Acoustic reproduction method, computer program, and acoustic reproduction device

Abstract

To provide an acoustic reproduction method for improving the perception level of a sound arriving from behind a listener.SOLUTION: An acoustic reproduction method includes: a signal acquisition step of acquiring a first audio signal corresponding to a first sound arriving at a listener from a first area with extent, and a second audio signal corresponding to a second sound arriving at the listener from a point in a first direction; an information acquisition step of acquiring direction information that is information on a direction in which the head of the listener is directed; a correction processing step of executing correction processing on at least one of the acquired first audio signal and the acquired second audio signal when the first area and the point are determined to be included in a rear range on the basis of the acquired direction information; and a mixing processing step of mixing the first audio signal and the second audio signal and outputting the mixed signals to an output channel.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a sound reproduction method and the like. [Background technology]

[0002] Patent Document 1 proposes a technology relating to a stereophonic sound reproduction system that realizes realistic sound by outputting sound from a plurality of speakers arranged around a listener. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-287002 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, humans (here, listeners who hear sound) perceive sounds that reach them from behind them at a lower level than sounds that reach them from in front of them, among sounds that reach them from the surroundings.

[0005] Therefore, an object of the present disclosure is to provide a sound reproduction method that improves the perceived level of sounds arriving from behind the listener. [Means for solving the problem]

[0006] A sound reproduction method according to one aspect of the present disclosure includes a signal acquisition step of acquiring a first audio signal corresponding to a first sound reaching a listener from a first region having an extension in a sound reproduction space, and a second audio signal corresponding to a second sound reaching the listener from a point in a first direction in the sound reproduction space; an information acquisition step of acquiring directional information that is information on a direction in which the head of the listener is facing; and, when the direction in which the head of the listener is facing is defined as forward and a range behind the forward range is defined as a rear range, if it is determined that the first region and the point are included in the rear range based on the acquired directional information, and a mixing processing step of mixing the first audio signal and the second audio signal and outputting the mixed signal to an output channel, wherein, when a range behind the direction in which the head of the listener is facing is defined as forward, if it is determined based on the acquired direction information that at least a part of the first region and the point are included in the rear range, at least one of the first audio signal to be mixed and the second audio signal to be mixed is a signal to which the correction processing has been applied.

[0007] A program according to one aspect of the present disclosure causes a computer to execute the above-described sound reproduction method.

[0008] A sound reproduction device according to one aspect of the present disclosure includes a signal acquisition unit that acquires a first audio signal corresponding to a first sound that reaches a listener from a first area having a spread in a sound reproduction space, and a second audio signal corresponding to a second sound that reaches the listener from a point in a first direction in the sound reproduction space, and an information acquisition unit that acquires directional information that is information about a direction in which the head of the listener is facing, and when the direction in which the head of the listener is facing is defined as a forward direction and a rear range is defined as a rear range, the acquired first audio signal and the acquired audio signal are outputted when it is determined that the first area and the point are included in the rear range based on the acquired directional information. and a mixing processing unit that mixes the first audio signal and the second audio signal and outputs the mixed signal to an output channel, wherein, when a range behind the direction in which the head of the listener is facing is defined as forward, the mixing processing unit determines, based on the acquired direction information, that at least a part of the first region and the point are included in the rear range, that at least one of the first audio signal and the second audio signal to be mixed is a signal that has been subjected to the correction processing.

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

[0010] The sound reproduction method according to one aspect of the present disclosure can improve the perceived level of sounds arriving from behind the listener. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a functional configuration of a sound reproduction device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of use of sounds output from a plurality of speakers according to the embodiment. [Figure 3] FIG. 3 is a flowchart of a first operation example of the sound reproducing device according to the embodiment. [Figure 4] FIG. 4 is a schematic diagram for explaining an example of a determination made by the correction processing unit according to the embodiment. [Figure 5] FIG. 5 is a schematic diagram for explaining another example of the determination made by the correction processing unit according to the embodiment. [Figure 6] FIG. 6 is a schematic diagram for explaining another example of the determination made by the correction processing unit according to the embodiment. [Figure 7] FIG. 7 is a schematic diagram for explaining another example of the determination made by the correction processing unit according to the embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of correction processing according to the first example of the operation example 1 according to the embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of correction processing according to the second example of the first operation example according to the embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of correction processing according to the third example of the first operation example according to the embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of correction processing according to the fourth example of the first operation example according to the embodiment. [Figure 12] FIG. 12 is a flowchart of a second operation example of the sound reproducing device according to the embodiment. [Figure 13] FIG. 13 is a diagram illustrating an example of correction processing according to the second operation example according to the embodiment. [Figure 14] FIG. 14 is a diagram illustrating another example of the correction process according to the second operation example according to the embodiment. [Figure 15] FIG. 15 is a diagram illustrating another example of the correction process according to the second operation example according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Findings that formed the basis of this disclosure) BACKGROUND ART Conventionally, there is known a technology relating to sound reproduction that realizes realistic sound by outputting sounds represented by a plurality of different audio signals from a plurality of speakers arranged around a listener.

[0013] For example, the stereophonic sound reproduction system disclosed in Patent Document 1 includes main speakers, surround speakers, and a stereophonic sound reproduction device.

[0014] The main speaker amplifies the sound indicated by the main audio signal at a position where the listener is located within the directivity angle, and the surround speaker amplifies the sound indicated by the surround audio signal toward the walls of the sound field space, and the stereophonic sound reproduction device amplifies each speaker individually.

[0015] The stereophonic sound reproduction device also includes a signal adjusting means, a delay time adding means, and an output means. The signal adjusting means adjusts the frequency characteristics of the surround audio signal based on the propagation environment during sound amplification. The delay time adding means adds a delay time corresponding to the surround signal to the main audio signal. The output means outputs the main audio signal with the delay time added to the main speakers, and outputs the adjusted surround audio signal to the surround speakers.

[0016] Such a stereophonic sound reproduction system makes it possible to create a sound field space that gives a high sense of realism.

[0017] Incidentally, humans (here, listeners who hear sound) perceive sounds that arrive from behind them at a lower level than sounds that arrive from in front of them among sounds that reach them from the surroundings. For example, humans have a perceptual characteristic (more specifically, an auditory characteristic) that makes it difficult for them to perceive the position or direction of sounds that arrive from behind them. This perceptual characteristic is a characteristic derived from the shape of the human pinna and its discrimination limit.

[0018] Furthermore, when two types of sounds (e.g., a target sound and an environmental sound) arrive from behind the listener, one sound (e.g., the target sound) may be buried in the other sound (e.g., the environmental sound). In this case, it becomes difficult for the listener to hear the target sound, and therefore it becomes difficult for the listener to perceive the position or direction of the target sound arriving from behind the listener.

[0019] For example, even in the stereophonic sound reproduction system disclosed in Patent Document 1, when sounds represented by a main audio signal and sounds represented by a surround audio signal arrive from behind the listener, the listener has difficulty perceiving the sounds represented by the main audio signal. Therefore, there is a demand for an audio reproduction method that can improve the perception level of sounds arriving from behind the listener.

[0020] Therefore, a sound reproduction method according to one aspect of the present disclosure includes: a signal acquisition step of acquiring a first audio signal corresponding to an environmental sound that reaches the listener from a first range, which is a first angle range in a sound reproduction space, and a second audio signal corresponding to a target sound that reaches the listener from a point in a first direction in the sound reproduction space; an information acquisition step of acquiring directional information that is information about a direction in which the head of the listener is facing; a correction processing step of, when it is determined based on the acquired directional information that the first range and the point are included in a rear range when the direction in which the head of the listener is facing is defined as forward, performing a correction processing on at least one of the acquired first audio signal and the acquired second audio signal so that there is no overlap between the first range and the point when the sound reproduction space is viewed in a predetermined direction; and a mixing processing step of mixing at least one of the first audio signal that has been subjected to the correction processing and the second audio signal that has been subjected to the correction processing and outputting the resultant signal to an output channel.

