaker unit serving as a sound output unit that outputs audio. Each speaker unit is a so-called full-range speaker unit that has characteristics that are output from a low frequency range to a high frequency range with a frequency characteristic that is almost flat within the audible frequency range as viewed from the output frequency band. A relatively large speaker unit having a relatively large diaphragm and capable of outputting a loud signal is provided. As for the speaker unit constituting the speaker device of this example, since the diaphragm is relatively large, the linearity (linearity) of the input / output characteristics of large signals above a predetermined level is almost maintained, and the input / output characteristics below the predetermined level. Therefore, the output signal level is inferior to the input signal level. That is, the speaker unit having the characteristic y described with reference to FIG. 12 in the background art column is used. A speaker unit having such characteristics is general as a speaker.

  In this example, in an audio reproduction system to which speaker devices 31 to 34 using speaker units having such characteristics are connected, a signal is transmitted on the amplifier device 20 side that processes an audio signal supplied to the speaker devices 31 to 34. The characteristic correction is performed.

  FIG. 2 is a diagram showing the configuration of the amplifier device 20 of this example. As shown in FIG. 2, an audio signal obtained at the audio signal input terminal 21 of the amplifier device is supplied to an analog / digital converter 22 to be converted into a digital audio signal, and the converted digital audio signal is converted into a DSP (digital signal). A signal processor 23 is supplied. In this example, the DSP 23 is used as a means for correcting audio signal characteristics. The correction state in the DSP 23 is set by control by the control unit 26. A memory 27 for storing data necessary for control is connected to the control unit 26, and data about the correction state in the DSP 23 is also stored. Further, a reference audio signal necessary for performing an analysis described later is also stored in the memory 27, and the reference audio signal can be supplied to the speaker side and output instead of the input audio signal.

  As correction processing in the DSP 23, for example, signal components in all frequency bands are divided into signal components of a predetermined level or higher and signal components of a predetermined level or lower for digital signal processing. Does not perform correction processing. For signal components below a predetermined level, correction processing is performed so that the output level is lower than the input level, and the increase rate increases as the level decreases. Here, in this example, the correction processing state can be variably set by the control of the control unit 26. In the correction processing in this example, the optimum correction state is automatically set based on the actually measured reproduction state. However, the correction state can be adjusted by a user key operation or the like. Also good. Details of the correction state will be described later.

  Then, a signal component of a predetermined level or higher that has not been subjected to correction processing and a signal component of lower than the predetermined level that have been subjected to correction processing are combined, and the combined signal is supplied to the digital / analog converter 24 to generate an analog audio signal. Convert.

  The converted analog audio signal is supplied to the amplifier 25 and amplified for driving the speaker, and the amplified audio signal is supplied to each of the speaker devices 31 to 34 to output (sound) the audio signal.

  As control of the correction processing in the DSP 23 by the control unit 26, in this example, control based on the result of analyzing the audio signal picked up by the microphone 42 is performed. That is, in this example, the microphone 42 is connected to the system, and the microphone 42 is arranged so as to pick up the audio output from the speaker devices 31 to 34. The microphone 42 may be connected only when necessary as a detachable configuration. The audio signal obtained by the microphone 42 is supplied to the analog / digital converter 29 via the buffer amplifier 41 to be converted into a digital audio signal, and the converted digital audio signal is supplied to the analysis unit 28. The analysis unit 28 analyzes the supplied audio signal.

  As the audio signal analysis in the analysis unit 28, the audio signal obtained by the microphone 42 is compared with a reference audio signal prepared in advance, and the amount of decrease in sensitivity for each level is analyzed. As described later, the sensitivity degradation analyzed in this example does not depend much on the frequency (that is, there is little change depending on the frequency), so only the signal of a specific frequency may be analyzed. Detailed analysis may be performed for each band. In this way, the input / output characteristics of the speaker devices 31 to 34 connected to the system can be analyzed by comparing the reference audio signal and the audio signal picked up by the microphone.

