Audio playback system, audio playback method, and program

Abstract

An audio playback system (1) comprises a first housing (100), a first speaker (160) provided in the first housing (100), a first microphone (130) provided in the first housing (100), a processor (110), and an equalizer (120), wherein: the processor (110) causes the first speaker (160) to output a first test audio, acquires a first sound pickup signal indicating the first test audio picked up by the first microphone (130), calculates a first frequency characteristic of the first sound pickup signal, estimates the placement of the first housing (100) in space on the basis of the first frequency characteristic, and determines a first correction parameter on the basis of the placement of the first housing (100); the equalizer (120) corrects the frequency characteristic of the input audio signal using the first correction parameter to generate a first corrected audio signal; and the first speaker (160) outputs audio based on the first corrected audio signal.

Description

Audio playback system, audio playback method, and program

[0001] The present disclosure relates to audio reproduction systems and the like.

[0002] Patent Document 1 discloses a technique for correcting the sound pressure level of a speaker for each frequency band so that the sound pressure level from the speaker at the user's listening position has a preset characteristic across all frequency bands.

[0003] Japanese Patent Application Publication No. 1-130608

[0004] However, in order to correct the frequency characteristics of a signal picked up at a user's listening position, as with the technology disclosed in Patent Document 1, the user needs to install a microphone at the listening position, pick up the sound reproduced from the speaker with the microphone, and calculate correction parameters for correcting the frequency characteristics of the input sound signal to be input to the sound reproduction system. In other words, the user needs to prepare special equipment such as a microphone in addition to what is required for normal playback. Furthermore, collecting sound at the listening position and calculating the correction parameters requires skill and specialized knowledge. This makes it difficult to achieve the performance (sound quality) intended by the designer in the user's space.

[0005] Therefore, the present disclosure provides an audio playback system and the like that can easily achieve the performance intended by the designer.

[0006] The audio reproduction system of the present disclosure comprises a first housing installed in a space, a first speaker provided in the first housing, a first microphone provided in the first housing, a processor, and an equalizer unit, wherein the processor causes the first speaker to output a first test audio based on a test signal, acquires a first picked-up signal indicating the first test audio picked up by the first microphone, calculates a first frequency characteristic of the first picked-up signal, estimates the position of the first housing in the space based on the first frequency characteristic, and determines a first correction parameter based on the position of the first housing, the equalizer unit generates a first corrected audio signal by correcting the frequency characteristic of an input audio signal input to the audio reproduction system using the first correction parameter, and the first speaker outputs audio based on the first corrected audio signal.

[0007] The audio reproduction method according to the present disclosure is an audio reproduction method executed by an audio reproduction system, the audio reproduction system comprising a first housing installed in a space, a first speaker provided in the first housing, and a first microphone provided in the first housing, and the audio reproduction method includes outputting a first test audio based on a test signal to the first speaker, acquiring a first picked-up signal indicating the first test audio picked up by the first microphone, calculating a first frequency characteristic of the first picked-up signal, estimating the position of the first housing in the space based on the first frequency characteristic, determining a first correction parameter based on the position of the first housing, correcting the frequency characteristic of an input audio signal input to the audio reproduction system using the first correction parameter to generate a first corrected audio signal, and outputting audio based on the first corrected audio signal from the first speaker.

[0008] A program according to the present disclosure is a program for causing a computer to execute the above-described audio playback method.

[0009] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0010] According to the audio reproduction system and the like of the present disclosure, it is possible to easily achieve the performance intended by the designer.

[0011] 1 is a diagram illustrating an example of a configuration of an audio reproduction system according to a first embodiment. FIG. 2 is a block diagram illustrating an example of a correction parameter generator according to the first embodiment. FIG. 3 is a diagram illustrating a "Free" arrangement. FIG. 4 is a diagram illustrating a "Wall" arrangement. FIG. 5 is a diagram illustrating a "Corner" arrangement. FIG. 6 is a diagram illustrating a "Shelf" arrangement. FIG. 7 is a graph illustrating an example of a difference between a first frequency characteristic and a first reference frequency characteristic for each actual arrangement of a first housing. FIG. 8 is a block diagram illustrating another example of a correction parameter generator according to the first embodiment. FIG. 9 is a diagram illustrating an example of a configuration of an audio reproduction system according to a second embodiment. FIG. 10 is a graph illustrating an example of a difference between a second frequency characteristic and a second reference frequency characteristic for each actual arrangement of a slave housing when the arrangement of a master housing is "Corner". FIG. 11 is a graph illustrating an example of a difference between a second frequency characteristic and a second reference frequency characteristic for each actual arrangement of a slave housing when the arrangement of a master housing is "Free". FIG. 12 is a graph illustrating an example of a difference between a second frequency characteristic and a second reference frequency characteristic for each actual arrangement of a slave housing when the arrangement of a master housing is "Shelf". 10 is a graph showing an example of the difference between the second frequency characteristic and the second reference frequency characteristic for each actual arrangement of the slave housings when the arrangement of the master housing is "Wall". FIG. 11 is a diagram showing an example of the configuration of an audio reproduction system according to embodiment 3. FIG. 12 is a flowchart showing an example of an audio reproduction method according to another embodiment.

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, more detailed description than necessary may be omitted. For example, detailed description of well-known matters or redundant description of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

[0013] The inventors have provided the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0014] (First Embodiment) Hereinafter, an audio reproduction system according to a first embodiment will be described with reference to Figs.

[0015] FIG. 1 is a diagram showing an example of the configuration of an audio reproduction system 1 according to the first embodiment.

[0016] The audio reproduction system 1 is a system for outputting from a first speaker 160 an audio signal input to the audio reproduction system 1 from a sound source player connected to an input terminal 140. The sound source player may be built into the audio reproduction system 1. That is, the sound source player may be externally attached to the audio reproduction system 1 as a component outside the audio reproduction system 1, or may be built into the audio reproduction system 1 as a component of the audio reproduction system 1. The audio reproduction system 1 has a function for optimizing the frequency characteristics of an audio signal obtained by collecting sound at a listening position (hereinafter also referred to as an audio signal at the listening position), and this function will be described below.

[0017] The audio reproduction system 1 includes a first housing 100 , a processor 110 , an equalizer 120 , a first microphone 130 , an input terminal 140 , an amplifier 150 , and a first speaker 160 .

[0018] The audio reproduction system 1 is a computer including a processor 110 (microprocessor) and a memory 180. The audio reproduction system 1 may also include a communication interface and a user interface. The memory 180 is a read-only memory (ROM) and a random access memory (RAM), and can store programs executed by the processor 110 and data related to processing. As shown in FIG. 1 , the processor 110 includes a test signal generator 111, a signal switcher 112, a sound pickup measurement device 113, and a correction parameter generator 114. In other words, these components are realized by the processor 110 executing programs stored in the memory 180.

[0019] For example, the memory 180 stores data related to processing, such as a reference frequency characteristic (specifically, a first reference frequency characteristic), system information, or a correction parameter group, as shown in Fig. 2 (described later). Note that the program executed by the processor 110 and the data related to processing may be stored in different memories.

[0020] For example, in the first embodiment, the audio reproduction system 1 is a computer (device) in one housing, and there is one channel of input to the audio reproduction system 1 and one channel of output from the audio reproduction system 1. For example, the audio reproduction system 1 includes only one set of a first housing 100, a processor 110, an equalizer 120, a first microphone 130, an input terminal 140, an amplifier 150, and a first speaker 160, and reproduces monaural audio.

[0021] The input to the audio reproduction system 1 may be multi-channel, and the output from the audio reproduction system 1 may be multi-channel. In this case, the audio reproduction system 1 can reproduce stereo or surround sound. For example, the audio reproduction system 1 may include multiple sets of the first housing 100, the processor 110, the equalizer 120, the first microphone 130, the input terminal 140, the amplifier 150, and the first speaker 160. These components may be arranged in a single housing, thereby forming the audio reproduction system 1 as a single-housing device. Alternatively, the audio reproduction system 1 may include multiple sets of the first housing 100, the processor 110, the equalizer 120, the first microphone 130, the input terminal 140, the amplifier 150, and the first speaker 160, and the audio reproduction system 1 may be a system consisting of multiple housings. When the input to the audio reproduction system 1 is multi-channel and the output from the audio reproduction system 1 is multi-channel, the number of input channels may differ from the number of output channels. For example, the number of output channels can be increased or decreased by appropriately combining the inputs.

[0022] The first housing 100 is placed in a space such as a user's room. The first speaker 160 is provided in the first housing 100. The first microphone 130 is provided in the first housing 100. In other words, the first housing 100 is provided with not only a speaker but also a microphone.

[0023] Since the frequency characteristics of the audio signal at the listening position change from the frequency characteristics of the input audio signal depending on the placement of the first housing 100 in space, as described below, the audio reproduction system 1 has the function of estimating the placement of the first housing 100 and determining a first correction parameter for correcting the frequency characteristics of the audio signal at the listening position based on the estimated placement of the first housing 100.

[0024] The equalizer 120 is an example of an equalizer unit, and generates a corrected audio signal by correcting the frequency characteristics of an input audio signal input to the audio reproduction system 1, and outputs the corrected audio signal to the first speaker 160. For example, the equalizer 120 is a parametric equalizer, and can adjust the center frequency of the input audio signal, the width of the frequency band to be adjusted, and the volume. For example, an amplifier 150 is provided between the equalizer 120 and the first speaker 160, and audio based on the corrected audio signal amplified by the amplifier 150 can be output from the first speaker 160. Note that the equalizer 120 may be realized by the processor 110. In other words, the equalizer 120 may be a component of the processor 110.

[0025] The test signal generator 111, signal switch 112, sound collection measurement device 113, and correction parameter generator 114 are realized by a processor 110 that executes a program stored in memory 180. The processor 110 has a mode for optimizing the frequency characteristics of an audio signal at the listening position and a mode for reproducing normal audio (an input audio signal from a sound source player). In the mode for optimizing the frequency characteristics of an audio signal at the listening position, the test signal generator 111 generates a test signal, and the signal switch 112 connects the test signal generator 111 to the equalizer 120 to output the test signal to the equalizer 120. The test signal may be, for example, a sine wave signal having frequency components across an audio band (e.g., 20 Hz to 20 kHz), a time-stretched pulse (TSP) signal, or white noise. In the normal audio playback mode, the test signal generator 111 does not generate a test signal, and the signal switcher 112 connects the input terminal 140 to the equalizer 120 to output the input audio signal to the equalizer 120 .

[0026] In a mode for optimizing the frequency characteristics of the audio signal at the listening position, the equalizer 120 does not perform correction. That is, the test signal generated by the test signal generator 111 is not corrected by the equalizer 120. The processor 110 causes the first speaker 160 to output a first test sound based on the test signal generated by the test signal generator 111. As a result, the first test sound is output from the first speaker 160 into the space in which the first housing 100 is installed.

[0027] The first test sound output from the first speaker 160 into the space in which the first housing 100 is installed is picked up by the first microphone 130 provided in the first housing 100. For example, the first microphone 130 picks up, as the first test sound, a direct sound from the first speaker 160 and a reflected sound that is the sound output from the first speaker 160 reflected by objects such as walls, ceilings, floors, or furniture in the space in which the first housing 100 is installed (hereinafter referred to as walls, etc.).

[0028] The sound collection measurement device 113 acquires a first collected sound signal indicating the first test sound collected by the first microphone 130. Note that the sound collected by the first microphone 130 at the timing when the first test sound is output from the first speaker 160 is a part of the first test sound, including direct sound that reaches the first microphone 130 directly and reflected sound that reaches the first microphone 130 after reflecting off walls and the like. Although this sound is different from the first test sound output by the first speaker 160, this sound is also referred to as the first test sound for convenience. Also, for convenience, the sound signal collected by the first microphone 130 based on the sound referred to as the first test sound is referred to as the first collected sound signal. The sound collection measurement device 113 outputs the acquired first collected sound signal to the correction parameter generator 114.

[0029] The correction parameter generator 114 determines a first frequency characteristic of the first collected sound signal, estimates the arrangement of the first housing 100 in space based on the determined first frequency characteristic, and determines a first correction parameter based on the estimated arrangement of the first housing 100. Details of the correction parameter generator 114 will be described later with reference to FIG. 2. The correction parameter generator 114 sets the determined first correction parameter in the equalizer 120.

[0030] Thereafter, in a mode for reproducing normal audio, the equalizer 120 generates a first corrected audio signal by correcting the frequency characteristics of the input audio signal input to the audio reproduction system 1 using the first correction parameter, and outputs audio based on the first corrected audio signal to the first speaker 160. In other words, audio based on the first corrected audio signal generated by correcting the frequency characteristics of the input audio signal using the first correction parameter is output from the first speaker 160, allowing the user to hear audio with improved frequency characteristics at the listening position.

[0031] Next, the correction parameter generator 114 will be described in detail with reference to FIG.

[0032] FIG. 2 is a block diagram showing an example of the correction parameter generator 114 according to the first embodiment.

[0033] 2, the correction parameter generator 114 includes a frequency characteristic analysis unit 115, a comparison analysis unit 116, and a determination unit 117. The frequency characteristic analysis unit 115, the comparison analysis unit 116, and the determination unit 117 are realized by the processor 110 that executes a program stored in the memory 180, or the like.