[0021] As a result, when the first range and the point are included in the rear range, correction processing is performed so that the first range and the point do not overlap. This prevents the target sound, whose sound image is localized at this point, from being buried in the environmental sound, whose sound image is localized in the first range, making it easier for the listener to hear the target sound reaching the listener from behind. In other words, a sound reproduction method is realized that can improve the perception level of sound reaching the listener from behind.

[0022] For example, the first range is a range behind the reference direction determined by the position of the output channel.

[0023] This makes it easier for the listener to hear the target sound arriving from behind the listener, even when the environmental sound reaches the listener from a range behind the reference direction.

[0024] For example, the predetermined direction is a second direction that is a direction from above the listener toward the listener.

[0025] This eliminates the overlap between the first range and the point when viewed from above the listener. As a result, the listener can more easily hear the target sound arriving from behind the listener. In other words, a sound reproduction method is realized that can improve the perceived level of sound arriving from behind the listener.

[0026] For example, the first range indicated by the first audio signal that has been subjected to the correction process includes a second range that is a second angle range and a third range that is a third angle range different from the second angle, and the environmental sound reaches the listener from the second range and the third range, and when the sound reproduction space is viewed in the second direction, the second range does not overlap with the point, and the third range does not overlap with the point.

[0027] As a result, environmental sounds reach the listener from two ranges, the second range and the third range, thereby improving the perceived level of sounds reaching the listener from behind, and realizing a sound reproduction method that allows the listener to hear a wide range of environmental sounds.

[0028] For example, the predetermined direction is a third direction that is a direction from the side of the listener toward the listener.

[0029] This eliminates the overlap between the first range and the point when viewed from the side of the listener. As a result, the listener can more easily hear the target sound arriving from behind the listener. In other words, a sound reproduction method is realized that can improve the perceived level of sound arriving from behind the listener.

[0030] For example, when the sound reproduction space is viewed in a third direction, the environmental sound represented by the acquired first audio signal reaches the listener from the first range, which is a fourth angle range in the sound reproduction space, and the target sound represented by the acquired second audio signal reaches the listener from the point in the fourth direction in the sound reproduction space. If it is determined that the fourth direction is included in the fourth angle, the correction processing step performs the correction processing on at least one of the acquired first audio signal and the acquired second audio signal so that there is no overlap between the fourth direction and the first range when the sound reproduction space is viewed in the third direction.

[0031] As a result, when viewed from the side of the listener, there is no overlap between the first range and a point, and there is no overlap between the first range and the fourth direction. As a result, the listener can easily hear the target sound arriving from behind the listener. In other words, a sound reproduction method is realized that can improve the perceived level of sound arriving from behind the listener.

[0032] For example, the correction process is a process of adjusting an output level of at least one of the acquired first audio signal and the acquired second audio signal.

[0033] This makes it easier for the listener to hear the target sound arriving from behind the listener, thus realizing a sound reproduction method that can further improve the perceived level of sound arriving from behind the listener.

[0034] For example, the mixing process step mixes at least one of the first audio signal on which the correction process has been performed and the second audio signal on which the correction process has been performed, and outputs the mixed signal to the plurality of output channels, and the correction process is a process of adjusting the output level of at least one of the acquired first audio signal and the acquired second audio signal in each of the plurality of output channels to which at least one of the acquired first audio signal and the acquired second audio signal is output.

[0035] This makes it easier for the listener to hear the target sound arriving from behind the listener, thus realizing a sound reproduction method that can further improve the perceived level of sound arriving from behind the listener.

[0036] For example, the correction process is a process of adjusting the output level of each of the plurality of output channels to which the second audio signal is output, based on the output level of the first audio signal corresponding to the environmental sound reaching the listener from the first range.

[0037] This makes it easier for the listener to hear the target sound arriving from behind the listener, thus realizing a sound reproduction method that can further improve the perceived level of sound arriving from behind the listener.

[0038] For example, the correction process is a process of adjusting an angle corresponding to a head-related transfer function convolved with at least one of the acquired first audio signal and the acquired second audio signal.

[0039] This makes it easier for the listener to hear the target sound arriving from behind the listener, thus realizing a sound reproduction method that can further improve the perceived level of sound arriving from behind the listener.

[0040] For example, the correction process is a process of adjusting an angle corresponding to a head-related transfer function to be convolved with the second audio signal based on an angle corresponding to a head-related transfer function to be convolved with the first audio signal so that the environmental sound represented by the first audio signal reaches the listener from the first range.

[0041] This makes it easier for the listener to hear the target sound arriving from behind the listener, thus realizing a sound reproduction method that can further improve the perceived level of sound arriving from behind the listener.

[0042] For example, a program according to one aspect of the present disclosure may be a program for causing a computer to execute the above-described sound reproducing method.

[0043] This allows the computer to execute the above-described sound reproduction method in accordance with the program.

[0044] For example, a sound reproduction device according to one aspect of the present disclosure includes: a signal acquisition unit that acquires a first audio signal corresponding to an environmental sound that reaches a listener from a first range, which is a first angle range in a sound reproduction space, and a second audio signal corresponding to a target sound that reaches the listener from a point in a first direction in the sound reproduction space; an information acquisition unit that acquires directional information that is information about a direction in which the head of the listener is facing; a correction processing unit that, when it is determined based on the directional information that the first range and the point are included in a rear range when the direction in which the head of the listener is facing is defined as a forward range, performs a correction process on at least one of the acquired first audio signal and the acquired second audio signal so that there is no overlap between the first range and the point when the sound reproduction space is viewed in a predetermined direction; and a mixing processing unit that mixes at least one of the first audio signal that has been subjected to the correction process and the second audio signal that has been subjected to the correction process, and outputs the result to an output channel.

[0045] As a result, when the first range and the point are included in the rear range, a correction process is performed so that the first range and the point do not overlap. This prevents the target sound, whose sound image is localized at this point, from being buried in the environmental sound, whose sound image is localized in the first range, making it easier for the listener to hear the target sound reaching the listener from behind. In other words, a sound reproduction device is realized that can improve the perception level of sound reaching the listener from behind.

[0046] Furthermore, these comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0047] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0048] The embodiments described below are all comprehensive or specific examples, and the numerical values, shapes, materials, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the scope of the claims.

[0049] In the following description, elements may be assigned ordinal numbers such as first, second, and third. These ordinal numbers are assigned to elements in order to identify them and do not necessarily correspond to a meaningful order. These ordinal numbers may be rearranged, newly added, or removed as appropriate.

[0050] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. In each figure, the same reference numerals are used to denote substantially the same components, and redundant explanations will be omitted or simplified.

[0051] In this specification, terms indicating relationships between elements such as parallel or perpendicular, and numerical ranges, are not expressions that only express a strict meaning, but also expressions that include a substantially equivalent range, for example, a difference of about a few percent.

[0052] (Embodiment 1) [composition] First, the configuration of a sound reproduction device 100 according to the first embodiment will be described. Fig. 1 is a block diagram showing the functional configuration of the sound reproduction device 100 according to this embodiment. Fig. 2 is a schematic diagram showing an example of using sounds output from a plurality of speakers 1, 2, 3, 4, and 5 according to this embodiment. Note that Fig. 2 is a diagram of the sound reproduction space as seen in a second direction, which is a direction from above the listener L toward the listener L. More specifically, the second direction is a direction from above the head of the listener L toward the listener L along a vertical downward direction.