  Then, the control unit 26 determines an analysis result of the speaker device, and executes correction processing in the DSP 23 so as to correct a decrease in output sensitivity of the speaker device below a predetermined level of sensitivity to input. The correction state data based on the analysis result is stored in the memory 27, for example, until the correction state value is updated.

  An example of the analysis of the audio signal in the analysis unit 28 will be described. For example, it is assumed that the impulse signal shown as the waveform w0 in FIG. 3 is supplied from the amplifier device 20 to the speaker device and reproduced as the reference audio signal. At this time, the audio signal waveform picked up by the microphone 42 is, for example, the waveform w1 shown in FIG. 3, and it is assumed that when the level is lowered below a predetermined level compared to the waveform w0, a significant decrease in sensitivity appears. At this time, it is analyzed how much sensitivity is lowered below which level.

  FIG. 4 shows an example of an analysis state when a fundamental wave of a specific frequency f1 and its harmonics f2, f3... Are reproduced. Since the level of the fundamental wave is high, an output level corresponding to the input level is detected. For example, a signal component having a frequency f2 that is twice as high is detected to have a sensitivity d1 lower than the original level. Similarly, for example, a signal component having a frequency f3 which is three times lower than the original level is detected by a sensitivity d2.

  Such a decrease in sensitivity is detected and analyzed, and a correction process that compensates for the decrease in sensitivity is performed on a signal component at a level at which the analyzed sensitivity decreases, so that the signal is output from the speaker devices 31 to 34. The audio signal becomes a good reproduction sound faithful to the input audio signal.

  FIG. 5 is a diagram illustrating a state in which audio signals are output from the speaker devices 31 to 34 by correction with such characteristics as output characteristics from a low frequency to a high frequency at a plurality of stages of signal levels. FIG. 5A is a diagram showing output characteristics (that is, uncorrected output characteristics) of the speaker devices 31 to 34 themselves of this example. FIG. 5A is the same as the speaker characteristic shown in FIG. 11B as the background art. That is, as shown in FIG. 5 (a), for the levels L1, L2, and L3 with high output levels, output characteristics almost equal to the ideal characteristics are secured, but for the output characteristics with the lowest level L4, It is a level that is lowered in any frequency band by the sensitivity α from the originally required level.

  Here, by performing the correction in the amplifier device 20, as shown in FIG. 5B, the output characteristics of the signal input to the amplifier device 20 are the levels L1, L2, and L3 with high output levels. Although the input level is not changed, the output characteristic of the lowest level L4 is a level that is increased from the original level by the sensitivity β in any frequency band. Here, the increased sensitivity β is optimally set based on actual measurement and analysis so that the sensitivity α decreases at the speaker devices 31 to 34.

  With the above characteristics, the audio signal processed by the amplifier device 20 is output from the speaker devices 31 to 34, and the characteristics of the audio output from the speaker devices 31 to 34 are shown in FIG. As shown in the figure, the four levels L1, L2, L3, and L4 are flat at almost equal intervals from low to high, and are almost equal to the ideal characteristics shown in FIG. Is a good characteristic that matches regardless of the level in all frequency bands.

  FIG. 6 is a diagram illustrating a characteristic example corrected by the DSP 23 at a specific frequency. In FIG. 6, a characteristic a indicated by a broken line is a characteristic having a linearity in which the increase / decrease in the input level and the increase / decrease in the output level are linearly proportional and are shown for reference. The characteristics b, c, and d indicated by solid lines are examples of three characteristics corrected by the DSP 23 of this example.

  As shown by these characteristics b, c, d, the correction characteristics in the DSP 23 of this example are characteristics in which linearity in which the increase / decrease in the input level and the increase / decrease in the output level are linearly proportional within a predetermined level or more. (That is, a characteristic that substantially matches the characteristic a) (that is, the input level and the output level are made equal). In a range below a predetermined level, the output level is lower than the input level, and the characteristic indicated by a curve that does not have linearity such that the rate of increase is higher than the linear input / output characteristic a as the level is lower. It is supposed to be.