[0034] The correction parameter generator 114 uses the first reference frequency characteristic stored in the memory 180 to estimate the arrangement of the first enclosure 100 and determine the first correction parameter.

[0035] The frequency characteristic analysis unit 115 calculates a first frequency characteristic of a first collected sound signal that indicates the first test sound output from the first speaker 160 and collected by the first microphone 130. For example, the frequency characteristic analysis unit 115 calculates the first frequency characteristic of the first collected sound signal by performing an FFT (Fast Fourier Transform) on the first collected sound signal.

[0036] The comparison and analysis unit 116 estimates the location of the first housing 100 by comparing the first frequency characteristic with the first reference frequency characteristic stored in the memory 180. Note that the comparison and analysis unit 116 may use system information including information on the frequency characteristic of the first microphone 130 when estimating the location of the first housing 100. Here, a method for estimating the location of the first housing 100 will be described with reference to FIGS. 3A to 3D and 4.

[0037] FIG. 3A is a diagram for explaining the arrangement of "Free."

[0038] FIG. 3B is a diagram for explaining the arrangement of the "Wall."

[0039] FIG. 3C is a diagram for explaining the arrangement of "Corner."

[0040] FIG. 3D is a diagram for explaining the arrangement of the "Shelf."

[0041] 3A to 3D show examples of the arrangement of two housings each equipped with a speaker. 3A to 3D show top views of the space (views of the space from the ceiling side), and 3D is a front view of the bookshelf.

[0042] FIG. 3A shows a "Free" arrangement, in which a housing in which a speaker is provided is placed at a position away from a wall or the like of a space.

[0043] FIG. 3B shows a "Wall" arrangement, in which the enclosure in which the speaker is mounted is placed close to one wall of the space.

[0044] 3C shows a "Corner" arrangement, in which the housing with the speaker is installed in a corner of a space. Specifically, in the "Corner" arrangement, the housing with the speaker is installed in a position close to both walls of the space.

[0045] FIG. 3D shows a "Shelf" arrangement, in which the enclosure with the speaker is placed on a bookshelf in the space.

[0046] For example, in a space such as a room, a plurality of predetermined arrangements are assumed for the arrangement of housings in which speakers are provided, as shown in Figures 3A to 3D. For example, the comparison analysis unit 116 estimates the arrangement of the first housing 100 by estimating which of the plurality of predetermined arrangements as shown in Figures 3A to 3D the arrangement of the first housing 100 is closest to.

[0047] FIG. 4 is a graph showing an example of the difference between the first frequency characteristic and the first reference frequency characteristic for each actual arrangement of the first housing 100. In FIG.

[0048] The first reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up a first reference test sound based on a test signal output from a first test speaker provided in a first test enclosure installed at a specific position in the test space, using a first test microphone provided in the first test enclosure.

[0049] The first test housing, the first test speaker, and the first test microphone are basically the same as the first housing 100, the first speaker 160, and the first microphone 130, and the first reference test sound is the same as the first test sound. When the first reference test sound is output from the first test speaker, the equalizer does not correct the test signal representing the reference test sound. The first reference frequency characteristic is a frequency characteristic calculated from the sound signal picked up by the first test microphone when the first reference test sound is output from the first test speaker when the first test housing is in the standard "Free" arrangement (specifically, the average arrangement among the "Free" arrangements).

[0050] For example, the designer of the audio reproduction system 1 designs the entire audio reproduction system, including the speaker characteristics, so that the frequency characteristics of the audio signal are optimized in a standard "free" arrangement, and then calculates the first reference frequency characteristic from a picked-up signal obtained by picking up a first reference test audio based on a test signal with a first test microphone provided in a first test housing. At this time, no correction is made by an equalizer, but the first reference audio with the optimal frequency characteristics is output from the first test speaker in the standard "free" arrangement.

[0051] In the first embodiment, the first test housing is placed in the "Free" position shown in Fig. 3A. That is, the first reference frequency characteristic is calculated when the first test housing is placed in the "Free" position.

[0052] For example, the comparison and analysis unit 116 calculates the difference in a predetermined frequency band (e.g., 50 Hz to 6 kHz) between a first reference frequency characteristic calculated in advance using a first test housing installed at a specific position in the test space and the first frequency characteristic calculated in the user's space. When the arrangement of the first housing 100 in the user's space corresponds to "Free" (an arrangement close to "Free"), the difference in the predetermined frequency band between the first reference frequency characteristic and the first frequency characteristic approaches zero across the predetermined frequency band, as shown in the upper left graph of FIG.

[0053] When the arrangement of the first housing 100 in the user's space corresponds to the "Wall" (i.e., is close to the "Wall"), the difference between the first reference frequency characteristic and the first frequency characteristic in a predetermined frequency band occurs to some extent across the predetermined frequency band, as shown in the graph in the upper right of Figure 4.

[0054] In the user's space, when the arrangement of the first housing 100 corresponds to a "corner" (an arrangement close to a "corner"), the difference between the first reference frequency characteristic and the first frequency characteristic in a specified frequency band is larger across the specified frequency band than when the arrangement of the first housing 100 corresponds to a "wall," as shown in the graph in the lower left of Figure 4.

[0055] In the user's space, when the arrangement of the first housing 100 corresponds to a "Shelf" (an arrangement close to a "Shelf"), the difference between the first reference frequency characteristic and the first frequency characteristic in a specified frequency band is larger across the specified frequency band than when the arrangement of the first housing 100 corresponds to a "Corner," as shown in the graph in the lower right of Figure 4.

[0056] In this way, the comparison analysis unit 116 estimates the placement depending on the magnitude of the difference. Specifically, if the difference is almost 0, it determines it to be "Free," and as the difference increases, it determines it to be "Wall," "Corner," or "Shelf."

[0057] For example, the comparison and analysis unit 116 smoothes each of the first reference frequency characteristic and the first frequency characteristic using an octave band filter such as a ⅓ octave band filter, then normalizes the amplitude level at a signal level of 1 kHz and converts the amplitude level into decibel units. Normalizing the amplitude level makes it possible to appropriately compare the first reference frequency characteristic and the first frequency characteristic even if there is a difference in the sound pickup levels between the first reference frequency characteristic and the first frequency characteristic.

[0058] For example, the comparison / analysis unit 116 estimates the arrangement of the first housing 100 by adding up the absolute values ​​of the differences between the first reference frequency characteristic and the first frequency characteristic for each frequency in a predetermined frequency band and determining whether the sum falls within a numerical range set for each of a plurality of predetermined arrangements (e.g., a “Free” arrangement, a “Wall” arrangement, a “Corner” arrangement, and a “Shelf” arrangement). The numerical ranges set for each of the plurality of predetermined arrangements do not overlap. For example, if the sum falls within the numerical range set for the “Free” arrangement, it can be estimated that the arrangement of the first housing 100 is the “Free” arrangement. For example, if the sum falls within the numerical range set for the “Wall” arrangement, it can be estimated that the arrangement of the first housing 100 is the “Wall” arrangement. For example, if the sum falls within the numerical range set for the “Corner” arrangement, it can be estimated that the arrangement of the first housing 100 is the “Corner” arrangement. For example, if the added value is included in the numerical range set for the "Shelf" arrangement, it can be estimated that the arrangement of the first housing 100 is the "Shelf" arrangement.

[0059] The comparison result between the first reference frequency characteristic and the first frequency characteristic changes according to changes in the arrangement of the first housing 100. In other words, there is a correlation between the comparison result between the first reference frequency characteristic and the first frequency characteristic and the arrangement of the first housing 100. Therefore, by comparing the first reference frequency characteristic and the first frequency characteristic, it is possible to easily estimate the arrangement of the first housing 100.

[0060] Returning to the explanation of FIG. 2 , the determination unit 117 determines, as the first correction parameter, a correction parameter that is predetermined for a predetermined arrangement that is estimated as the arrangement of the first housing 100 from among a plurality of predetermined arrangements (e.g., a "Free" arrangement, a "Wall" arrangement, a "Corner" arrangement, and a "Shelf" arrangement). As shown in FIG. 2 , the memory 180 stores a group of correction parameters that are predetermined for a plurality of predetermined arrangements. For example, the memory 180 stores a correction parameter that is predetermined for the "Free" arrangement, a correction parameter that is predetermined for the "Wall" arrangement, a correction parameter that is predetermined for the "Corner" arrangement, and a correction parameter that is predetermined for the "Shelf" arrangement.

[0061] The designer of the audio reproduction system 1 can determine in advance optimal correction parameters for each of a plurality of predetermined layouts by conducting experiments, simulations, or the like. Therefore, the first correction parameters can be easily determined by using the correction parameters predetermined for the predetermined layouts estimated as the layout of the first housing 100 as the first correction parameters. For example, if the layout of the first housing 100 is estimated to be the "Free" layout among the plurality of predetermined layouts (specifically, a layout close to the "Free" layout), the correction parameters predetermined for the "Free" layout among the correction parameter group can be used as the first correction parameters.

[0062] It should be noted that the first frequency characteristic used to estimate the arrangement of the first housing 100 may be used to determine the first correction parameter. This will be described with reference to FIG.

[0063] Fig. 5 is a block diagram showing another example of the correction parameter generator 114 according to embodiment 1. The correction parameter generator 114 shown in Fig. 5 differs from the correction parameter generator 114 shown in Fig. 2 in that it includes a determination unit 117a instead of the determination unit 117, and that the memory 180 does not store a correction parameter group. As the other points are the same as those of the correction parameter generator 114 shown in Fig. 2, a description thereof will be omitted.

[0064] No correction parameter group is stored in the memory 180. That is, the determination unit 117a determines the first correction parameter without using the correction parameter group.

[0065] The determination unit 117a determines a first correction parameter that reduces the difference between the first reference frequency characteristic and the first frequency characteristic in a predetermined frequency range for a predetermined arrangement estimated as the arrangement of the first housing 100 from among a plurality of predetermined arrangements.

[0066] For example, the first reference frequency characteristic is the frequency characteristic of a first reference test sound based on a test signal, calculated in a state where the equalizer is designed so that the frequency characteristic of the sound signal is optimized at the listening position of the sound reproduced from the sound reproduction system 1. Therefore, by determining a first correction parameter that reduces the difference between the first frequency characteristic and the first reference frequency characteristic in a predetermined frequency band, it is possible to improve the frequency characteristic of the sound signal even at the listening position in the user's space.

[0067] However, the first reference frequency characteristic is a frequency characteristic calculated when the first test housing is in a specific position (the "Free" position), and the position of the first test housing may differ from the position of the first housing 100. Therefore, the frequency range in which the first reference frequency characteristic and the first frequency characteristic should be compared will differ depending on the position of the first housing 100.

[0068] In response to this, the designer can determine in advance, for each of a plurality of predetermined arrangements, the frequency range in which the first reference frequency characteristic and the first frequency characteristic should be compared, by performing an experiment, a simulation, etc. Therefore, it is possible to determine the first correction parameter according to the arrangement of the first housing 100.

[0069] As described above, the first microphone 130 required to determine the first correction parameter for the first speaker 160 provided in the first housing 100 is pre-installed in the first housing 100. This eliminates the need for the user to separately prepare special equipment, such as a microphone, in addition to that required for normal playback. Furthermore, the location of the first housing 100 is automatically estimated from the first frequency characteristics of the first collected signal indicating the first test sound collected by the first microphone 130, and the first correction parameter is automatically determined from the estimated location of the first housing 100. This eliminates the need for the user to have the skills and expertise to collect an audio signal at the listening position and determine the correction parameter. Therefore, even a user without specialized knowledge can automatically improve the frequency characteristics at the listening position with a single touch, making it possible to easily achieve the performance intended by the designer.

[0070] Second Embodiment Next, an audio reproduction system according to a second embodiment will be described with reference to FIG. 6 and FIGS. 7A to 7D.

[0071] FIG. 6 is a diagram showing an example of the configuration of an audio reproduction system 2 according to the second embodiment.

[0072] The audio reproduction system 2 is a system for outputting audio based on an input audio signal input to the audio reproduction system 2 from a sound source player connected to the input terminal 140, from a first speaker 160 and a second speaker 230. The sound source player may be built into the audio reproduction system 2. That is, the sound source player may be externally attached to the audio reproduction system 2 as a component outside the audio reproduction system 2, or may be built into the audio reproduction system 2 as a component of the audio reproduction system 2. The audio reproduction system 2 has a function for optimizing the frequency characteristics of the audio signal at the listening position, and this function will be described below.

[0073] The audio playback system 2 includes a first housing 101, a processor 110a, an equalizer 120a, a first microphone 130, an input terminal 140, an amplifier 150, a first speaker 160, and a first communication I / F (interface) 170, as well as a second housing 201, a second communication I / F 210, an amplifier 220, and a second speaker 230.

[0074] Note that, with regard to the estimation of the arrangement of the first housing 101, the determination of the first correction parameter, and the operation during playback related to the sound output from the first speaker 160, explanations of the same parts as in the first embodiment will be omitted, and the explanation here will focus on the estimation of the arrangement of the second housing 201, the determination of the second correction parameter, and the operation during playback related to the sound output from the second speaker 230. Also, explanations of components with the same reference numerals and terms with the same names as in the first embodiment may be omitted.