[0053] The sound reproduction device 100 according to this embodiment processes a plurality of acquired audio signals and outputs the processed signals to a plurality of speakers 1, 2, 3, 4, and 5 in a sound reproduction space shown in Fig. 2, thereby allowing a listener L to hear sounds represented by the plurality of audio signals. More specifically, the sound reproduction device 100 is a stereophonic sound reproduction device that allows the listener L to hear stereophonic sounds in the sound reproduction space. The sound reproduction space is a space in which the listener L and a plurality of speakers 1, 2, 3, 4, and 5 are arranged. In this embodiment, as an example, the sound reproduction device 100 is used with the listener L standing on the floor of the sound reproduction space. Here, the floor is a surface parallel to the horizontal plane.

[0054] Furthermore, the sound reproducing device 100 processes the acquired audio signals based on the direction information output by the head sensor 300. The direction information is information about the direction in which the head of the listener L is facing. The direction in which the head of the listener L is facing also means the direction in which the face of the listener L is facing.

[0055] The head sensor 300 is a device that senses the direction in which the head of the listener L is facing. The head sensor 300 is preferably a device that senses information about 6 DOF (Degrees Of Freedom) of the head of the listener L. For example, the head sensor 300 is a device that is worn on the head of the listener L, and is preferably an inertial measurement unit (IMU), an accelerometer, a gyroscope, a magnetic sensor, or a combination of these.

[0056] As shown in Fig. 2, in this embodiment, a plurality of (here, five) speakers 1, 2, 3, 4, and 5 are arranged to surround the listener L. In the sound reproduction space shown in Fig. 2, to explain the directions, midnight, 3, 6, and 9 o'clock are shown corresponding to the times indicated on the clock face. Furthermore, the outline arrow indicates the direction in which the head of the listener L is facing, and in Fig. 2, the direction in which the head of the listener L, who is located at the center (also called the origin) of the clock face, is facing is the midnight direction. Hereinafter, the direction connecting the listener L and midnight may be referred to as the "midnight direction," and the same applies to the other times indicated on the clock face.

[0057] In this embodiment, the five speakers 1, 2, 3, 4, and 5 are composed of a center speaker, a front-right speaker, a rear-right speaker, a rear-left speaker, and a front-left speaker. Speaker 1, which is the center speaker, is placed at the 0 o'clock position. Speaker 2 is placed at the 1 o'clock position, speaker 3 at the 4 o'clock position, speaker 4 at the 8 o'clock position, and speaker 5 at the 11 o'clock position.

[0058] Each of the five speakers 1, 2, 3, 4, and 5 is a loudspeaker that outputs sounds represented by a plurality of audio signals output from the sound reproducing device 100.

[0059] The sound reproducing device 100 will now be described in further detail.

[0060] As shown in FIG. 1, the sound reproduction device 100 includes a signal processing unit 110, a first decoding unit 121, a second decoding unit 122, a first correction processing unit 131, a second correction processing unit 132, an information acquisition unit 140, and a mixing processing unit 150.

[0061] The signal processing unit 110 is a processing unit that acquires a plurality of audio signals. The signal processing unit 110 may acquire the plurality of audio signals by receiving a plurality of audio signals transmitted by other components not shown in Fig. 2, or may acquire the plurality of audio signals stored in a storage device not shown in Fig. 2. The plurality of audio signals acquired by the signal processing unit 110 are signals including a first audio signal and a second audio signal.

[0062] Here, the first audio signal and the second audio signal will be described.

[0063] The first audio signal is a signal corresponding to environmental sound that reaches the listener L from a first range R1, which is a first angle range in the sound reproduction space. More specifically, as shown in Fig. 2, the first audio signal is a signal corresponding to environmental sound that reaches the listener L from the first range R1, which is a first angle range based on the listener L, when the sound reproduction space is viewed in a second direction.

[0064] For example, the first range R1 is a range behind a reference direction determined by the positions of five speakers 1, 2, 3, 4, and 5, which are multiple output channels. In this embodiment, the reference direction is a direction from the listener L toward the center speaker, speaker 1, for example, the 0 o'clock direction, but is not limited to this. The direction behind the 0 o'clock direction, which is the reference direction, is the 6 o'clock direction, and the first range R1 may include the 6 o'clock direction, which is behind the reference direction. Furthermore, the first range R1 is a range from the 3 o'clock direction to the 9 o'clock direction (i.e., a range of 180° in terms of angle), as indicated by the double arrow in FIG. 2, and is the dotted area in FIG. 2. Note that the first range R1 is not limited to this and may be, for example, a range narrower or wider than 180°. Note that the reference direction is constant regardless of the direction in which the listener L's head is facing, and therefore the first range R1 is also constant regardless of the direction in which the listener L's head is facing.

[0065] Environmental sound is sound that reaches the listener L from all or part of the first range R1 having such a spread. Environmental sound is also sometimes called noise or ambient sound. In this embodiment, environmental sound is sound that reaches the listener L from all areas of the first range R1. Here, environmental sound is sound that reaches the listener L from the entire area marked with dots in FIG. 2. In other words, environmental sound is sound whose sound image is localized in the entire area marked with dots in FIG. 2, for example.

[0066] The second audio signal is a signal corresponding to a target sound that reaches the listener L from a point P in a first direction D1 in the sound reproduction space. More specifically, as shown in Fig. 2, the second audio signal is a signal corresponding to a target sound that reaches the listener L from a point P in the first direction D1 based on the listener L when the sound reproduction space is viewed in the second direction. Note that this point P is a point located in the first direction D1 and at a predetermined distance from the listener L, such as a black dot shown in Fig. 2.

[0067] The target sound is a sound whose sound image is localized at this black dot (point P). The target sound is a sound that reaches the listener L from a narrower range than the environmental sound. The target sound is a sound that is primarily heard by the listener L. The target sound can also be said to be a sound other than the environmental sound.

[0068] 2, in this embodiment, the first direction D1 is the 5 o'clock direction, and an arrow indicates that the target sound reaches the listener L from the first direction D1. Note that the first direction D1 is not limited to the 5 o'clock direction, and may be any other direction as long as it is a direction from the position where the sound image of the target sound is localized (here, point P) toward the listener L. Furthermore, the first direction D1 and point P are constant regardless of the direction in which the head of the listener L is facing.

[0069] In this embodiment, unless otherwise specified, point P in the first direction D1 is described as a point without size. However, this is not limited thereto, and point P in the first direction D1 may represent an area with size. Even in this case, the area indicating point P in the first direction D1 is a range narrower than the first range R1.

[0070] For an arrangement of five speakers 1, 2, 3, 4, and 5, environmental sounds are output using (selected from) multiple speakers so as to be distributed over a predetermined range. Target sounds are output using (selected from) one or more speakers so as to be localized at a predetermined position, with the output level from each speaker adjusted using a method called panning, for example. Panning is a method or phenomenon that expresses (makes people perceive) the localization of a virtual sound image between multiple speakers by controlling the output level difference between the multiple speakers.

[0071] The signal processing unit 110 will be described again.

[0072] Furthermore, the signal processing unit 110 performs processing to separate the multiple audio signals into first audio signals and second audio signals. The signal processing unit 110 outputs the separated first audio signals to the first decoding unit 121 and the separated second audio signals to the second decoding unit 122. In the present embodiment, the signal processing unit 110 is a demultiplexer as an example, but is not limited to this.

[0073] In this embodiment, it is preferable that the audio signals acquired by the signal processing unit 110 have been subjected to encoding processing such as MPEG-H 3D Audio (ISO / IEC 23008-3) (hereinafter referred to as MPEG-H 3D Audio). In other words, the signal processing unit 110 acquires the audio signals as encoded bitstreams.

[0074] The first decoding unit 121 and the second decoding unit 122, which are examples of a signal acquisition unit, acquire a plurality of audio signals. Specifically, the first decoding unit 121 acquires and decodes the first audio signal separated by the signal processing unit 110. The second decoding unit 122 acquires and decodes the second audio signal separated by the signal processing unit 110. The first decoding unit 121 and the second decoding unit 122 perform decoding processing based on the above-mentioned MPEG-H 3D Audio, etc.