  Here, in this example, since the characteristic of the curve is obtained based on the result of the actual analysis from the reproduced sound from the speaker device, for example, one of the characteristics b, c, and d is selected. Alternatively, when the curve obtained from the analysis result is different from the characteristics b, c, d, another characteristic is set. The characteristics b, c, and d shown in FIG. 6 indicate characteristics at a specific frequency. In the case of this example, the characteristics b, c, and d are almost the same in all audible bands that can be reproduced by the speaker. It has characteristics. Further, the correction curve obtained from the analysis result may be adjusted to some extent by a user operation. As an adjustment by the user operation, for example, when the adjustment amount is 0, the curve obtained from the analysis result is set as a correction curve as it is, and when the adjustment is made in the + direction, the correction curve is made a tighter curve. When the adjustment is made in the-direction, it is conceivable that the correction curve is a gentler curve.

  Next, a processing procedure when the correction state is set by performing an analysis based on the audio signal input from the microphone 42 connected to the amplifier device 20 of this example will be described with reference to the flowchart of FIG. First, an audio signal serving as a reference for measurement prepared in the memory 27 or the like is output from the speaker device (step ST11). The output audio signal is input by the microphone 42 and converted into digital data, which is taken into the analysis unit 28 (step ST12). Then, the captured audio data is compared with the reference audio data to analyze the decrease in sensitivity for each level (step ST13). Based on the analyzed result, the control unit 26 calculates the sensitivity correction amount of the low-level signal (step ST14), stores the calculated correction amount in the memory 27 (step ST15), and sets the correction state. Exit.

  Next, a processing example when outputting (reproducing) the audio signal supplied from the audio signal source 10 using the correction state data set in this way will be described with reference to the flowchart of FIG. To do. First, when the playback system is powered on (step ST21), the control unit 26 reads the correction amount data stored in the memory 27 and causes the DSP 23 to set the correction amount (step ST22). And the control part 26 judges whether there exists operation which adjusts the correction | amendment state by user operation (step ST23). If it is determined that there is an operation for adjusting the correction state, the correction amount set in the DSP 23 is changed (corrected) based on which adjustment operation (step ST24). Then, the data stored in the memory 27 is updated with the changed correction amount (step ST25).

  By correcting the reproduction characteristics from the speaker device in this way, the audio signal input from the audio signal source 10 or the like is output with faithful characteristics, and the reproduction sound quality can be improved. Such reproduction characteristics are completely different from the process of enhancing a signal in a specific frequency band, such as the conventionally known loudness control, regardless of the level, and faithfully reproduces the input audio signal. It is a characteristic.

  In addition, in the case of this example, since the correction is made based on the result of picking up and analyzing the sound actually output from the speaker device, unlike the case where the correction characteristics are prepared in advance, the characteristics of the individual speaker devices are changed. Even if there is variation, it can be corrected accurately. Also, the input / output characteristics may vary depending on the installation environment of the speaker device, but such differences can be dealt with. In particular, as in the installation example shown in FIG. 1, for example, when installed in a car as a car stereo, the playback environment may be completely different depending on the type of car installed and the installation position of the speaker device. Automatic correction as in the example is very effective.

  Note that the playback system of this example can be applied to various audio playback systems. In the example shown in FIG. 1, the audio signal source 10, the amplifier device 20, and the speaker devices 31 to 34 are configured separately. However, an integrated system (apparatus) may be used. Or it is good also as a structure which can be connected to the amplifier apparatus which does not have a correction process function by incorporating the correction | amendment means which correct | amends the characteristic of the speaker apparatus in the inside of a single speaker apparatus. Alternatively, the same correction may be applied to the audio signal itself output from the audio signal source 10.

  In the above-described embodiment, the car stereo playback system is used, but the present invention can also be applied to various audio playback systems such as a general indoor playback system. Even in the case of a car stereo playback system, the number of speaker devices connected is not limited to the above-described example.