[0075] The audio reproduction system 2 is a computer including a processor 110a (microprocessor), a memory 180, a communication interface, etc. The audio reproduction system 2 may also include a user interface. As shown in Fig. 6, the processor 110a includes a test signal generator 111a, a signal switcher 112, a sound pickup measurement device 113a, and a correction parameter generator 114a. In other words, these components are realized by the processor 110a, etc., which execute a program stored in the memory 180.

[0076] For example, memory 180 stores data related to processing such as reference frequency characteristics, system information, or correction parameter groups, as in the first embodiment, except that as the reference frequency characteristics, a first reference frequency characteristic for first housing 101 and a second reference frequency characteristic for second housing 201 are stored.

[0077] For example, the audio reproduction system 2 operates with the first housing 101 provided with the processor 110a as the master housing and the second housing 201 as the slave housing. Alternatively, the master housing and the slave housing may be arranged in a single housing, so that the audio reproduction system 2 is an apparatus in a single housing.

[0078] The first housing 101 is a component corresponding to the first housing 100 of the first embodiment, and a description that overlaps with the first embodiment will be omitted.

[0079] The second housing 201 is installed in the space where the first housing 101 is installed. The second speaker 230 is provided in the second housing 201.

[0080] Since the frequency characteristics of the audio signal at the listening position change from the frequency characteristics of the input audio signal depending on the placement of the second housing 201 in space, as described below, the audio reproduction system 2 has the function of estimating the placement of the second housing 201 and determining a second correction parameter for correcting the frequency characteristics of the audio signal at the listening position based on the estimated placement of the second housing 201.

[0081] The equalizer 120a is a component corresponding to the equalizer 120 of the first embodiment, and a description that overlaps with the first embodiment will be omitted.

[0082] In the second embodiment, a configuration is described in which a one-channel audio signal is input and audio based on that audio signal is output from each of the first speaker 160 of the first housing 101 and the second speaker 230 of the second housing 201. However, stereo audio may be reproduced by inputting a two-channel audio signal and outputting one of the signals from the first speaker 160 and the other from the second speaker 230. The same applies to a case in which there are three or more input channels and three or more housings (speakers). In this case, surround audio may be reproduced.

[0083] The first communication I / F 170 is a communication interface provided in the first housing 101 and capable of transmitting an audio signal. The first communication I / F 170 transmits the audio signal to the second communication I / F 210 in the second housing 201. The first communication I / F 170 does not need to have a receiving function. In other words, the first communication I / F 170 may have only a transmitting function.

[0084] The second communication I / F 210 is provided in the second housing 201 and is capable of receiving an audio signal from the first communication I / F 170. The first communication I / F 170 and the second communication I / F 210 may be connected wirelessly or by wire. The second communication I / F 210 does not need to have a transmission function. In other words, the second communication I / F 210 may have only a reception function.

[0085] The second speaker 230 outputs audio based on the audio signal received by the second communication I / F 210. For example, an amplifier 220 is provided between the second communication I / F 210 and the second speaker 230, and audio based on the corrected audio signal amplified by the amplifier 220 can be output from the second speaker 230.

[0086] The test signal generator 111 a, the signal switch 112, the sound collection measurement device 113 a, and the correction parameter generator 114 a are realized by the processor 110 a that executes a program stored in the memory 180.

[0087] In a mode for optimizing the frequency characteristics of the audio signal at the listening position, the equalizer 120a does not perform correction. In other words, the test signal generated by the test signal generator 111a is not corrected by the equalizer 120a. The processor 110a causes the first speaker 160 to output a first test sound based on the test signal generated by the test signal generator 111a. As a result, the first test sound is output from the first speaker 160 into the space in which the first housing 101 and the second housing 201 are installed. In addition, the test signal generator 111a causes the first communication I / F 170 to transmit a test signal to the second communication I / F 210, thereby causing the second speaker 230 to output a second test sound based on the test signal. As a result, the second test sound is output from the second speaker 230 into the space in which the first housing 101 and the second housing 201 are installed.

[0088] The second test sound output from the second speaker 230 into the space in which the first housing 101 and the second housing 201 are installed is picked up by the first microphone 130 provided in the first housing 101. For example, the first microphone 130 picks up, as the second test sound, a reflected sound that is the sound output from the second speaker 230 reflected by a wall or the like in the space in which the first housing 101 and the second housing 201 are installed.

[0089] It should be noted that the period during which the first test sound is output from the first speaker 160 does not overlap with the period during which the second test sound is output from the second speaker 230. If these periods overlap, the first microphone 130 will pick up the first test sound and the second test sound at the same time, making it difficult to distinguish between the first test sound and the second test sound.

[0090] The sound collection measurement device 113a acquires a first collected sound signal indicating the first test sound collected by the first microphone 130. The sound collection measurement device 113a also acquires a second collected sound signal indicating the second test sound collected by the first microphone 130.

[0091] The sound picked up by the first microphone 130 at the timing when the second test sound is output from the second speaker 230 is a part of the second test sound that includes direct sound that reaches the first microphone 130 directly and reflected sound that reaches the first microphone 130 after being reflected by a wall or the like, and although it is different from the second test sound output by the second speaker 230, this sound is also referred to as the second test sound for convenience. Also, for convenience, the sound picked up by the first microphone 130 based on the sound that is referred to as the second test sound is referred to as the second picked-up signal.

[0092] The sound collection measurement device 113a outputs the acquired first and second collected sound signals to the correction parameter generator 114a.

[0093] The correction parameter generator 114a calculates a first frequency characteristic of the first collected sound signal, estimates the arrangement of the first housing 101 in space based on the calculated first frequency characteristic, and determines a first correction parameter based on the estimated arrangement of the first housing 101. The correction parameter generator 114a also calculates a second frequency characteristic of the second collected sound signal, estimates the arrangement of the second housing 201 in space based on the calculated second frequency characteristic, and determines a second correction parameter based on the estimated arrangement of the second housing 201. Details of the correction parameter generator 114a will be described later. The correction parameter generator 114a sets the determined first correction parameter and second correction parameter in the equalizer 120a.

[0094] Thereafter, in a mode for reproducing normal audio, the equalizer 120a corrects the frequency characteristics of an input audio signal input to the audio reproduction system 2 using the first correction parameter to generate a first corrected audio signal, and outputs audio based on the first corrected audio signal to the first speaker 160. The equalizer 120a also corrects the frequency characteristics of an input audio signal input to the audio reproduction system 2 using the second correction parameter to generate a second corrected audio signal, and outputs the audio based on the second corrected audio signal to the second speaker 230 via the first communication I / F 170. In other words, audio based on the first corrected audio signal generated by correcting the frequency characteristics of the input audio signal using the first correction parameter is output from the first speaker 160, and audio based on the second corrected audio signal generated by correcting the frequency characteristics of the input audio signal using the second correction parameter is output from the second speaker 230, allowing the user to hear audio with improved frequency characteristics at the listening position.

[0095] Next, details of the correction parameter generator 114a will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of the correction parameter generator 114 according to the first embodiment, but in the description of the second embodiment, the correction parameter generator 114 shown in Fig. 2 is replaced with a correction parameter generator 114a.

[0096] The correction parameter generator 114a includes a frequency characteristic analysis unit 115, a comparison analysis unit 116, and a determination unit 117. The frequency characteristic analysis unit 115, the comparison analysis unit 116, and the determination unit 117 are realized by the processor 110a that executes a program stored in the memory 180, or the like.

[0097] The correction parameter generator 114a uses the first reference frequency characteristic for the first housing 101 and the second reference frequency characteristic for the second housing 201 stored in the memory 180 to estimate the arrangement of the first housing 101 and the second housing 201 and to determine the first correction parameter and the second correction parameter.

[0098] The frequency characteristic analysis unit 115 calculates a first frequency characteristic of a first collected sound signal that is output from the first speaker 160 and indicates the first test sound picked up by the first microphone 130, and a second frequency characteristic of a second collected sound signal that is output from the second speaker 230 and indicates the second test sound picked up by the first microphone 130. For example, the frequency characteristic analysis unit 115 calculates the first frequency characteristic of the first collected sound signal by performing an FFT on the first collected sound signal, and calculates the second frequency characteristic of the second collected sound signal by performing an FFT on the second collected sound signal.

[0099] The comparative analysis unit 116 estimates the location of the first housing 101 and estimates the location of the second housing 201 using the estimation result (i.e., the location of the first housing 101). Specifically, the comparative analysis unit 116 estimates the location of the first housing 101 by comparing the first frequency characteristic with the first reference frequency characteristic stored in the memory 180, and then estimates the location of the second housing 201 by comparing the second frequency characteristic with the second reference frequency characteristic stored in the memory 180, taking the estimation result into consideration. Note that the comparative analysis unit 116 may use system information including information regarding the frequency characteristic of the first microphone 130 when estimating the locations of the first housing 101 and the second housing 201. The method for estimating the location of the first housing 101 is the same as that described in the first embodiment, and therefore will not be described again. The method for estimating the location of the second housing 201 will be described using FIGS. 7A to 7D .

[0100] FIG. 7A is a graph showing an example of the difference between the second frequency characteristic and the second reference frequency characteristic for each actual placement of the slave housing (second housing 201) when the placement of the master housing (first housing 101) is “Corner.”

[0101] Figure 7B is a graph showing an example of the difference between the second frequency characteristic and the second reference frequency characteristic for each actual placement of the slave housing (second housing 201) when the placement of the master housing (first housing 101) is "Free."

[0102] Figure 7C is a graph showing an example of the difference between the second frequency characteristic and the second reference frequency characteristic for each actual placement of the slave housing (second housing 201) when the placement of the master housing (first housing 101) is "Shelf."

[0103] FIG. 7D is a graph showing an example of the difference between the second frequency characteristic and the second reference frequency characteristic for each actual placement of the slave housing (second housing 201) when the placement of the master housing (first housing 101) is “Wall.”

[0104] 7A to 7D, the arrangement of a master housing (first housing 101) and a slave housing (second housing 201) in space is shown as "SP." Also, "Shelf" indicates that the master housing (first housing 101) or the slave housing (second housing 201) is arranged on a bookshelf.

[0105] For example, in a space such as a room, a plurality of predetermined arrangements are assumed for the arrangement of housings in which speakers are provided, as shown in Figures 3A to 3D. For example, the comparison analysis unit 116 estimates the arrangement of the first housing 101 and the second housing 201 by estimating which of the plurality of predetermined arrangements as shown in Figures 3A to 3D the arrangement of the first housing 101 and the arrangement of the second housing 201 is closest to.

[0106] The second reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up a second reference test sound based on a test signal output from a second test speaker provided in a second test enclosure installed at a specific position in the test space, using a first test microphone provided in a first test enclosure.

[0107] The second test housing and the second test speaker are basically the same as the second housing 201 and the second speaker 230, and the second reference test sound is the same as the second test sound. When the second reference test sound is output from the second test speaker, the equalizer does not correct the test signal representing the second reference test sound. The second reference frequency characteristic is a frequency characteristic calculated from the sound signal picked up by the first test microphone when the second reference test sound is output from the second test speaker when the second test housing is in the standard "Free" arrangement (specifically, the average arrangement among the "Free" arrangements).

[0108] For example, the designer of the audio reproduction system 2 designs the entire audio reproduction system, including the speaker characteristics, so that the frequency characteristics of the audio signal are optimized in the standard "Free" arrangement, and then calculates the second reference frequency characteristic from the picked-up signal obtained by picking up a second reference test audio based on a test signal with a first test microphone provided in a first test housing. At this time, no correction is made by an equalizer, but the second reference audio with the optimal frequency characteristics is output from the second test speaker in the standard "Free" arrangement. Note that the first reference frequency characteristic is calculated in the same manner as in embodiment 1.

[0109] In the second embodiment, the first test housing and the second test housing are arranged in the "Free" arrangement shown in Fig. 3A. That is, the first reference frequency and the second reference frequency characteristics are calculated when the first test housing and the second test housing are arranged in the "Free" arrangement.

[0110] For example, the comparative analysis unit 116 calculates the difference in a predetermined frequency band (e.g., 50 Hz to 6 kHz) between a second reference frequency characteristic calculated in advance using a second test housing installed at a specific position in the test space and a second frequency characteristic calculated in the user's space. However, because the second collected sound signal representing the second test sound output from the second speaker 230 is collected by the first microphone 130 provided in the first housing 101, the second frequency characteristic of the second collected sound signal is affected by the arrangement of the first housing 101. Therefore, the difference between the second reference frequency characteristic and the second frequency characteristic varies depending on the arrangement of the first housing 101. Therefore, the comparative analysis unit 116 estimates the arrangement of the second housing 201 using the estimated result of the arrangement of the first housing 101 as described above.

[0111] Figure 7A shows the difference in a specified frequency band between the second reference frequency characteristic and the second frequency characteristic according to the arrangement of the second housing 201 ("Free," "Wall," "Corner," and "Shelf") when the arrangement of the first housing 101 in the user's space corresponds to "Corner" (arrangement close to "Corner").

[0112] Figure 7B shows the difference in a specified frequency band between the second reference frequency characteristic and the second frequency characteristic according to the arrangement of the second housing 201 ("Free," "Wall," "Corner," and "Shelf") when the arrangement of the first housing 101 in the user's space corresponds to "Free" (an arrangement close to "Free").