[0075] The first decoding unit 121 outputs the decoded first audio signal to the first correction processing unit 131 , and the second decoding unit 122 outputs the decoded second audio signal to the second correction processing unit 132 .

[0076] Furthermore, the first decoding unit 121 outputs first information, which is information indicating a first range R1 included in the first audio signal, to the information obtaining unit 140. The second decoding unit 122 outputs second information, which is information indicating a point P in the first direction D1 included in the second audio signal, to the information obtaining unit 140.

[0077] The information acquisition unit 140 is a processing unit that acquires the direction information output from the head sensor 300. Furthermore, the information acquisition unit 140 acquires the first information output by the first decoding unit 121 and the second information output by the second decoding unit 122. The information acquisition unit 140 outputs the acquired direction information, first information, and second information to the first correction processing unit 131 and the second correction processing unit 132.

[0078] The first correction processing unit 131 and the second correction processing unit 132 are examples of a correction processing unit that performs correction processing on at least one of the first audio signal and the second audio signal.

[0079] The first correction processing unit 131 acquires the first audio signal acquired by the first decoding unit 121, and the directional information, first information, and second information acquired by the information acquisition unit 140. The second correction processing unit 132 acquires the second audio signal acquired by the second decoding unit 122, and the directional information, first information, and second information acquired by the information acquisition unit 140.

[0080] The correction processing units (first correction processing unit 131 and second correction processing unit 132) perform correction processing on at least one of the first audio signal and the second audio signal when a predetermined condition is satisfied based on the acquired direction information. More specifically, the first correction processing unit 131 performs correction processing on the first audio signal, and the second correction processing unit 132 performs correction processing on the second audio signal.

[0081] Here, when correction processing has been performed on the first audio signal and the second audio signal, the first correction processing unit 131 outputs the first audio signal that has been subjected to the correction processing, and the second correction processing unit 132 outputs the second audio signal that has been subjected to the correction processing, to the mixing processing unit 150.

[0082] Furthermore, if correction processing has been performed on the first audio signal, the first correction processing unit 131 outputs the first audio signal that has been subjected to correction processing, and the second correction processing unit 132 outputs the second audio signal that has not been subjected to correction processing, to the mixing processing unit 150.

[0083] Furthermore, when correction processing has been performed on the second audio signal, the first correction processing unit 131 outputs the first audio signal that has not been subjected to correction processing, and the second correction processing unit 132 outputs the second audio signal that has been subjected to correction processing, to the mixing processing unit 150.

[0084] The mixing processor 150 is a processor that mixes at least one of the first audio signal and the second audio signal that have been subjected to the correction processing by the correction processor, and outputs the mixed signal to a plurality of speakers 1, 2, 3, 4, and 5 that are a plurality of output channels.

[0085] More specifically, if the first audio signal and the second audio signal have been corrected, the mixing processing unit 150 mixes and outputs the corrected first audio signal and the second audio signal. If the first audio signal has been corrected, the mixing processing unit 150 mixes and outputs the corrected first audio signal and the uncorrected second audio signal. If the second audio signal has been corrected, the mixing processing unit 150 mixes and outputs the uncorrected first audio signal and the corrected second audio signal.

[0086] As another example, when headphones placed near the auricles of the listener L are used as the multiple output channels instead of multiple speakers 1, 2, 3, 4, and 5 placed around the listener L, the mixing processing unit 150 performs the following process. In this case, when mixing the first audio signal and the second audio signal, the mixing processing unit 150 performs a process of convolving a head-related transfer function and outputs the result.

[0087] In this way, when headphones are used instead of the multiple speakers 1, 2, 3, 4, and 5, the environmental sound is output so as to be distributed in a first range R1, for example, by performing a process of convolving a head-related transfer function with respect to the direction of the speaker arrangement virtually arranged around the listener L. Also, the target sound is output so as to be localized at a predetermined position of the listener L, for example, by performing a process of convolving a head-related transfer function.

[0088] [Example 1] Below, we will explain operation examples 1 and 2 of the sound reproducing method performed by the sound reproducing device 100. First, we will explain operation example 1. Fig. 3 is a flowchart of operation example 1 of the sound reproducing device 100 according to this embodiment.

[0089] The signal processing unit 110 acquires a plurality of audio signals (S10).

[0090] The signal processing unit 110 separates the plurality of audio signals acquired by the signal processing unit 110 into a first audio signal and a second audio signal (S20).

[0091] The first decoding unit 121 and the second decoding unit 122 respectively acquire the first audio signal and the second audio signal separated by the signal processing unit 110 (S30). Step S30 is a signal acquisition step. More specifically, the first decoding unit 121 acquires the first audio signal, and the second decoding unit 122 acquires the second audio signal. Furthermore, the first decoding unit 121 decodes the first audio signal, and the second decoding unit 122 decodes the second audio signal.

[0092] Here, the information acquiring unit 140 acquires direction information output by the head sensor 300 (S40). Step S40 is an information acquiring step. The information acquiring unit 140 also acquires first information indicating a first range R1 included in a first audio signal representing the environmental sound, and second information indicating a point P in a first direction D1 included in a second audio signal representing the target sound.

[0093] Furthermore, the information acquisition unit 140 outputs the acquired direction information, first information, and second information to the first correction processing unit 131 and the second correction processing unit 132 (that is, the correction processing units).

[0094] The correction processing unit acquires a first audio signal, a second audio signal, direction information, first information, and second information. Here, the correction processing unit determines whether a predetermined condition is satisfied based on the acquired direction information. That is, the correction processing unit determines whether the first range R1 and the point P are included in the rear range RB based on the acquired direction information (S50). More specifically, the correction processing unit determines whether the first range R1 and the point P are included in the rear range RB when the sound reproduction space is viewed in the second direction based on the acquired direction information, first information, and second information. It can also be said that the correction processing unit determines the degree of dispersion of the first range R1, the point P, and the rear range RB.

[0095] Here, the determination made by the correction processing unit and the rear range RB will be described with reference to FIGS.

[0096] 4 to 7 are schematic diagrams illustrating an example of a determination made by the correction processing unit according to the present embodiment. More specifically, in FIGS. 4, 5, and 7, the correction processing unit determines that the first range R1 and point P are included in the rear range RB, and in FIG. 6, the correction processing unit determines that the first range R1 and point P are not included in the rear range RB. Also, FIGS. 4, 5, and 6 show how the direction in which the head of the listener L faces changes clockwise in this order. All of FIGS. 4 to 7 are views of the sound reproduction space viewed in a second direction (a direction from above the listener L toward the listener L). In FIG. 4, which is an example, environmental sounds are output, for example, using speakers 2, 3, 4, and 5, with their respective output levels (LVa2, LVa3, LVa4, and LVa5) adjusted to distribute the sounds in the first range R1. Target sounds are output, for example, using speakers 3 and 4, with their respective output levels (LVo3 and LVo4) adjusted and panned to localize the sounds at predetermined positions.

[0097] As shown in Figs. 4 to 7, the rear range RB is a range behind the direction in which the head of the listener L is facing, assuming that the direction is forward. In other words, the rear range RB is a range behind the listener L. The rear range RB is also a range centered in a direction directly opposite to the direction in which the head of the listener L is facing, and extends toward the rear of the listener L. As an example, a case will be described where the head of the listener L is facing in the 0 o'clock direction.

[0098] As shown by the two dashed-dot lines in Fig. 4 and Fig. 7, the rear range RB is a range from the 4 o'clock direction to the 8 o'clock direction (i.e., a range of 120° in terms of angle) centered at the 6 o'clock direction, which is the direction directly opposite to the 0 o'clock direction. However, the rear range RB is not limited to this. The rear range RB is also determined based on the direction information acquired by the information acquisition unit 140. Note that, as shown in Figs. 4 to 6, when the direction in which the head of the listener L is facing changes, the rear range RB changes accordingly, but the first range R1, point P, and first direction D1 do not change as described above.