  In the above-described embodiment, the analysis from the speaker device is performed in advance using a reference audio signal, and the calculated correction characteristic is set. For example, the reproduced sound from the speaker device is set. Is it necessary to correct the correction amount by always comparing the input audio signal to the amplifier device and the output sound from the speaker device when the audio signal is actually played back and the microphone that picks up the sound is always connected? Monitoring may be performed to correct the correction amount as needed. In such a case, it is possible to appropriately adjust the correction amount only from the actual reproduction situation without preparing a reference audio signal for setting the correction amount first.

  In the above-described embodiment, the correction characteristics are calculated and set collectively assuming that the reproduction characteristics of a plurality of speaker devices prepared are the same. For example, the reference audio signal is one by one. Individually output from each speaker device, individually analyze based on the playback sound of each speaker device, and set different correction characteristics for each speaker device based on the individually analyzed results You may make it make it. By doing in this way, the reproduction characteristics of each speaker device are more strictly corrected, and better reproduction characteristics can be obtained.

It is a block diagram which shows the system configuration example by one embodiment of this invention. It is a block diagram which shows the structural example by one embodiment of this invention. It is the wave form diagram which showed the example of the characteristic of the speaker apparatus by one embodiment of this invention. It is the characteristic view which showed the example of a measurement of the characteristic of the speaker apparatus by one embodiment of this invention. It is the characteristic view which showed the example of the correction state by one embodiment of this invention with the output sensitivity for every frequency. It is a characteristic view showing an example of correction characteristics according to an embodiment of the present invention. It is the flowchart which showed the example of the setting of the correction amount by one embodiment of this invention. It is the flowchart which showed the example of a process at the time of the audio output by one embodiment of this invention. It is explanatory drawing which showed the example of the output waveform of the conventional speaker. It is explanatory drawing which showed the example of the signal level of the conventional speaker. It is explanatory drawing which showed the output characteristic example (a) of the ideal speaker, and the output characteristic example (b) of the conventional speaker. It is explanatory drawing which showed the example of the input / output characteristic of the conventional speaker.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Audio signal source, 20 ... Amplifier apparatus, 21 ... Audio signal input terminal, 22 ... Analog / digital converter, 23 ... DSP (digital signal processor), 24 ... Digital / analog converter, 25 ... Amplifier, 26 ... Control unit, 27 ... Memory, 28 ... Analysis unit, 29 ... Analog / digital converter, 41 ... Amplifier, 42 ... Microphone

Claims (4)

An audio signal processing method for performing correction processing for outputting an input audio signal from a speaker device having predetermined input / output characteristics,
Input a reference audio signal to the speaker device, pick up the output of the reference audio signal with a microphone,
Compare the audio signal obtained with the microphone and the reference audio signal, analyze the amount of decrease in sensitivity for each level,
An audio signal processing method comprising: performing a correction process to compensate for a decrease in sensitivity on a signal component of a level at which the analyzed sensitivity decreases in an audio signal supplied to the speaker device. In an audio reproduction system for outputting an input or reproduced audio signal from a speaker device,
A microphone that picks up an audio signal output from the speaker device;
An analysis means for comparing an audio signal obtained by the microphone with an audio signal supplied to the speaker device, and analyzing an amount of decrease in sensitivity for each level;
The input or reproduced audio signal is used as an audio signal for driving the speaker device, and correction processing that compensates for the decrease in sensitivity is performed on the signal component of the level at which the sensitivity is analyzed analyzed by the analysis unit. An audio reproduction system comprising an audio signal processing means. The audio reproduction system according to claim 2, wherein
The audio reproduction system is characterized in that the correction processing in the audio signal processing means performs correction processing that compensates for a decrease in output sensitivity substantially uniformly for each level within almost all frequency bands output by the speaker device. . The audio reproduction system according to claim 2, wherein
An audio reproduction system comprising storage means for storing the amount of decrease in sensitivity for each level analyzed by the analysis means.

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