[0113] Figure 7C shows the difference in a specified frequency band between the second reference frequency characteristic and the second frequency characteristic according to the arrangement of the second housing 201 ("Free," "Wall," "Corner," and "Shelf") when the arrangement of the first housing 101 in the user's space corresponds to "Shelf" (arrangement close to "Shelf").

[0114] Figure 7D shows the difference in a specified frequency band between the second reference frequency characteristic and the second frequency characteristic according to the arrangement of the second housing 201 ("Free," "Wall," "Corner," and "Shelf") when the arrangement of the first housing 101 in the user's space corresponds to "Wall" (arrangement close to "Wall").

[0115] For example, the comparison and analysis unit 116 smoothes each of the second reference frequency characteristic and the second frequency characteristic using an octave band filter such as a ⅓ octave band filter, then normalizes the amplitude level at a signal level of 1 kHz and converts the amplitude level into decibel units. Normalizing the amplitude level makes it possible to appropriately compare the second reference frequency characteristic and the second frequency characteristic even if there is a difference in the sound pickup levels between the second reference frequency characteristic and the second frequency characteristic.

[0116] For example, the comparison / analysis unit 116 adds up the absolute values ​​of the differences between the second reference frequency characteristic and the second frequency characteristic for each frequency in a predetermined frequency band, and determines whether the sum falls within any of the numerical ranges set for each of a plurality of predetermined layouts (e.g., a "Free" layout, a "Wall" layout, a "Corner" layout, and a "Shelf" layout) and according to the layout of the first housing 101, thereby estimating the layout of the second housing 201. For example, when the layout of the first housing 101 is "Corner," the comparison / analysis unit 116 determines whether the sum falls within any of the numerical ranges set for each of the plurality of predetermined layouts for the first housing 101 when the layout is "Corner." For example, when four predetermined layouts are assumed for the layout of the first housing 101 and the layout of the second housing 201, four numerical ranges are set for each of the layouts of the first housing 101, resulting in a total of 16 numerical ranges being set.

[0117] For example, when the position of the first housing 101 is "Corner", a numerical range A is set for determining the position of the second housing 201 as "Free", a numerical range B is set for determining the position of the second housing 201 as "Wall", a numerical range C is set for determining the position of the second housing 201 as "Corner", and a numerical range D is set for determining the position of the second housing 201 as "Shelf".

[0118] For example, when the position of the first housing 101 is "Free", a numerical range E is set for determining the position of the second housing 201 as "Free", a numerical range F is set for determining the position of the second housing 201 as "Wall", a numerical range G is set for determining the position of the second housing 201 as "Corner", and a numerical range H is set for determining the position of the second housing 201 as "Shelf".

[0119] For example, when the position of the first housing 101 is "Shelf", a numerical range I for determining the position of the second housing 201 as "Free", a numerical range J for determining the position of the second housing 201 as "Wall", a numerical range K for determining the position of the second housing 201 as "Corner", and a numerical range L for determining the position of the second housing 201 as "Shelf" are set.

[0120] For example, when the position of the first housing 101 is "Wall", a numerical range M is set for determining the position of the second housing 201 as "Free", a numerical range N is set for determining the position of the second housing 201 as "Wall", a numerical range O is set for determining the position of the second housing 201 as "Corner", and a numerical range P is set for determining the position of the second housing 201 as "Shelf".

[0121] The numerical ranges A to D do not overlap when the first housing 101 is positioned at "Corner." Similarly, the numerical ranges E to H do not overlap when the first housing 101 is positioned at "Free," the numerical ranges I to L do not overlap when the first housing 101 is positioned at "Shelf," and the numerical ranges M to P do not overlap when the first housing 101 is positioned at "Wall." For example, when the first housing 101 is positioned at "Corner," if the added value falls within numerical range A, it can be estimated that the second housing 201 is positioned at "Free."

[0122] The comparison result between the second reference frequency characteristic and the second frequency characteristic changes according to changes in the arrangement of second housing 201. In other words, there is a correlation between the comparison result between the second reference frequency characteristic and the second frequency characteristic and the arrangement of second housing 201. Therefore, by comparing the second reference frequency characteristic with the second frequency characteristic, it is possible to easily estimate the arrangement of second housing 201.

[0123] As described above, in the second embodiment, the arrangement of the first housing 101 is estimated, and the second frequency characteristic of the second collected sound signal indicating the second test sound output from the second speaker 230 of the second housing 201 and collected by the first microphone 130 is calculated. Next, the difference between the second reference frequency characteristic and the second frequency characteristic is calculated, and the calculated difference is quantified. Then, the arrangement of the second housing 201 is estimated depending on which of the numerical ranges set for each of the plurality of predetermined arrangements the calculated numerical value falls within. Note that, as described above, the numerical ranges set for each of the plurality of predetermined arrangements are prepared in advance for each arrangement of the first housing 101.

[0124] Returning to the description of FIG. 2 , the determination unit 117 determines, as the first correction parameter, a correction parameter that is predetermined for a predetermined arrangement that is estimated as the arrangement of the first housing 101 from among a plurality of predetermined arrangements (e.g., a “Free” arrangement, a “Wall” arrangement, a “Corner” arrangement, and a “Shelf” arrangement). The determination unit 117 also determines, as the second correction parameter, a correction parameter that is predetermined for a predetermined arrangement that is estimated as the arrangement of the second housing 201 from among the plurality of predetermined arrangements. As shown in FIG. 2 , the memory 180 stores a group of correction parameters that are predetermined for a plurality of predetermined arrangements. For example, a correction parameter that is predetermined for the “Free” arrangement, a correction parameter that is predetermined for the “Wall” arrangement, a correction parameter that is predetermined for the “Corner” arrangement, and a correction parameter that is predetermined for the “Shelf” arrangement are stored in the memory 180.

[0125] The designer of the audio reproduction system 2 can determine in advance optimal correction parameters for each of a plurality of predetermined layouts by conducting experiments, simulations, or the like. Therefore, by using the correction parameters predetermined for the predetermined layouts estimated as the layout of the first housing 101 as the first correction parameters, the first correction parameters can be easily determined. Furthermore, by using the correction parameters predetermined for the predetermined layouts estimated as the layout of the second housing 201 as the second correction parameters, the second correction parameters can be easily determined. For example, if the arrangement of the first housing 101 is estimated to be the "Corner" arrangement among a plurality of predetermined arrangements (specifically, an arrangement close to the "Corner" arrangement), and the arrangement of the second housing 201 is estimated to be the "Free" arrangement among a plurality of predetermined arrangements (specifically, an arrangement close to the "Free" arrangement), the correction parameter from the correction parameter group that is predetermined for the "Corner" arrangement can be used as the first correction parameter, and the correction parameter from the correction parameter group that is predetermined for the "Free" arrangement can be used as the second correction parameter.

[0126] Note that, in order to determine the first correction parameter and the second correction parameter, the first frequency characteristic used in estimating the arrangement of the first housing 101 and the second frequency characteristic used in estimating the arrangement of the second housing 201 may be used. This will be described with reference to Fig. 5. Fig. 5 is a block diagram showing another example of the correction parameter generator 114 according to the first embodiment, but in the description of the second embodiment, the correction parameter generator 114 shown in Fig. 5 is replaced with a correction parameter generator 114a.

[0127] The correction parameter generator 114a differs from the correction parameter generator 114a described using Fig. 2 in that it includes a determination unit 117a instead of the determination unit 117, and that the memory 180 does not store a correction parameter group. Since the other points are the same as the correction parameter generator 114a described using Fig. 2, a description thereof will be omitted.

[0128] No correction parameter group is stored in the memory 180. That is, the determination unit 117a determines the first and second correction parameters without using a correction parameter group.

[0129] The determination unit 117a determines the first correction parameter in the same manner as in Embodiment 1. Furthermore, the determination unit 117a determines the second correction parameter that reduces the difference between the second reference frequency characteristic and the second frequency characteristic in a predetermined frequency range for a predetermined arrangement that is estimated as the arrangement of the second housing 201 from among a plurality of predetermined arrangements.

[0130] For example, the first reference frequency characteristic is the frequency characteristic of the first reference test sound based on the test signal, calculated in a state where the entire audio reproduction system, including speaker characteristics, is designed so that the frequency characteristics of the audio signal are optimized in a standard "Free" arrangement. Also, for example, the second reference frequency characteristic is the frequency characteristic of the second reference test sound based on the test signal, calculated in a state where the entire audio reproduction system, including speaker characteristics, is designed so that the frequency characteristics of the audio signal are optimized in a standard "Free" arrangement.

[0131] Therefore, by determining a first correction parameter that reduces the difference between the first frequency characteristic and the first reference frequency characteristic in a specified frequency band, and determining a second correction parameter that reduces the difference between the second frequency characteristic and the second reference frequency characteristic in a specified frequency band, it is possible to improve the frequency characteristics of the audio signal even at the listening position in the user's space.

[0132] However, the first reference frequency characteristic is a frequency characteristic calculated when the first test housing is in a specific position (the "Free" position), and the position of the first test housing may differ from the position of first housing 101. Furthermore, the second reference frequency characteristic is a frequency characteristic calculated when the second test housing is in a specific position (the "Free" position), and the position of the second test housing may differ from the position of second housing 201. Therefore, the frequency range in which the first reference frequency characteristic should be compared with the first frequency characteristic and the frequency range in which the second reference frequency characteristic should be compared with the second frequency characteristic will differ depending on the positions of first housing 101 and second housing 201.

[0133] In response to this, the designer can determine in advance, for each of a plurality of predetermined arrangements, the frequency range in which the first reference frequency characteristic should be compared with the first frequency characteristic and the frequency range in which the second reference frequency characteristic should be compared with the second frequency characteristic, by performing an experiment, a simulation, etc. Therefore, it is possible to determine the first correction parameter and the second correction parameter according to the arrangement of the first housing 101 and the second housing 201.

[0134] As described above, the first microphone 130 required to determine the second correction parameter for the second speaker 230 provided in the second housing 201 is pre-installed in the first housing 101. This eliminates the need for the user to separately prepare special equipment, such as a microphone, in addition to that required for normal playback. Furthermore, the location of the second housing 201 is automatically estimated from the second frequency characteristics of the second collected signal indicating the second test audio collected by the first microphone 130, and the second correction parameter is automatically determined from the estimated location of the second housing. This eliminates the need for the user to have the skills and expertise to collect audio signals at the listening position and determine the correction parameters. Therefore, even if the audio playback system 2 includes multiple speakers and only one microphone in a single housing, a user without specialized knowledge can automatically improve the frequency characteristics at the listening position with a single touch, thereby easily achieving the performance intended by the designer.

[0135] Third Embodiment Next, an audio reproduction system according to a third embodiment will be described with reference to FIG.

[0136] FIG. 8 is a diagram showing an example of the configuration of an audio reproduction system 3 according to the third embodiment.

[0137] The audio reproduction system 3 is a system for outputting audio based on an input audio signal input to the audio reproduction system 3 from a sound source player connected to the input terminal 140, from a first speaker 160 and a second speaker 230. The sound source player may be built into the audio reproduction system 3. That is, the sound source player may be externally attached to the audio reproduction system 3 as a component outside the audio reproduction system 3, or may be built into the audio reproduction system 3 as a component of the audio reproduction system 3. The audio reproduction system 3 has a function for optimizing the frequency characteristics of the audio signal at the listening position, and this function will be described below.

[0138] The audio playback system 3 includes a first housing 102, a processor 110b, an equalizer 120a, a first microphone 130, an input terminal 140, an amplifier 150, a first speaker 160, and a first communication I / F (interface) 170a, as well as a second housing 202, a second communication I / F 210a, an amplifier 220, a second speaker 230, and a second microphone 240.

[0139] Hereinafter, explanations of components with the same reference numerals and terms with the same names as those in the first or second embodiment may be omitted.

[0140] The audio reproduction system 3 is a computer including a processor 110b (microprocessor), a memory 180, a communication interface, etc. The audio reproduction system 3 may also include a user interface. As shown in Fig. 8 , the processor 110b includes a test signal generator 111a, a signal switcher 112, a sound pickup measurement device 113b, and a correction parameter generator 114b. In other words, these components are realized by the processor 110b executing a program stored in the memory 180, etc.

[0141] For example, memory 180 stores data related to processing such as reference frequency characteristics, system information, or correction parameter groups, as in the first embodiment, except that the reference frequency characteristics stored therein include a first reference frequency characteristic and a fourth reference frequency characteristic for first housing 102, and a second reference frequency characteristic and a third reference frequency characteristic for second housing 202.

[0142] For example, the audio reproduction system 3 can reproduce stereo audio by operating the first housing 102, in which the processor 110b is provided, as a master housing and the second housing 202 as a slave housing. The audio reproduction system 3 may further include another slave housing and may reproduce surround audio. Furthermore, the master housing and the slave housing may be arranged in a single housing, so that the audio reproduction system 3 becomes a device in a single housing.

[0143] The first housing 102 is a component corresponding to the first housing 100 of the first embodiment and the first housing 101 of the second embodiment, and a description that overlaps with the first and second embodiments will be omitted.