[0099] As described above, the correction processing unit determines whether the first range R1 and the point P are included in the rear range RB, which is a range behind the listener L and is determined based on the direction information. The specific positional relationship between the first range R1, the first direction D1, and the rear range RB will be described below.

[0100] First, a case where the correction processing unit determines that the first range R1 and the point P are included in the rear range RB (Yes in step S50) will be described with reference to FIGS. 4, 5 and 7. FIG.

[0101] When the head of listener L is facing in the 0 o'clock direction as shown in FIG. 4, rear range RB is the range from the 4 o'clock direction to the 8 o'clock direction. Furthermore, first range R1 related to the environmental sound is the range from the 3 o'clock direction to the 9 o'clock direction, and point P related to the target sound is a point in the 5 o'clock direction, which is an example of first direction D1. In other words, point P is included in first range R1, and a part of the first range R1 is included in rear range RB. More specifically, point P related to the target sound is included in first range R1 related to the environmental sound, and both point P and a part of the first range R1 are included in rear range RB. In this case, the correction processing unit determines that both first range R1 and point P are included in rear range RB.

[0102] Furthermore, the same is true even if the direction in which the head of the listener L is facing as shown in FIG. 5 moves more clockwise than in the case shown in FIG.

[0103] 7, as in FIG. 4, the direction in which the head of the listener L is facing is the 0 o'clock direction, and the rear range RB is a range from the 4 o'clock direction to the 8 o'clock direction. Note that here, an example is shown in which the first range R1 related to the environmental sound is a range narrower than the 4 o'clock direction to the 8 o'clock direction. Even in such a case, point P is included in the first range R1, and the entire first range R1 is included in the rear range RB. More specifically, point P related to the target sound is included in the first range R1 related to the environmental sound, and both point P and the entire first range R1 are included in the rear range RB. In this case, the correction processing unit determines that both the first range R1 and point P are included in the rear range RB.

[0104] In the cases shown in FIGS. 4, 5, and 7, the correction processing unit applies correction processing to at least one of the first audio signal and the second audio signal. Here, as an example, the correction processing unit applies correction processing to the first audio signal out of the first audio signal and the second audio signal (S60). In other words, the correction processing unit does not apply correction processing to the second audio signal. More specifically, the first correction processing unit 131 applies correction processing to the first audio signal, and the second correction processing unit 132 does not apply correction processing to the second audio signal. Step S60 is a correction processing step.

[0105] Here, the correction processing unit performs correction processing so that when the sound reproduction space is viewed from a predetermined direction, there is no overlap between the first range R1 and the point P. More specifically, the correction processing unit performs correction processing so that when the sound reproduction space is viewed from the predetermined direction, there is no overlap between the first range R1, the first direction D1, and the point P. The predetermined direction is, for example, the above-mentioned second direction.

[0106] In other words, when the sound reproduction space as shown in Figures 2 and 4 to 7 is viewed in the second direction, which is the direction from above the listener L toward the listener L, the correction processing unit performs correction processing so that there is no overlap between the first range R1 and the first direction D1 and point P.

[0107] For example, the correction processing unit performs correction processing so that at least one of the first range R1 in which the sound image of the environmental sound is localized and the position of point P in which the sound image of the target sound is localized is moved. This eliminates overlap between the first range R1 and the first direction D1 and point P. Here, "so that there is no overlap" has the same meaning as ensuring that the first direction D1 and point P are not included in the first range R1.

[0108] The first correction processing unit 131 outputs the corrected first audio signal to the mixing processing unit 150, and the second correction processing unit 132 outputs the uncorrected second audio signal to the mixing processing unit 150.

[0109] The mixing processing unit 150 mixes the first audio signal that has been corrected by the first correction processing unit 131 and the second audio signal that has not been corrected by the second correction processing unit 132, and outputs the mixed signal to a plurality of output channels (S70). As described above, the plurality of output channels refers to a plurality of speakers 1, 2, 3, 4, and 5. Step S70 is a mixing processing step.

[0110] Next, a case where the correction processing unit determines that the first range R1 and the first direction D1 are not included in the rear range RB (No in step S50) will be described with reference to FIG.

[0111] When the head of the listener L is facing in the 2 o'clock direction as shown in Fig. 6, the rear range RB is the range from the 6 o'clock direction to the 10 o'clock direction. Furthermore, the first range R1, point P, and first direction D1 remain unchanged from Figs. 4 and 5. In this case, the correction processing unit determines that point P is not included in the rear range RB. More specifically, the correction processing unit determines that at least one of the first range R1 and point P is not included in the rear range RB.

[0112] 6, the correction processing units do not perform correction processing on the first audio signal and the second audio signal (S80). The first correction processing unit 131 outputs the uncorrected first audio signal to the mixing processing unit 150, and the second correction processing unit 132 outputs the uncorrected second audio signal to the mixing processing unit 150.

[0113] The mixing processor 150 mixes the first audio signal and the second audio signal that have not been subjected to correction processing by the correction processor, and outputs the mixed signal to a plurality of speakers 1, 2, 3, 4, and 5, which are a plurality of output channels (S90).

[0114] As described above, in this embodiment, the sound reproduction method includes a signal acquisition step, an information acquisition step, a correction processing step, and a mixing processing step. The signal acquisition step acquires a first audio signal corresponding to an environmental sound reaching the listener L from a first range R1, which is a first angle range in the sound reproduction space, and a second audio signal corresponding to a target sound reaching the listener L from a point P in a first direction D1 in the sound reproduction space. The information acquisition step acquires directional information, which is information about a direction in which the head of the listener L is facing. The correction processing step performs correction processing when it is determined, based on the acquired directional information, that the first range R1 and the point P are included in the rear range RB, where the range behind the direction in which the head of the listener L is facing is defined as the forward direction. More specifically, the correction processing step performs correction processing on at least one of the acquired first audio signal and the acquired second audio signal so that there is no overlap between the first range R1 and the point P when the sound reproduction space is viewed in a predetermined direction. The mixing step mixes at least one of the first audio signal on which the correction process has been performed and the second audio signal on which the correction process has been performed, and outputs the mixed signal to an output channel.

[0115] As a result, when the first range R1 and the point P are included in the rear range RB, a correction process is performed so that there is no overlap between the first range R1 and the point P. This prevents the target sound, whose sound image is localized at the point P, from being buried in the environmental sound, whose sound image is localized in the first range R1, and makes it easier for the listener L to hear the target sound reaching the listener L from behind the listener L. In other words, a sound reproduction method is realized that can improve the perception level of the sound reaching the listener L from behind (the target sound in this embodiment).

[0116] The first range R1 is a range behind the reference direction determined by the positions of the five speakers 1, 2, 3, 4 and 5.

[0117] This makes it easier for the listener L to hear the target sound reaching the listener L from behind the listener L, even if the environmental sound reaches the listener L from a range behind the reference direction.

[0118] The predetermined direction is a second direction that is a direction from above the listener L toward the listener L.

[0119] As a result, when viewed from above the listener L, there is no overlap between the first range R1 and the point P. As a result, the listener L can easily hear the target sound reaching the listener L from behind the listener L. In other words, a sound reproduction method is realized that can improve the perception level of the target sound reaching the listener L from behind.

[0120] Furthermore, for example, the program according to the present embodiment may be a program for causing a computer to execute the above-described sound reproducing method.

[0121] This allows the computer to execute the above-described sound reproduction method in accordance with the program.

[0122] Here, first to fourth examples of the correction process performed by the correction processing unit in the first operational example will be described.

[0123] <Example 1> In the first example, the correction process is performed on the first audio signal, so that the first range R1 includes the second range R2 and the third range R3. In other words, the correction process is performed, so that the first range R1 is divided into the second range R2 and the third range R3. Furthermore, the environmental sound reaches the listener L from the second range R2 and the third range R3.

[0124] FIG. 8 is a diagram illustrating an example of correction processing according to the first example of the first operation example according to the present embodiment.

[0125] Fig. 8(a) is a schematic diagram showing an example of the first audio signal before the correction process according to the first example of the present embodiment is performed, and corresponds to Fig. 4. At this time, the correction process according to the first example is performed on the first audio signal in step S60.

[0126] Fig. 8(b) is a schematic diagram showing an example of the first audio signal after the correction process according to the first example of the present embodiment has been performed. Note that the two dashed dotted lines relating to the rear range RB are omitted in Fig. 8, and this also applies to Figs. 9 to 11 described later.

[0127] The correction process according to the first example will be described in detail below.

[0128] The first range R1 indicated by the corrected first audio signal includes a second range R2 and a third range R3.

[0129] The second range R2 is a second angle range when the sound reproduction space is viewed in a second direction. In addition, the second range R2 is, for example, a range from the 6 o'clock direction to the 9 o'clock direction (i.e., a range of 90 degrees in angle), but is not limited to this.

[0130] The third range R3 is a range of a third angle when the sound reproduction space is viewed in a second direction. The third angle is different from the second angle described above. In addition, the third range R3 is, for example, a range from the 3 o'clock direction to the 4 o'clock direction (i.e., a range of 30 degrees in angle), but is not limited to this. The third range R3 is a range different from the second range R2 and does not overlap with the second range R2. In other words, the second range R2 and the third range R3 are separated from each other.

[0131] Here, the environmental sound reaches the listener L from the entire area of ​​the second range R2 and the third range R3. In (b) of Fig. 8, the environmental sound is the sound that reaches the listener L from the entire area indicated by dots that represent the second range R2 and the third range R3. In other words, the environmental sound is, for example, the sound image of which is localized in the entire area indicated by dots in (b) of Fig. 8.

[0132] As described above, the first range R1 before correction processing is performed is the range from the 3 o'clock direction to the 9 o'clock direction. The second range R2 is the range from the 6 o'clock direction to the 9 o'clock direction, and the third range R3 is the range from the 3 o'clock direction to the 4 o'clock direction. Therefore, here, the second range R2 and the third range R3 are narrower than the first range R1 before correction processing is performed, that is, they are ranges that fall within the first range R1 before correction processing is performed.

[0133] Furthermore, point P indicating the target sound is a point in the 5 o'clock direction. Therefore, the second range R2 and the third range R3 are arranged to sandwich point P in the first direction D1. Furthermore, when the sound reproduction space is viewed in the second direction, the second range R2 does not overlap with point P, and the third range R3 does not overlap with point P. More specifically, when the sound reproduction space is viewed in the second direction, the second range R2 does not overlap with point P and the first direction D1, and the third range R3 does not overlap with point P and the first direction D1.

[0134] This correction process will be described in more detail below. In Fig. 8(b), for example, the environmental sound is output by adjusting the output levels (LVa21 and LVa31) of speakers 2 and 3, correcting the distribution of the environmental sound to the third range R3, and then output. Furthermore, for example, the environmental sound is output by adjusting the output levels (LVa41 and LVa51) of speakers 4 and 5, correcting the distribution of the environmental sound to the second range R2, and then output. In other words, by outputting the environmental sound at the adjusted output levels of speakers 3 and 4, the level of the environmental sound distributed in the range between the third range R3 and the second range R2 is adjusted to be reduced.

[0135] For example, the relational expressions showing the relationship between the angle (θ10) of the direction of the target sound to be localized, the angles (θ13 and θ14) of the direction in which speakers 3 and 4 are arranged, the output levels before correction (LVa2, LVa3, LVa4 and LVa5), the output levels after correction (LVa21, LVa31, LVa41 and LVa51), and a predetermined output level adjustment amount g0 are expressed as equations (1), (2), (3), (4), (5) and (6).

[0136] (1) g1=g0×|(θ13-θ10)| / |(θ13-θ14)| (2) LVa21=LVa2×(1+g1) (3) LVa31=LVa3×(-g1) (4) g2=g0×|(θ14-θ10)| / |(θ13-θ14)| (5) LVa41=LVa4×(-g2) (6) LVa51=LVa5×(1+g2)

[0137] The output level may be adjusted using equations (1), (2), (3), (4), (5), and (6). This is an example of adjusting the total output levels from multiple speakers 1, 2, 3, 4, and 5 to a constant value.

[0138] Alternatively, when headphones are used instead of the multiple speakers 1, 2, 3, 4, and 5, the following processing is performed. For example, based on the angle indicating the direction of the target sound to be localized, instead of convolving the head-related transfer function for the 4 o'clock direction where speaker 3 is located, a processing is performed to convolve the head-related transfer function for a direction shifted by a predetermined angle counterclockwise with the environmental sound, and instead of convolving the head-related transfer function for the 8 o'clock direction where speaker 4 is located, a processing is performed to convolve the head-related transfer function for a direction shifted by a predetermined angle clockwise with the environmental sound, thereby adjusting the angle of the head-related transfer function to be convolved with the environmental sound so that the environmental sound is distributed in the third range R3 and the second range R2 related to the environmental sound. In other words, the correction processing here is processing to adjust the angle corresponding to the head-related transfer function to be convolved with the first audio signal related to the environmental sound.

[0139] For example, the relational expressions showing the relationship between the angle (θ10) of the direction of the target sound to be localized, the angles (θ13 and θ14) of the direction in which speakers 3 and 4 are arranged, the angle of the corrected direction (θ23 and θ24), the angle adjustment amounts Δ3 and Δ4, and a predetermined coefficient α are expressed as equations (7), (8), (9), and (10). Note that the predetermined coefficient α is a coefficient by which the difference in angle between the direction of the target sound and the direction in which speakers 3 and 4 are arranged is multiplied.

[0140] (7) Δ3=α×(θ13-θ10) (8) θ23=θ13+Δ3 (9) Δ4=α×(θ14-θ10) (10) θ24=θ14+Δ4

[0141] The direction of the head-related transfer function to be convolved may be adjusted based on the angle of the direction corrected by equations (7), (8), (9), and (10).

[0142] In this way, by performing the correction process, the range in which the sound image of the environmental sound is localized is corrected from the first range R1 to the second range R2 and the third range R3.

[0143] Furthermore, the process by which the correction processing section performs this correction process will be described below.

[0144] Here, the first correction processing unit 131 performs correction processing on the first audio signal, and the second correction processing unit 132 does not perform correction processing on the second audio signal. The first correction processing unit 131 performs processing to convolve the first audio signal with a head-related transfer function so that the first range R1 includes the second range R2 and the third range R3, that is, so that the first range R1 is divided into the second range R2 and the third range R3. In other words, the first correction processing unit 131 performs the above correction processing by controlling the frequency characteristics of the first audio signal.

[0145] To summarize the above, in the first example, the first range R1 indicated by the corrected first audio signal includes a second range R2 that is a second angle range and a third range R3 that is a third angle range different from the second angle. The ambient sound reaches the listener L from the second range R2 and the third range R3. When the sound reproduction space is viewed in the second direction, the second range R2 does not overlap with point P, and the third range R3 does not overlap with point P.

[0146] As a result, the environmental sound reaches the listener L from the second range R2 and the third range R3, that is, from two ranges. This makes it possible to improve the perception level of the target sound reaching the listener L from behind, and realizes a sound reproduction method that allows the listener L to hear a wide range of environmental sound.

[0147] Also, as an example, the correction process is a process of adjusting the output level of at least one of the acquired first audio signal and the acquired second audio signal.