[0144] Second housing 202 is installed in the space where first housing 102 is installed. Second speaker 230 is provided in second housing 202. Second microphone 240 is provided in second housing 202. In other words, second housing 202 is provided with not only a speaker but also a microphone.

[0145] The first communication I / F 170a is a communication interface that is provided in the first housing 102 and is capable of transmitting an audio signal. The first communication I / F 170a transmits the audio signal to the second communication I / F 210a of the second housing 202.

[0146] The second communication I / F 210a is provided in the second housing 202 and is capable of receiving an audio signal from the first communication I / F 170a. The second communication I / F 210a also transmits a picked-up signal collected by the second microphone 240 to the first communication I / F 170a of the first housing 102. The first communication I / F 170 and the second communication I / F 210 may be connected wirelessly or by wire.

[0147] The test signal generator 111 a, the signal switch 112, the sound collection measurement device 113 b, and the correction parameter generator 114 b are realized by the processor 110 b that executes a program stored in the memory 180.

[0148] In a mode for optimizing the frequency characteristics of the audio signal at the listening position, the equalizer 120a does not perform correction. In other words, the test signal generated by the test signal generator 111a is not corrected by the equalizer 120a. The processor 110b causes the first speaker 160 to output a first test sound based on the test signal generated by the test signal generator 111a. As a result, the first test sound is output from the first speaker 160 into the space in which the first housing 102 and the second housing 202 are installed. In addition, the test signal generator 111a causes the first communication I / F 170a to transmit a test signal to the second communication I / F 210a, thereby outputting a second test sound based on the test signal from the second speaker 230. As a result, the second test sound is output from the second speaker 230 into the space in which the first housing 102 and the second housing 202 are installed.

[0149] The first test sound output from first speaker 160 into the space in which first housing 102 and second housing 202 are installed is picked up by first microphone 130 provided in first housing 102 and second microphone 240 provided in second housing 202. For example, first microphone 130 picks up, as the first test sound, a direct sound from first speaker 160 and a reflected sound of the sound output from first speaker 160 reflected by walls or the like in the space in which first housing 102 and second housing 202 are installed. Furthermore, for example, second microphone 240 picks up, as the first test sound, a reflected sound of the sound output from first speaker 160 reflected by walls or the like in the space in which first housing 102 and second housing 202 are installed.

[0150] The second test sound output from the second speaker 230 into the space in which the first housing 102 and the second housing 202 are installed is picked up by the first microphone 130 provided in the first housing 102 and the second microphone 240 provided in the second housing 202. For example, the first microphone 130 picks up, as the second test sound, a sound that is a reflection of the sound output from the second speaker 230 by a wall or the like in the space in which the first housing 102 and the second housing 202 are installed. Furthermore, for example, the second microphone 240 picks up, as the second test sound, a direct sound from the second speaker 230 and a reflection of the sound output from the second speaker 230 by a wall or the like in the space in which the first housing 102 and the second housing 202 are installed.

[0151] The period during which the first test sound is output from the first speaker 160 does not overlap with the period during which the second test sound is output from the second speaker 230. If these periods overlap, the first microphone 130 will pick up the first test sound and the second test sound at the same time, and the second microphone 240 will pick up the first test sound and the second test sound at the same time, making it difficult to distinguish between the first test sound and the second test sound.

[0152] The sound collection measurement device 113b acquires a first collected sound signal indicating the first test sound collected by the first microphone 130. The sound collection measurement device 113b also acquires a second collected sound signal indicating the second test sound collected by the first microphone 130. The third collected sound signal indicating the second test sound collected by the second microphone 240 is transmitted from the second communication I / F 210a to the first communication I / F 170a, and the sound collection measurement device 113b acquires the third collected sound signal indicating the second test sound collected by the second microphone 240. The fourth collected sound signal indicating the first test sound collected by the second microphone 240 is transmitted from the second communication I / F 210a to the first communication I / F 170a, and the sound collection measurement device 113b acquires the fourth collected sound signal indicating the first test sound collected by the second microphone 240. That is, the sound collection measurement device 113b acquires the sound from the first microphone 130 and the sound from the second microphone 240 transmitted via the second communication I / F 210a and the first communication I / F 170a.

[0153] The sound picked up by second microphone 240 at the timing when second speaker 230 outputs second test sound is sound that includes direct sound that reaches second microphone 240 directly and reflected sound that reaches second microphone 240 after being reflected by a wall or the like, and although it is different from the second test sound output by second speaker 230, this sound is also referred to as second test sound for convenience. Also, for convenience, the sound picked up by second microphone 240 based on the sound referred to as second test sound is referred to as third picked-up signal.

[0154] Furthermore, the sound picked up by second microphone 240 at the timing when first test sound is output from first speaker 160 is sound that includes, of the first test sound, direct sound that reaches second microphone 240 directly and reflected sound that reaches second microphone 240 after being reflected by a wall or the like, and although it is different from the first test sound output by first speaker 160, this sound is also referred to as the first test sound for convenience. Furthermore, for convenience, the sound picked up by second microphone 240 based on the sound that is referred to as the first test sound is referred to as the fourth picked-up signal.

[0155] The sound collection measurement device 113b outputs the acquired first, second, third, and fourth collected sound signals to the correction parameter generator 114b.

[0156] The correction parameter generator 114b calculates a first frequency characteristic of the first collected sound signal, estimates the arrangement of the first housing 102 in space based on the calculated first frequency characteristic, and determines a first correction parameter based on the estimated arrangement of the first housing 102. The correction parameter generator 114b also calculates a third frequency characteristic of the third collected sound signal, estimates the arrangement of the second housing 202 in space based on the calculated third frequency characteristic, and determines a second correction parameter based on the estimated arrangement of the second housing 202. Details of the correction parameter generator 114b will be described later. The correction parameter generator 114b sets the determined first and second correction parameters in the equalizer 120a.

[0157] Thereafter, in a mode for reproducing normal audio, the equalizer 120a corrects the frequency characteristics of an input audio signal input to the audio reproduction system 3 using the first correction parameter to generate a first corrected audio signal, and outputs audio based on the first corrected audio signal to the first speaker 160. The equalizer 120a also corrects the frequency characteristics of an input audio signal input to the audio reproduction system 3 using the second correction parameter to generate a second corrected audio signal, and outputs the audio based on the second corrected audio signal to the second speaker 230 via the first communication I / F 170a. In other words, audio based on the first corrected audio signal generated by correcting the frequency characteristics of the input audio signal using the first correction parameter is output from the first speaker 160, and audio based on the second corrected audio signal generated by correcting the frequency characteristics of the input audio signal using the second correction parameter is output from the second speaker 230, allowing the user to hear audio with improved frequency characteristics at the listening position.

[0158] Next, details of the correction parameter generator 114b will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of the correction parameter generator 114 according to the first embodiment, but in the description of the third embodiment, the correction parameter generator 114 shown in Fig. 2 is replaced with a correction parameter generator 114b.

[0159] The correction parameter generator 114b includes a frequency characteristic analysis unit 115, a comparison analysis unit 116, and a determination unit 117. The frequency characteristic analysis unit 115, the comparison analysis unit 116, and the determination unit 117 are realized by the processor 110b that executes a program stored in the memory 180, or the like.

[0160] The correction parameter generator 114b uses the first reference frequency characteristic or the fourth reference frequency characteristic for the first housing 102, and the second reference frequency characteristic or the third reference frequency characteristic for the second housing 202, stored in the memory 180, to estimate the arrangement of the first housing 102 and the second housing 202, and to determine the first correction parameter and the second correction parameter.

[0161] The third reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up a second reference test sound based on a test signal output from a second test speaker provided in a second test enclosure installed at a specific position in the test space, using a second test microphone provided in the second test enclosure.

[0162] The second test microphone is basically the same as the second microphone 240. The third reference frequency characteristic is a frequency characteristic calculated from the sound signal picked up by the second test microphone when the second reference test sound is output from the second test speaker when the second test housing is in the standard "Free" arrangement (specifically, the average arrangement among the "Free" arrangements).

[0163] The fourth reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up a first reference test sound based on a test signal output from a first test speaker provided in a first test enclosure installed at a specific position in the test space, using a second test microphone provided in a second test enclosure.

[0164] The fourth reference frequency characteristic is a frequency characteristic calculated from the sound signal picked up by the second test microphone when the first reference test audio is output from the first test speaker when the first test housing is in the standard "Free" arrangement (specifically, the average arrangement among the "Free" arrangements).

[0165] For example, the designer of the audio reproduction system 3 may design the entire audio reproduction system, including the speaker characteristics, so that the frequency characteristics of the audio signal are optimized in the standard "Free" arrangement, and then calculate a third reference frequency characteristic from a picked-up signal obtained by collecting a second reference test sound based on a test signal with a second test microphone provided in a second test housing. At this time, the second reference sound with the optimal frequency characteristics is output from the second test speaker in the standard "Free" arrangement, without being corrected by an equalizer. Furthermore, the designer of the audio reproduction system 3 may design the entire audio reproduction system as described above, and then calculate a fourth reference frequency characteristic from a picked-up signal obtained by collecting a first reference test sound based on a test signal with a second test microphone provided in a second test housing. At this time, the first reference sound with the optimal frequency characteristics is output from the first test speaker in the standard "Free" arrangement, without being corrected by an equalizer. The first and second reference frequency characteristics are calculated in the same manner as in the first and second embodiments.

[0166] In the third embodiment, the first test housing and the second test housing are arranged in the "Free" arrangement shown in Fig. 3A. That is, the first reference frequency, the second reference frequency characteristic, the third reference frequency characteristic, and the fourth reference frequency characteristic are calculated when the first test housing and the second test housing are arranged in the "Free" arrangement.

[0167] The frequency characteristic analysis unit 115 calculates a first frequency characteristic of a first collected signal output from the first speaker 160 and indicating the first test sound picked up by the first microphone 130, a second frequency characteristic of a second collected signal output from the second speaker 230 and indicating the second test sound picked up by the first microphone 130, a third frequency characteristic of a third collected signal output from the second speaker 230 and indicating the second test sound picked up by the second microphone 240, and a fourth frequency characteristic of a fourth collected signal output from the first speaker 160 and indicating the first test sound picked up by the second microphone 240. For example, the frequency characteristic analysis unit 115 performs an FFT on the first collected signal to calculate a first frequency characteristic of the first collected signal, performs an FFT on the second collected signal to calculate a second frequency characteristic of the second collected signal, performs an FFT on the third collected signal to calculate a third frequency characteristic of the third collected signal, and performs an FFT on the fourth collected signal to calculate a fourth frequency characteristic of the fourth collected signal.

[0168] The comparison and analysis unit 116 estimates the location of the first housing 102 by comparing the first frequency characteristic with the first reference frequency characteristic stored in the memory 180, and estimates the location of the second housing 202 by comparing the third frequency characteristic with the third reference frequency characteristic stored in the memory 180. When estimating the locations of the first housing 102 and the second housing 202, the comparison and analysis unit 116 may use system information including information on the frequency characteristics of the first microphone 130 and the second microphone 240. The method for estimating the location of the first housing 102 is the same as that described in the first embodiment, and therefore a description thereof will be omitted. The method for estimating the location of the second housing 202 is also basically the same as the method for estimating the location of the first housing 102, and therefore a description thereof will be omitted. In the second embodiment, no microphone is provided in the second housing 201, and the position of the first housing 101 is estimated using the first microphone 130 provided in the first housing 101, and the method for estimating the position of the first housing 101 is different from the method for estimating the position of the second housing 201. However, in the third embodiment, a second microphone 240 is provided in the second housing 202 as in the first housing 102, and the position of the second housing 202 can be estimated using the second speaker 230 and second microphone 240 provided in the second housing 202 in the same way as the position of the first housing 102 is estimated using the first speaker 160 and first microphone 130 provided in the first housing 102.

[0169] The determination unit 117 determines, as the first correction parameter, a correction parameter that is predetermined for a predetermined arrangement that is estimated as the arrangement of the first housing 102 from among a plurality of predetermined arrangements (e.g., a "Free" arrangement, a "Wall" arrangement, a "Corner" arrangement, and a "Shelf" arrangement). The determination unit 117 also determines, as the second correction parameter, a correction parameter that is predetermined for a predetermined arrangement that is estimated as the arrangement of the second housing 202 from among the plurality of predetermined arrangements. As shown in FIG. 2 , the memory 180 stores a group of correction parameters that are predetermined for a plurality of predetermined arrangements. For example, a correction parameter that is predetermined for the "Free" arrangement, a correction parameter that is predetermined for the "Wall" arrangement, a correction parameter that is predetermined for the "Corner" arrangement, and a correction parameter that is predetermined for the "Shelf" arrangement are stored in the memory 180.

[0170] The designer of the audio reproduction system 3 can determine in advance optimal correction parameters for each of a plurality of predetermined layouts by conducting experiments, simulations, or the like. Therefore, by directly using the correction parameters predetermined for the predetermined layouts estimated as the layout of the first housing 102 as the first correction parameters, the first correction parameters can be easily determined. Furthermore, by directly using the correction parameters predetermined for the predetermined layouts estimated as the layout of the second housing 202 as the second correction parameters, the second correction parameters can be easily determined. For example, if the arrangement of the first housing 102 is estimated to be the "Corner" arrangement among a plurality of predetermined arrangements (specifically, an arrangement close to the "Corner" arrangement), and the arrangement of the second housing 202 is estimated to be the "Free" arrangement among a plurality of predetermined arrangements (specifically, an arrangement close to the "Free" arrangement), the correction parameter from the correction parameter group that is predetermined for the "Corner" arrangement can be used as the first correction parameter, and the correction parameter from the correction parameter group that is predetermined for the "Free" arrangement can be used as the second correction parameter.

[0171] Note that, to determine the first correction parameter and the second correction parameter, the first frequency characteristic used in estimating the arrangement of the first housing 102 and the third frequency characteristic used in estimating the arrangement of the second housing 202 may be used, as well as the second frequency characteristic of a second collected sound signal indicating the second test sound output from the second speaker 230 and picked up by the first microphone 130, and the fourth frequency characteristic of a fourth collected sound signal indicating the first test sound output from the first speaker 160 and picked up by the second microphone 240. This will be described with reference to FIG. 5 . FIG. 5 is a block diagram showing another example of the correction parameter generator 114 according to the first embodiment. However, in the description of the third embodiment, the correction parameter generator 114 shown in FIG. 5 is replaced with a correction parameter generator 114b.

[0172] The correction parameter generator 114b differs from the correction parameter generator 114b described using Fig. 2 in that it includes a determination unit 117a instead of the determination unit 117, and that the memory 180 does not store a correction parameter group. Since the other points are the same as the correction parameter generator 114b described using Fig. 2, a description thereof will be omitted.

[0173] No correction parameter group is stored in the memory 180. That is, the determination unit 117a determines the first and second correction parameters without using a correction parameter group.

[0174] The determination unit 117a determines, for each predetermined frequency range for a predetermined arrangement estimated as the arrangement of the first housing 102 from among a plurality of predetermined arrangements, a first correction parameter that reduces the difference between the first reference frequency characteristic and the first frequency characteristic, or the difference between the fourth reference frequency characteristic and the fourth frequency characteristic, which are predetermined for the predetermined arrangement estimated as the arrangement of the first housing 102.

[0175] In addition, the determination unit 117a determines, for each predetermined frequency range for a predetermined arrangement estimated as the arrangement of the second housing 202 from among a plurality of predetermined arrangements, a second correction parameter that reduces the difference between the second reference frequency characteristic and the second frequency characteristic, or the difference between the third reference frequency characteristic and the third frequency characteristic, which are predetermined for the predetermined arrangement estimated as the arrangement of the second housing 202.

[0176] For example, the first reference frequency characteristic is the frequency characteristic of the first reference test sound based on the test signal, calculated in a state where the entire audio reproduction system, including speaker characteristics, is designed so that the frequency characteristics of the audio signal are optimized in a standard "Free" arrangement. Furthermore, for example, the third reference frequency characteristic is the frequency characteristic of the second reference test sound based on the test signal, calculated in a state where the entire audio reproduction system, including speaker characteristics, is designed so that the frequency characteristics of the audio signal are optimized in a standard "Free" arrangement.

[0177] Therefore, by determining a first correction parameter that reduces the difference between the first frequency characteristic and the first reference frequency characteristic in a specified frequency band, and determining a second correction parameter that reduces the difference between the third frequency characteristic and the third reference frequency characteristic in a specified frequency band, it is possible to improve the frequency characteristics of the audio signal even at the listening position in the user's space.

[0178] However, the first reference frequency characteristic is a frequency characteristic calculated when the first test housing is in a specific position (the "Free" position), and the position of the first test housing may differ from the position of first housing 102. Furthermore, the third reference frequency characteristic is a frequency characteristic calculated when the second test housing is in a specific position (the "Free" position), and the position of the second test housing may differ from the position of second housing 201. Therefore, the frequency range in which the first reference frequency characteristic should be compared with the first frequency characteristic differs depending on the position of first housing 102, and the frequency range in which the third reference frequency characteristic should be compared with the third frequency characteristic differs depending on the position of second housing 202. Furthermore, since it is possible to calculate the second frequency characteristic of the second collected sound signal indicating the second test sound of the second speaker 230 collected by the first microphone 130 and the fourth frequency characteristic of the fourth collected sound signal indicating the first test sound of the first speaker 160 collected by the second microphone 240, there may be a frequency range in which it is better to compare the fourth reference frequency characteristic with the fourth frequency characteristic, depending on the arrangement of the first housing 102. Furthermore, there may be a frequency range in which it is better to compare the second reference frequency characteristic with the second frequency characteristic, depending on the arrangement of the second housing 202.

[0179] In response to this, the designer can determine in advance, by conducting experiments, simulations, or the like, the frequency range in which the first reference frequency characteristic, the second reference frequency characteristic, the third reference frequency characteristic, or the fourth reference frequency characteristic should be compared with the first frequency characteristic, the second frequency characteristic, the third frequency characteristic, or the fourth frequency characteristic for each of a plurality of predetermined arrangements. For example, the designer can determine in advance, by conducting experiments, simulations, or the like, that when the arrangement of the first housing 102 is "corner," it is better to compare the first reference frequency characteristic with the first frequency characteristic from a Hz to b Hz in a predetermined frequency band, and to compare the fourth reference frequency characteristic with the fourth frequency characteristic from b Hz to c Hz. Furthermore, for example, the designer can determine in advance, by conducting experiments, simulations, or the like, that when the arrangement of the second housing 202 is "shelf," it is better to compare the third reference frequency characteristic with the third frequency characteristic from d Hz to e Hz in a predetermined frequency band, and to compare the second reference frequency characteristic with the second frequency characteristic from e Hz to f Hz. Therefore, the first correction parameter and the second correction parameter can be determined according to the arrangement of the first housing 102 and the second housing 202.

[0180] As described above, the second microphone 240 required to determine the second correction parameter for the second speaker 230 provided in the second housing 202 is pre-installed in the second housing 202. This eliminates the need for the user to separately prepare special equipment, such as a microphone, in addition to that required for normal playback. Furthermore, the location of the second housing 202 is automatically estimated from the third frequency characteristic of the third collected signal representing the second test audio picked up by the second microphone 240, and the second correction parameter is automatically determined from the estimated location of the second housing 202. This eliminates the need for the user to have the skills and expertise to collect audio signals at the listening position and determine the correction parameter. Therefore, even if the audio playback system 3 includes multiple speakers and multiple microphones, a user without specialized knowledge can automatically improve the frequency characteristic at the listening position with a single touch, thereby easily achieving the performance intended by the designer.

[0181] (Other Embodiments) As described above, the embodiments have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. Furthermore, it is also possible to combine the components described in the above embodiments to create new embodiments.

[0182] For example, the equalizer described in the above embodiment may be a graphic equalizer.

[0183] For example, the equalizer described in the above embodiment is an equalizer that performs corrections resulting from speaker placement, but the audio playback system may also have an equalizer separate from the equalizer that performs corrections at the time of design (e.g., before a user purchases) to make the speaker characteristics match the designer's intentions.

[0184] For example, the arrangement of the first test housing and the second test housing described in the above embodiment is the "Free" arrangement shown in Fig. 3A, but the arrangement of the first test housing and the second test housing may be the "Wall" arrangement shown in Fig. 3B, the "Corner" arrangement shown in Fig. 3C, or the "Shelf" arrangement shown in Fig. 3D. Furthermore, the reference frequency characteristics may be calculated when the test housing is in an arrangement other than the "Free" arrangement (for example, the "Wall" arrangement, the "Corner" arrangement, or the "Shelf" arrangement).

[0185] For example, in the above embodiment, an example has been described in which the reference frequency characteristics are frequency characteristics calculated in advance when the test housing is placed in a specific position, but this is not limited to this. For example, the reference frequency characteristics may be calculated in advance when the test housing is placed in each of a plurality of predetermined positions (e.g., a "free" position, a "wall" position, a "corner" position, and a "shelf" position). In other words, the reference frequency characteristics for the "free" position, the reference frequency characteristics for the "wall" position, the reference frequency characteristics for the "corner" position, and the reference frequency characteristics for the "shelf" position may each be calculated in advance.

[0186] As a result, the predetermined arrangement corresponding to the reference frequency characteristic that has the smallest difference from the frequency characteristic of the picked-up signal representing the test sound among the calculated reference frequency characteristics can be estimated as the arrangement of the first or second housing. For example, if the difference between the first frequency characteristic and the reference frequency characteristic for the "Wall" arrangement is the smallest, it can be estimated that the arrangement of the first housing is "Wall." Furthermore, by determining the first correction parameter or the second correction parameter using the reference frequency characteristic corresponding to the estimated arrangement of the first or second housing, the first correction parameter or the second correction parameter can be determined with higher accuracy.

[0187] For example, the present disclosure can be realized not only as an audio reproduction system, but also as an audio reproduction method including steps (processing) performed by components that make up the audio reproduction system.

[0188] FIG. 9 is a flowchart showing an example of an audio reproducing method according to another embodiment.

[0189] The audio reproduction method is an audio reproduction method executed by an audio reproduction system, which includes a first housing installed in a space, a first speaker provided in the first housing, and a first microphone provided in the first housing. As shown in FIG. 9, the audio reproduction method outputs a first test audio based on a test signal to the first speaker (step S11), obtains a first picked-up signal indicating the first test audio picked up by the first microphone (step S12), calculates a first frequency characteristic of the first picked-up signal (step S13), estimates the position of the first housing in the space based on the first frequency characteristic (step S14), determines a first correction parameter based on the position of the first housing (step S15), corrects the frequency characteristic of an input audio signal input to the audio reproduction system using the first correction parameter to generate a first corrected audio signal (step S16), and outputs audio based on the first corrected audio signal to the first speaker (step S17).

[0190] For example, the present disclosure can be realized as a program for causing a computer (processor) to execute steps included in an audio playback method. Furthermore, the present disclosure can be realized as a non-transitory computer-readable recording medium, such as a CD-ROM, on which the program is recorded.

[0191] For example, when the present disclosure is realized as a program (software), each step is performed by running the program using hardware resources such as a computer's CPU, memory, input / output circuits, etc. In other words, each step is performed by the CPU acquiring data from memory or input / output circuits, etc., performing calculations, and outputting the calculation results to memory or input / output circuits, etc.

[0192] In the above-described embodiment, each component included in the audio reproduction system may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0193] Some or all of the functions of the audio playback system according to the above-described embodiments are typically realized as an LSI, which is an integrated circuit. These may be implemented individually on a single chip, or some or all of them may be integrated into a single chip. Furthermore, the integrated circuit is not limited to an LSI, and may be realized using a dedicated circuit or a general-purpose processor. It is also possible to use an FPGA (Field Programmable Gate Array), which can be programmed after LSI manufacture, or a reconfigurable processor, which allows the connections and settings of circuit cells within an LSI to be reconfigured.

[0194] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, that technology may naturally be used to integrate each component included in the audio playback system into an integrated circuit.

[0195] In addition, this disclosure also includes forms obtained by making various modifications to the embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions in each embodiment within the scope of the present disclosure.

[0196] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0197] (Technology 1) An audio reproduction system comprising: a first housing installed in a space; a first speaker provided in the first housing; a first microphone provided in the first housing; a processor; and an equalizer unit, wherein the processor causes the first speaker to output a first test sound based on a test signal, acquires a first picked-up signal indicating the first test sound picked up by the first microphone, calculates a first frequency characteristic of the first picked-up signal, estimates the position of the first housing in the space based on the first frequency characteristic, and determines a first correction parameter based on the position of the first housing, the equalizer unit corrects the frequency characteristic of an input audio signal input to the audio reproduction system using the first correction parameter to generate a first corrected audio signal, and the first speaker outputs audio based on the first corrected audio signal.

[0198] According to this, the first microphone required to determine the first correction parameter for the first speaker provided in the first housing is pre-installed in the first housing, so the user does not need to separately prepare special equipment such as a microphone in addition to what is necessary for normal playback. Furthermore, the location of the first housing is automatically estimated from the first frequency characteristic of the first collected signal indicating the first test sound picked up by the first microphone, and the first correction parameter is automatically determined from the estimated location of the first housing. This eliminates the need for the user to have the skills and expertise to collect an audio signal at the listening position and determine the correction parameter. Therefore, even a user without specialized knowledge can automatically improve the frequency characteristic at the listening position with a single touch, easily achieving the performance intended by the designer.

[0199] (Technology 2) An audio playback system described in Technology 1, wherein the processor estimates the placement of the first housing by comparing a first reference frequency characteristic for the first housing with the first frequency characteristic.

[0200] According to this, the comparison result between the first reference frequency characteristic and the first frequency characteristic changes according to the change in the arrangement of the first housing. In other words, there is a correlation between the comparison result between the first reference frequency characteristic and the first frequency characteristic and the arrangement of the first housing. Therefore, by comparing the first reference frequency characteristic and the first frequency characteristic, it is possible to easily estimate the arrangement of the first housing.

[0201] (Technology 3) An audio playback system described in Technology 1 or 2, in which the processor determines, as the first correction parameter, a predetermined correction parameter for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements.

[0202] This allows the designer to determine in advance optimal correction parameters for each of a plurality of predetermined layouts by conducting experiments, simulations, etc. Therefore, the first correction parameters can be easily determined by using the correction parameters determined in advance for the predetermined layouts estimated as the layout of the first housing as the first correction parameters.