[0148] As another example, the correction process is a process of adjusting the output level of at least one of the acquired first audio signal and the acquired second audio signal. More specifically, the correction process is a process of adjusting the output level of each of a plurality of output channels to which at least one of the audio signals is output. In this case, the correction process adjusts the output levels of the first audio signal and the second audio signal for each of the plurality of output channels to which the first audio signal and the second audio signal are output.

[0149] As another example, the correction process is a process of adjusting the output level of each of the multiple output channels from which the second audio signal is output, based on the output level of the first audio signal corresponding to the environmental sound reaching the listener L from the first range R1. In this case, the output level of the second audio signal output from the multiple output channels is determined based on the output level of the first audio signal before the correction process is performed.

[0150] Also, as an example, the correction process is a process of adjusting an angle corresponding to a head-related transfer function convolved with at least one of the acquired first audio signal and the acquired second audio signal.

[0151] As another example, the correction process is a process of adjusting an angle corresponding to a head-related transfer function to be convolved with the second audio signal, based on an angle corresponding to a head-related transfer function to be convolved with the first audio signal so that the environmental sound represented by the first audio signal reaches the listener from the first range R1. In this case, an angle corresponding to a head-related transfer function related to the second audio signal output from the multiple output channels is determined based on the angle corresponding to the head-related transfer function related to the first audio signal before the correction process is performed.

[0152] These correction processes make it easier for the listener L to hear the target sound reaching the listener L from behind the listener L. In other words, a sound reproduction method is realized that can further improve the perceived level of the sound reaching the listener L from behind.

[0153] The above-described process for performing the correction process is one example. As another example, the correction processing unit may perform the correction process on at least one of the first audio signal and the second audio signal so as to change the speakers from which the environmental sound and the target sound are output. Furthermore, the correction processing unit may perform the correction process on the first audio signal so as to eliminate the volume of a portion of the environmental sound. This portion of the sound is a sound (environmental sound) whose sound image is localized in a range around point P within the first range R1 (for example, a range from 4 o'clock to 6 o'clock).

[0154] As a result, a correction process is performed so that the first range R1 includes the second range R2 and the third range R3, that is, so that the first range R1 is divided into the second range R2 and the third range R3. This realizes a sound reproduction method that can improve the perception level of the target sound arriving from behind the listener L and that allows the listener L to hear a wide range of environmental sounds.

[0155] <Example 2> In the first example, the first range R1 subjected to the correction process includes the second range R2 and the third range R3, but is not limited to this. In the second example, the first range R1 subjected to the correction process includes only the second range R2.

[0156] FIG. 9 is a diagram illustrating an example of correction processing according to the second example of the first operation example according to the present embodiment.

[0157] More specifically, (a) of Fig. 9 is a schematic diagram showing an example of the first audio signal before the correction process according to the second example of the present embodiment is performed, and corresponds to Fig. 4. At this time, the correction process according to the second example is performed on the first audio signal in step S60. (b) of Fig. 9 is a schematic diagram showing an example of the first audio signal after the correction process according to the second example of the present embodiment has been performed.

[0158] In the second example, the first range R1 to which the correction process has been performed includes only the second range R2 shown in the first example. That is, the point P in the first direction D1 does not have to be sandwiched between the second range R2 and the third range R3.

[0159] Even in such a case, the target sound, the sound image of which is localized at point P, is prevented from being buried in the environmental sound, the sound image of which is localized in the first range R1, and the listener L can easily hear the target sound reaching the listener L from behind the listener L. In other words, a sound reproduction method is realized that can improve the perception level of the target sound reaching the listener L from behind.

[0160] <Example 3> In the first example, the second range R2 is narrower than the first range R1 before the correction process is performed, but this is not limiting. In the third example, the second range R2 is a range that is expanded outward from the first range R1 before the correction process is performed.

[0161] FIG. 10 is a diagram illustrating an example of correction processing according to the third example of the first operation example according to the present embodiment.

[0162] More specifically, (a) of Fig. 10 is a schematic diagram showing an example of the first audio signal before the correction process according to the third example of the present embodiment is performed, and corresponds to Fig. 4. At this time, the correction process according to the third example is performed on the first audio signal in step S60. (b) of Fig. 10 is a schematic diagram showing an example of the first audio signal after the correction process according to the third example of the present embodiment has been performed.

[0163] In the third example, the first range R1 that has been subjected to the correction process includes only the second range R2.

[0164] The second range R2 is the range from the 6 o'clock direction to the 10 o'clock direction. Therefore, in this case, the second range R2 is a range wider than the first range R1 before the correction process is applied, that is, a range that is extended outward from the first range R1 before the correction process is applied.

[0165] Even in such a case, the target sound, the sound image of which is localized at point P, is prevented from being buried in the environmental sound, the sound image of which is localized in the first range R1, and the listener L can easily hear the target sound reaching the listener L from behind the listener L. In other words, a sound reproduction method is realized that can improve the perception level of the target sound reaching the listener L from behind.

[0166] <Example 4> Unlike the first to third examples, in the fourth example, the point P in the first direction D1 will be described as an area having a certain size.

[0167] In this case, "so that there is no overlap" in step S60 described in the first operational example means "so that the overlapping area is small."

[0168] 11 is a diagram illustrating an example of the correction process according to the fourth example of the first operation example according to the present embodiment. More specifically, (a) of FIG. 11 is a schematic diagram illustrating an example of the first audio signal before the correction process according to the fourth example of the present embodiment is performed, and corresponds to FIG. 4. At this time, the correction process according to the fourth example is performed on the first audio signal in step S60. (b) of FIG. 11 is a schematic diagram illustrating an example of the first audio signal after the correction process according to the fourth example of the present embodiment has been performed.

[0169] In the fourth example, the first range R1 that has been subjected to the correction process includes the second range R2 and the third range R3.

[0170] In (a) of Figure 11, when the sound reproduction space is viewed in the second direction, the entire area of ​​point P, which is a region with a certain size, overlaps with the first range R1, which is the range in which the sound image of the environmental sound is localized.

[0171] 11(b), after the correction process, when the sound reproduction space is viewed in the second direction, part of the area of ​​point P overlaps with the second range R2, and another part of the area of ​​point P overlaps with the third range R3. In other words, in FIG. 11(b), this part and this other part of the area of ​​point P overlap with the second range R2 and the third range R3, which are ranges in which the sound image of the environmental sound is localized.

[0172] That is, in the fourth example, the correction process reduces the area where the point P at which the sound image of the objective sound is localized and the range at which the sound image of the environmental sound is localized.

[0173] Even in such a case, the target sound, the sound image of which is localized at point P, is prevented from being buried in the environmental sound, the sound image of which is localized in the first range R1, and the listener L can easily hear the target sound reaching the listener L from behind the listener L. In other words, a sound reproduction method is realized that can improve the perception level of the target sound reaching the listener L from behind.

[0174] This correction process will now be described in detail.

[0175] For example, when the angle θP indicates a range based on the size of point P, which indicates the position of the target sound, the output level adjustment amounts g1 to g2 used to adjust the output level of this environmental sound may be adjusted using equations (11) and (12), which are relational equations showing the relationship between a predetermined output level adjustment amount g0 and the angle θP, which indicates a range based on the size of point P.

[0176] (11) g1=g0×|(θ13-(θ10-θP / 2))| / |(θ13-θ14)| (12) g2=g0×|(θ14-(θ10+θP / 2))| / |(θ13-θ14)|

[0177] That is, the output level adjustment amounts g1 and g2 may be adjusted based on the magnitude of θP using equations (11) and (12).

[0178] Alternatively, if headphones are used instead of multiple speakers 1, 2, 3, 4 and 5, then equations (13) and (14) are used and the following processing is performed:

[0179] (13) Δ3=α×(θ13-(θ10-θP / 2)) (14) Δ4=α×(θ14-(θ10+θP / 2))

[0180] That is, the angle adjustment amounts Δ3 and Δ4 may be adjusted based on the magnitude of θ P using equations (13) and (14).