[0203] (Technology 4) The audio reproduction system described in Technology 2, wherein the processor uses the first reference frequency characteristic to estimate the placement of the first housing and determine the first correction parameter.

[0204] According to this, by using the first reference frequency characteristic calculated in advance by the designer, it is possible to easily estimate the arrangement of the first housing and determine the first correction parameter.

[0205] (Technology 5) The audio playback system described in Technology 4, wherein the processor determines the first correction parameter that reduces the difference between the first reference frequency characteristic and the first frequency characteristic in a predetermined frequency range for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements.

[0206] For example, the first reference frequency characteristic is the frequency characteristic of a first reference test sound based on a test signal, calculated in a state where the entire audio reproduction system, including speaker characteristics, is designed so that the frequency characteristics of the audio signal are optimized in a predetermined arrangement (e.g., a standard "Free" arrangement). Therefore, by determining a first correction parameter that reduces the difference between the first frequency characteristic and the first reference frequency characteristic in a predetermined frequency band, it is possible to improve the frequency characteristic of the audio signal even at the listening position in the user's space.

[0207] However, the first reference frequency characteristic is a frequency characteristic calculated when the first test housing is in a specific position, and the arrangement of the first test housing and the arrangement of the first housing may differ, and the frequency range in which the first reference frequency characteristic and the first frequency characteristic should be compared will differ depending on the arrangement of the first housing. In response to this, the designer can determine in advance, for each of a plurality of predetermined arrangements, the frequency range in which the first reference frequency characteristic and the first frequency characteristic should be compared by conducting experiments or simulations. Therefore, it is possible to determine the first correction parameter according to the arrangement of the first housing.

[0208] (Technology 6) An audio reproduction system described in any one of Technology 2, 4, and 5, wherein the first reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up a first reference test audio based on the test signal output from a first test speaker provided in a first test enclosure installed at a specific position in the test space, using a first test microphone provided in the first test enclosure.

[0209] In this way, the first reference frequency characteristic can be calculated.

[0210] (Technology 7) The audio reproduction system described in Technology 1 further includes a first communication interface provided in the first housing and capable of transmitting an audio signal, a second housing installed in the space, a second communication interface provided in the second housing and capable of receiving the audio signal from the first communication interface, and a second speaker provided in the second housing and outputting audio based on the audio signal received by the second communication interface, wherein the processor further causes the second speaker to output a second test audio based on the test signal by transmitting the test signal from the first communication interface to the second communication interface, acquires a second picked-up signal indicating the second test audio picked up by the first microphone, calculates second frequency characteristics of the second picked-up signal, estimates the position of the second housing in the space based on the second frequency characteristics, and determines second correction parameters based on the position of the second housing, and the equalizer unit further corrects the frequency characteristics of the input audio signal using the second correction parameter to generate a second corrected audio signal, and the second speaker outputs audio based on the second corrected audio signal.

[0211] According to this, the first microphone required to determine the second correction parameter for the second speaker provided in the second housing is pre-installed in the first housing, so the user does not need to separately prepare special equipment such as a microphone in addition to what is necessary for normal playback. Furthermore, the location of the second housing is automatically estimated from the second frequency characteristic of the second pickup signal indicating the second test audio picked up by the first microphone, and the second correction parameter is automatically determined from the estimated location of the second housing. Therefore, the user does not need the skills or specialized knowledge to pick up an audio signal at the listening position and determine the correction parameter. Therefore, even if the audio playback system has multiple speakers and only one microphone in the housing, a user without specialized knowledge can automatically improve the frequency characteristic at the listening position with one touch, easily achieving the performance intended by the designer.

[0212] (Technology 8) The processor estimates the position of the first housing by comparing a first reference frequency characteristic for the first housing with the first frequency characteristic, and estimates the position of the second housing by comparing a second reference frequency characteristic for the second housing with the second frequency characteristic, in the audio playback system described in Technology 6.

[0213] According to this, the comparison result between the first reference frequency characteristic and the first frequency characteristic changes in response to changes in the placement of the first housing. In other words, there is a correlation between the comparison result between the first reference frequency characteristic and the first frequency characteristic and the placement of the first housing. Therefore, by comparing the first reference frequency characteristic and the first frequency characteristic, it is possible to easily estimate the placement of the first housing. Furthermore, the comparison result between the second reference frequency characteristic and the second frequency characteristic changes in response to changes in the placement of the second housing. In other words, there is a correlation between the comparison result between the second reference frequency characteristic and the second frequency characteristic and the placement of the second housing. Therefore, it is possible to easily estimate the placement of the second housing by comparing the second reference frequency characteristic and the second frequency characteristic.

[0214] (Technology 9) An audio playback system described in Technology 7 or 8, wherein the processor determines a predetermined correction parameter for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements as the first correction parameter, and determines a predetermined correction parameter for a predetermined arrangement estimated as the arrangement of the second housing from among the plurality of predetermined arrangements as the second correction parameter.

[0215] This allows a designer to determine in advance optimal correction parameters for each of a plurality of predetermined layouts by conducting experiments, simulations, etc. Therefore, by using the correction parameters predetermined for the predetermined layout estimated as the layout of the first housing as the first correction parameters, the first correction parameters can be easily determined. Also, by using the correction parameters predetermined for the predetermined layout estimated as the layout of the second housing as the second correction parameters, the second correction parameters can be easily determined.

[0216] (Technology 10) The processor uses the first reference frequency characteristic and the second reference frequency characteristic to estimate the arrangement of the first housing and the arrangement of the second housing, and to determine the first correction parameter and the second correction parameter, in the audio reproduction system described in Technology 8.

[0217] According to this, by using the first reference frequency characteristic and the second reference frequency characteristic calculated in advance by the designer, it is possible to easily estimate the arrangement of the first housing and the second housing, and to easily determine the first correction parameter and the second correction parameter.

[0218] (Technology 11) The processor determines the first correction parameter that reduces the difference between the first reference frequency characteristic and the first frequency characteristic in a predetermined frequency range for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements, and determines the second correction parameter that reduces the difference between the second reference frequency characteristic and the second frequency characteristic in a predetermined frequency range for a predetermined arrangement estimated as the arrangement of the second housing from among the plurality of predetermined arrangements.

[0219] For example, the first reference frequency characteristic is the frequency characteristic of a first reference test sound based on a test signal, calculated in a state where the entire audio reproduction system, including speaker characteristics, is designed so that the frequency characteristics of the audio signal are optimized in a standard predetermined arrangement (e.g., a standard "Free" arrangement). Furthermore, for example, the second reference frequency characteristic is the frequency characteristic of a second reference test sound based on a test signal, calculated in a state where the entire audio reproduction system, including speaker characteristics, is designed so that the frequency characteristics of the audio signal are optimized in a standard predetermined arrangement. Therefore, by determining a first correction parameter that reduces the difference between the first frequency characteristic and the first reference frequency characteristic in a predetermined frequency band and determining a second correction parameter that reduces the difference between the second frequency characteristic and the second reference frequency characteristic in the predetermined frequency band, it is possible to improve the frequency characteristic of the audio signal even at the listening position in the user's space.

[0220] However, the first reference frequency characteristic is a frequency characteristic calculated when the first test housing is in a specific position, and the position of the first test housing may differ from the position of the first housing, and the frequency range in which the first reference frequency characteristic and the first frequency characteristic should be compared will differ depending on the position of the first housing.Furthermore, the second reference frequency characteristic is a frequency characteristic calculated when the second test housing is in a specific position, and the position of the second test housing may differ from the position of the second housing, and the frequency range in which the second reference frequency characteristic and the second frequency characteristic should be compared will differ depending on the position of the second housing.

[0221] In response to this, the designer can determine in advance, for each of a plurality of predetermined arrangements, the frequency range in which the first reference frequency characteristic should be compared with the first frequency characteristic and the frequency range in which the second reference frequency characteristic should be compared with the second frequency characteristic, by performing experiments, simulations, etc. Therefore, it is possible to determine the first correction parameter and the second correction parameter according to the arrangement of the first housing and the second housing.

[0222] (Technology 12) An audio reproduction system described in any one of Techniques 8, 10, and 11, wherein the first reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by collecting, with a first test microphone provided in a first test housing, a first reference test sound based on the test signal output from a first test speaker provided in a first test housing installed at a specific position in the test space, and the second reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by collecting, with the first test microphone provided in the first test housing, a second reference test sound based on the test signal output from a second test speaker provided in a second test housing installed at a specific position in the test space.

[0223] In this manner, the first reference frequency characteristic and the second reference frequency characteristic can be calculated.

[0224] (Technology 13) The present invention further includes a first communication interface provided in the first housing and capable of transmitting an audio signal, a second housing installed in the space, a second communication interface provided in the second housing and capable of receiving the audio signal from the first communication interface, a second speaker provided in the second housing and outputting audio based on the audio signal received by the second communication interface, and a second microphone provided in the second housing, wherein the processor further controls the first communication interface to transmit the test signal to the second communication interface, thereby generating a signal corresponding to the test signal. and outputting a second test sound based on the second housing from the second speaker, acquiring a third picked-up signal indicating the second test sound picked up by the second microphone, calculating a third frequency characteristic of the third picked-up signal, estimating a position of the second housing in the space based on the third frequency characteristic, and determining a second correction parameter based on the position of the second housing, wherein the equalizer unit further generates a second corrected sound signal by correcting the frequency characteristic of the input sound signal using the second correction parameter, and the second speaker outputs sound based on the second corrected sound signal.

[0225] According to this, the second microphone required to determine the second correction parameter for the second speaker provided in the second housing is pre-installed in the second housing, so the user does not need to separately prepare special equipment such as a microphone in addition to what is necessary for normal playback. Furthermore, the location of the second housing is automatically estimated from the third frequency characteristic of the third collected signal indicating the second test audio picked up by the second microphone, and the second correction parameter is automatically determined from the estimated location of the second housing. Therefore, the user does not need the skills or specialized knowledge to collect audio signals at the listening position and determine the correction parameter. Therefore, even if the audio playback system includes multiple speakers and multiple microphones, a user without specialized knowledge can automatically improve the frequency characteristic at the listening position with one touch, easily achieving the performance intended by the designer.

[0226] (Technology 14) The processor estimates the position of the first housing by comparing a first reference frequency characteristic for the first housing with the first frequency characteristic, and estimates the position of the second housing by comparing a third reference frequency characteristic for the second housing with the third frequency characteristic, in the audio playback system described in Technology 13.

[0227] According to this, the comparison result between the first reference frequency characteristic and the first frequency characteristic changes in response to changes in the placement of the first housing. In other words, there is a correlation between the comparison result between the first reference frequency characteristic and the first frequency characteristic and the placement of the first housing. Therefore, by comparing the first reference frequency characteristic and the first frequency characteristic, it is possible to easily estimate the placement of the first housing. Furthermore, the comparison result between the third reference frequency characteristic and the third frequency characteristic changes in response to changes in the placement of the second housing. In other words, there is a correlation between the comparison result between the third reference frequency characteristic and the third frequency characteristic and the placement of the second housing. Therefore, it is possible to easily estimate the placement of the second housing by comparing the third reference frequency characteristic and the third frequency characteristic.

[0228] (Technology 15) An audio playback system described in Technology 13 or 14, wherein the processor determines a predetermined correction parameter for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements as the first correction parameter, and determines a predetermined correction parameter for a predetermined arrangement estimated as the arrangement of the second housing from among the plurality of predetermined arrangements as the second correction parameter.

[0229] This allows a designer to determine in advance optimal correction parameters for each of a plurality of predetermined layouts by conducting experiments, simulations, etc. Therefore, by using the correction parameters predetermined for the predetermined layout estimated as the layout of the first housing as the first correction parameters, the first correction parameters can be easily determined. Also, by using the correction parameters predetermined for the predetermined layout estimated as the layout of the second housing as the second correction parameters, the second correction parameters can be easily determined.

[0230] (Technology 16) The processor uses the first reference frequency characteristic, the second reference frequency characteristic for the second housing, the third reference frequency characteristic, and the fourth reference frequency characteristic for the first housing to estimate the arrangement of the first housing and the arrangement of the second housing, and to determine the first correction parameter and the second correction parameter, in the audio reproduction system described in Technology 14.

[0231] According to this, by using the first reference frequency characteristic, the second reference frequency characteristic, the third reference frequency characteristic, and the fourth reference frequency characteristic calculated in advance by the designer, it is possible to easily estimate the arrangement of the first housing and the second housing, and to easily determine the first correction parameter and the second correction parameter.

[0232] (Technology 17) The processor further acquires a second picked-up signal indicating the second test sound picked up by the first microphone, acquires a fourth picked-up signal indicating the first test sound picked up by the second microphone, calculates second frequency characteristics of the second picked-up signal, calculates fourth frequency characteristics of the fourth picked-up signal, and calculates a difference between the first reference frequency characteristic and the first frequency characteristic, which is predetermined for the predetermined arrangement estimated as the arrangement of the first housing, for each frequency range predetermined for the predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements. and determining, for each frequency range predetermined for a predetermined arrangement estimated as the arrangement of the second housing from among the plurality of predetermined arrangements, the second correction parameter that reduces the difference between the second reference frequency characteristic and the second frequency characteristic or the difference between the third reference frequency characteristic and the third frequency characteristic, which is predetermined for the predetermined arrangement estimated as the arrangement of the second housing.

[0233] For example, the first reference frequency characteristic, the second reference frequency characteristic, the third reference frequency characteristic, and the fourth reference frequency characteristic are frequency characteristics of a reference test sound based on a test signal, calculated in a state where the entire audio reproduction system, including speaker characteristics, is designed so that the frequency characteristics of the audio signal are optimized in a predetermined arrangement (e.g., a standard "Free" arrangement). Therefore, by determining a first correction parameter that reduces the difference between the first frequency characteristic and the first reference frequency characteristic in a predetermined frequency band, and determining a second correction parameter that reduces the difference between the third frequency characteristic and the third reference frequency characteristic in the predetermined frequency band, it is possible to improve the frequency characteristics of the audio signal even at the listening position in the user's space.

[0234] However, the first reference frequency characteristic is a frequency characteristic calculated when the first test housing is in a specific position, and the position of the first test housing may differ from the position of the first housing, so the frequency range in which the first reference frequency characteristic should be compared with the first frequency characteristic varies depending on the position of the first housing. Furthermore, the third reference frequency characteristic is a frequency characteristic calculated when the second test housing is in a specific position, and the position of the second test housing may differ from the position of the second housing, so the frequency range in which the third reference frequency characteristic should be compared with the third frequency characteristic varies depending on the position of the second housing. Furthermore, since it is possible to calculate the second frequency characteristic of a second picked-up signal representing the second test sound of the second speaker picked up by the first microphone and the fourth frequency characteristic of a fourth picked-up signal representing the first test sound of the first speaker picked up by the second microphone, there may be a frequency range in which it is better to compare the fourth reference frequency characteristic with the fourth frequency characteristic, depending on the position of the first housing. Furthermore, depending on the arrangement of the second housing, there may be a frequency range in which it is better to compare the second reference frequency characteristic with the second frequency characteristic.

[0235] In response to this, the designer can determine in advance, for each of a plurality of predetermined arrangements, the frequency range in which the first reference frequency characteristic, the second reference frequency characteristic, the third reference frequency characteristic, or the fourth reference frequency characteristic should be compared with the first frequency characteristic, the second frequency characteristic, the third frequency characteristic, or the fourth frequency characteristic, by performing an experiment, a simulation, etc. Therefore, it is possible to determine the first correction parameter and the second correction parameter according to the arrangement of the first housing and the second housing.

[0236] (Technology 18) The audio reproduction system described in Technology 16 or 17, wherein the first reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by collecting, with a first test microphone provided in a first test housing, a first reference test sound based on the test signal output from a first test speaker provided in a first test housing installed at a specific position in the test space; the second reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by collecting, with the first test microphone provided in the first test housing, a second reference test sound based on the test signal output from a second test speaker provided in a second test housing installed at a specific position in the test space; the third reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by collecting, with the second test microphone provided in the second test housing, the second reference test sound; and the fourth reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by collecting, with the second test microphone provided in the second test housing, the first reference test sound.

[0237] In this manner, the first reference frequency characteristic, the second reference frequency characteristic, the third reference frequency characteristic, and the fourth reference frequency characteristic can be calculated.

[0238] (Technology 19) An audio reproduction method executed by an audio reproduction system, the audio reproduction system comprising a first housing installed in a space, a first speaker provided in the first housing, and a first microphone provided in the first housing, the audio reproduction method including: outputting a first test audio based on a test signal to the first speaker; acquiring a first picked-up signal indicating the first test audio picked up by the first microphone; calculating a first frequency characteristic of the first picked-up signal; estimating the position of the first housing in the space based on the first frequency characteristic; determining a first correction parameter based on the position of the first housing; correcting the frequency characteristic of an input audio signal input to the audio reproduction system using the first correction parameter to generate a first corrected audio signal; and outputting audio based on the first corrected audio signal to the first speaker.

[0239] This makes it possible to provide an audio reproduction method that can easily achieve the performance intended by the designer.

[0240] (Technology 20) A program for causing a computer to execute the audio playback method described in Technology 19.

[0241] This makes it possible to provide a program that can easily achieve the performance intended by the designer.

[0242] The present disclosure can be applied to an audio reproduction system for reproducing audio, etc.

[0243] 1, 2, 3 Audio reproduction system 100, 101, 102 First housing 110, 110a, 110b Processor 111, 111a Test signal generator 112 Signal switcher 113, 113a, 113b Sound collection measurement device 114, 114a, 114b Correction parameter generator 115 Frequency characteristic analysis unit 116 Comparison analysis unit 117, 117a Determination unit 120, 120a Equalizer 130 First microphone 140 Input terminal 150, 220 Amplifier 160 First speaker 170, 170a First communication I / F 180 Memory 201, 202 Second housing 210, 210a Second communication I / F 230 Second speaker 240 Second microphone

Claims

1. An audio reproduction system comprising: a first housing installed in a space; a first speaker provided in the first housing; a first microphone provided in the first housing; a processor; and an equalizer unit, wherein the processor causes the first speaker to output a first test sound based on a test signal, acquires a first picked-up signal indicating the first test sound picked up by the first microphone, calculates a first frequency characteristic of the first picked-up signal, estimates the arrangement of the first housing in the space based on the first frequency characteristic, and determines a first correction parameter based on the arrangement of the first housing, the equalizer unit generates a first corrected audio signal by correcting the frequency characteristic of an input audio signal input to the audio reproduction system using the first correction parameter, and the first speaker outputs audio based on the first corrected audio signal.

2. The audio reproduction system according to claim 1, wherein the processor estimates the location of the first housing by comparing a first reference frequency characteristic for the first housing with the first frequency characteristic.

3. The audio reproduction system of claim 1 or 2, wherein the processor determines, as the first correction parameter, a correction parameter that is predetermined for a predetermined arrangement that is estimated as the arrangement of the first housing from among a plurality of predetermined arrangements.

4. The audio reproduction system according to claim 2, wherein the processor uses the first reference frequency characteristic to estimate the arrangement of the first housing and to determine the first correction parameter.

5. The audio reproduction system of claim 4, wherein the processor determines the first correction parameter that reduces the difference between the first reference frequency characteristic and the first frequency characteristic in a predetermined frequency range for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements.

6. The audio reproduction system of any one of claims 2, 4, and 5, wherein the first reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up a first reference test sound based on the test signal output from a first test speaker provided in a first test housing installed at a specific position in a test space, by a first test microphone provided in the first test housing.

7. The device further comprises a first communication interface provided in the first housing and capable of transmitting an audio signal; a second housing installed in the space; a second communication interface provided in the second housing and capable of receiving the audio signal from the first communication interface; and a second speaker provided in the second housing and outputting an audio based on the audio signal received by the second communication interface, wherein the processor further causes the second speaker to output a second test audio based on the test signal by transmitting the test signal from the first communication interface to the second communication interface; acquires a second picked-up signal indicating the second test audio picked up by the first microphone; calculates second frequency characteristics of the second picked-up signal; estimates the location of the second housing in the space based on the second frequency characteristics; and determines a second correction parameter based on the location of the second housing; the equalizer unit further generates a second corrected audio signal by correcting the frequency characteristics of the input audio signal using the second correction parameter; and the second speaker outputs an audio based on the second corrected audio signal.

2. The audio reproduction system of claim 1.

8. The audio playback system of claim 7, wherein the processor estimates the location of the first housing by comparing a first reference frequency characteristic for the first housing with the first frequency characteristic, and estimates the location of the second housing by comparing a second reference frequency characteristic for the second housing with the second frequency characteristic.

9. The audio playback system of claim 7 or 8, wherein the processor determines, as the first correction parameter, a correction parameter that is predetermined for a predetermined arrangement that is estimated as the arrangement of the first housing from among a plurality of predetermined arrangements, and determines, as the second correction parameter, a correction parameter that is predetermined for a predetermined arrangement that is estimated as the arrangement of the second housing from among the plurality of predetermined arrangements.

10. The audio reproduction system of claim 8, wherein the processor uses the first reference frequency characteristic and the second reference frequency characteristic to estimate the arrangement of the first housing and the arrangement of the second housing, and to determine the first correction parameter and the second correction parameter.

11. The audio playback system of claim 10, wherein the processor determines the first correction parameter that reduces the difference between the first reference frequency characteristic and the first frequency characteristic in a predetermined frequency range for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements, and determines the second correction parameter that reduces the difference between the second reference frequency characteristic and the second frequency characteristic in a predetermined frequency range for a predetermined arrangement estimated as the arrangement of the second housing from among the plurality of predetermined arrangements.

12. The audio reproduction system described in any one of claims 8, 10 and 11, wherein the first reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up, by a first test microphone provided in the first test housing, a first reference test sound based on the test signal output from a first test speaker provided in a first test housing installed at a specific position in the test space, and the second reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up, by the first test microphone provided in the first test housing, a second reference test sound based on the test signal output from a second test speaker provided in a second test housing installed at a specific position in the test space.

13. The device further comprises a first communication interface provided in the first housing and capable of transmitting an audio signal; a second housing installed in the space; a second communication interface provided in the second housing and capable of receiving the audio signal from the first communication interface; a second speaker provided in the second housing and outputting an audio based on the audio signal received by the second communication interface; and a second microphone provided in the second housing, wherein the processor further causes the second speaker to output a second test audio based on the test signal by transmitting the test signal from the first communication interface to the second communication interface; acquires a third picked-up signal indicating the second test audio picked up by the second microphone; calculates a third frequency characteristic of the third picked-up signal; estimates the arrangement of the second housing in the space based on the third frequency characteristic; and determines a second correction parameter based on the arrangement of the second housing; and the equalizer unit further generates a second corrected audio signal by correcting the frequency characteristic of the input audio signal using the second correction parameter, The audio reproduction system according to claim 1 , wherein the second speaker outputs an audio based on the second corrected audio signal.

14. The audio playback system of claim 13, wherein the processor estimates the location of the first housing by comparing a first reference frequency characteristic for the first housing with the first frequency characteristic, and estimates the location of the second housing by comparing a third reference frequency characteristic for the second housing with the third frequency characteristic.

15. The audio playback system of claim 13 or 14, wherein the processor determines a predetermined correction parameter for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements as the first correction parameter, and determines a predetermined correction parameter for a predetermined arrangement estimated as the arrangement of the second housing from among the plurality of predetermined arrangements as the second correction parameter.

16. The audio reproduction system of claim 14, wherein the processor estimates the arrangement of the first housing and the arrangement of the second housing, and determines the first correction parameter and the second correction parameter, using the first reference frequency characteristic, the second reference frequency characteristic for the second housing, the third reference frequency characteristic, and the fourth reference frequency characteristic for the first housing.

17. The processor further acquires a second pickup signal indicating the second test sound picked up by the first microphone, acquires a fourth pickup signal indicating the first test sound picked up by the second microphone, calculates a second frequency characteristic of the second pickup signal, calculates a fourth frequency characteristic of the fourth pickup signal, determines the first correction parameter for each predetermined frequency range for a predetermined arrangement estimated as the arrangement of the first housing from among a plurality of predetermined arrangements, which reduces a difference between the first reference frequency characteristic and the first frequency characteristic or a difference between the fourth reference frequency characteristic and the fourth frequency characteristic, which is predetermined for the predetermined arrangement estimated as the arrangement of the first housing, and determines the second correction parameter for each predetermined frequency range for a predetermined arrangement estimated as the arrangement of the second housing from among the plurality of predetermined arrangements, which reduces a difference between the second reference frequency characteristic and the second frequency characteristic or a difference between the third reference frequency characteristic and the third frequency characteristic, which is predetermined for the predetermined arrangement estimated as the arrangement of the second housing.

17. An audio reproduction system according to claim 16.

18. The audio reproduction system described in claim 16 or 17, wherein the first reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up, by a first test microphone provided in the first test housing, a first reference test sound based on the test signal output from a first test speaker provided in a first test housing installed at a specific position in the test space; the second reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up, by the first test microphone provided in the first test housing, a second reference test sound based on the test signal output from a second test speaker provided in a second test housing installed at a specific position in the test space; the third reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up, by the second test microphone provided in the second test housing, the second reference test sound; and the fourth reference frequency characteristic is a frequency characteristic calculated in advance from a picked-up signal obtained by picking up, by the second test microphone provided in the second test housing, the first reference test sound.

19. An audio reproduction method executed by an audio reproduction system, the audio reproduction system comprising: a first housing installed in a space; a first speaker provided in the first housing; and a first microphone provided in the first housing, the audio reproduction method comprising the steps of: outputting a first test audio based on a test signal to the first speaker; acquiring a first picked-up signal indicating the first test audio picked up by the first microphone; calculating a first frequency characteristic of the first picked-up signal; estimating the arrangement of the first housing in the space based on the first frequency characteristic; determining a first correction parameter based on the arrangement of the first housing; correcting the frequency characteristic of an input audio signal input to the audio reproduction system using the first correction parameter to generate a first corrected audio signal; and outputting audio based on the first corrected audio signal to the first speaker.

20. A program for causing a computer to execute the audio reproducing method according to claim 19.

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