[0181] In the first to fourth examples, the second audio signal is not subjected to correction processing, but this is not limiting. In other words, correction processing may be applied to both the first audio signal and the second audio signal.

[0182] [Example 2] Next, a description will be given of an operation example 2 of the sound reproducing method performed by the sound reproducing device 100. Fig. 12 is a flowchart of the operation example 2 of the sound reproducing device 100 according to this embodiment.

[0183] In Operation Example 2, steps S10 to S40 are the same as those in Operation Example 1. The correction process according to this example will be further described with reference to FIG.

[0184] Fig. 13 is a diagram illustrating an example of correction processing according to Operation Example 2 of this embodiment. Fig. 13 is a diagram of the sound reproduction space viewed in a third direction, which is a direction from the side of the listener L toward the listener L. Here, the side of the listener L refers to the left side of the listener L's face, but it may also refer to the right side. More specifically, the third direction refers to a direction from the left side of the listener L's face toward the listener L in parallel along the horizontal plane.

[0185] Fig. 13(a) is a schematic diagram showing an example of the first audio signal before the correction process of Operation Example 2 of the present embodiment is performed, and corresponds to Fig. 7. Fig. 13(b) is a schematic diagram showing an example of the first audio signal after the correction process of Operation Example 2 of the present embodiment is performed.

[0186] Here, the environmental sound and the target sound in the second operation example will be described.

[0187] 13(a), when the sound reproduction space is viewed in the third direction, the environmental sound represented by the first audio signal acquired by the first decoding unit 121 reaches the listener L from a first range R1 that is within a fourth angle A4 in the sound reproduction space. Similarly, when the sound reproduction space is viewed in the third direction, the target sound represented by the second audio signal acquired by the second decoding unit 122 reaches the listener L from a point P in a fourth direction D4 in the sound reproduction space.

[0188] Furthermore, the fourth angle A4 related to the environmental sound and the fourth direction D4 related to the objective sound will be described.

[0189] First, a horizontal plane at the height of the listener L's ears is defined as a first horizontal plane H1. A fourth angle A4 is the sum of a first elevation angle θ1 and a depression angle θ2 based on the first horizontal plane H1 and the listener L's ears. A fourth direction D4 is a direction in which the angle between the fourth direction D4 and the first horizontal plane H1 is θ3. In other words, the elevation angle of the fourth direction D4 based on the first horizontal plane H1 and the listener L's ears is θ3 (second elevation angle θ3). Note that here, the first elevation angle θ1 is greater than the second elevation angle θ3.

[0190] The environmental sound is the sound that reaches the listener L from the entire area of ​​the first range R1, that is, the entire area of ​​the range of the fourth angle A4 when the sound reproduction space is viewed in the third direction (the area marked with dots in FIG. 13). The environmental sound is, for example, the sound image of which is localized throughout the entire area marked with dots in FIG. 13.

[0191] In addition, in this operation example, point P is a point located in the fourth direction D4 and at a predetermined distance from the listener L when the sound reproduction space is viewed in the third direction, and is, for example, a black point shown in Figure 13.

[0192] The target sound is a sound whose sound image is localized at this black point (point P).

[0193] Here, the second operation example will be further described with reference to FIG. 12. After the process of step S40, the correction processing unit determines whether a predetermined condition is satisfied based on the acquired direction information. That is, the correction processing unit determines whether the first range R1 and the point P are included in the rear range RB and whether the fourth direction D4 is included in the fourth angle A4 based on the acquired direction information (S50a).

[0194] In this step S50a, first, the correction processing unit determines whether or not the first range R1 and point P are included in the rear range RB based on the acquired direction information. More specifically, the correction processing unit determines whether or not the first range R1 and point P are included in the rear range RB when the sound reproduction space is viewed in the second direction based on the acquired direction information, first information, and second information. In other words, the same process as step S50 in Operation Example 1 is performed.

[0195] Next, in step S50a, the correction processing unit determines whether or not the fourth direction D4 is included in the fourth angle A4 based on the acquired direction information. More specifically, the correction processing unit determines whether or not the fourth direction D4 is included in the fourth angle A4 when the sound reproduction space is viewed in the third direction based on the acquired direction information, the first information, and the second information.

[0196] Here, the determination made by the correction processor will be explained again with reference to (a) of Figure 13. Note that, since (a) of Figure 13 corresponds to Figure 7, it is determined that the first range R1 and point P are included in the rear range RB. Furthermore, since the first elevation angle θ1 is greater than the second elevation angle θ3 as described above, in the case shown in (a) of Figure 13, the correction processor determines that the fourth direction D4 is included in the fourth angle A4.

[0197] In the case shown in (a) of FIG. 13, the correction processing unit determines that the first range R1 and point P are included in the rear range RB, and that the fourth direction D4 is included in the fourth angle A4 (Yes in step S50a). In this case, the correction processing unit performs correction processing on at least one of the first audio signal and the second audio signal. Here, as an example, the correction processing unit performs correction processing on the first audio signal and the second audio signal (S60a). More specifically, the first correction processing unit 131 performs correction processing on the first audio signal, and the second correction processing unit 132 performs correction processing on the second audio signal.

[0198] The correction processing unit performs correction processing so that the first range R1 does not overlap with the point P when the sound reproduction space is viewed from a predetermined direction. Here, the predetermined direction is, for example, the third direction described above. Furthermore, the correction processing unit performs correction processing so that the fourth direction D4 does not overlap with the first range R1 when the sound reproduction space is viewed in the third direction. In other words, the correction processing unit performs correction processing so that the first range R1 does not overlap with the point P and the fourth direction D4 when the sound reproduction space is viewed in the third direction.

[0199] The result of the correction processing performed by the correction processing unit is shown in FIG. 13(b).

[0200] In this operation example, for example, the correction processing unit performs correction processing so that at least one of the first range R1 in which the sound image of the environmental sound is localized and the position of point P in which the sound image of the target sound is localized is moved. This eliminates overlap between the first range R1 and the fourth direction D4 and point P. Here, "so that there is no overlap" has the same meaning as ensuring that the first direction D1 and point P are not included in the first range R1.

[0201] As an example, the correction processing unit performs correction processing so that the first elevation angle θ1 decreases, the depression angle θ2 increases, and the second elevation angle θ3 increases. As shown in (b) of FIG. 13, when correction processing is performed, the first elevation angle θ1<the second elevation angle θ3. In other words, correction processing is performed so that the first range R1 moves further downward and the point P moves further upward. Here, downward refers to a direction approaching the floor surface F, and upward refers to a direction away from the floor surface F. As in the first example of Operation Example 1, the correction processing unit controls the first elevation angle θ1, the depression angle θ2, and the second elevation angle θ3 by performing processing to convolve the first audio signal and the second audio signal with a head-related transfer function.

[0202] The first correction processing unit 131 outputs the corrected first audio signal to the mixing processing unit 150, and the second correction processing unit 132 outputs the uncorrected second audio signal to the mixing processing unit 150.

[0203] The mixing processor 150 mixes the first and second audio signals corrected by the first and second correction processors 131 and 132, and outputs the mixed signals to a plurality of output channels (S70a).

[0204] In addition, if the correction processing unit determines that the first range R1 and point P are not included in the rear range RB and that the fourth direction D4 is not included in the fourth angle A4 (No in step S50a), processing of steps S80 and S90 is performed, as in operation example 1.

[0205] As described above, in this operation example, the predetermined direction is the third direction, which is the direction from the side of the listener L toward the listener L.

[0206] As a result, when viewed from the side of the listener L, there is no overlap between the first range R1 and the point P. As a result, the listener L can easily hear the target sound reaching the listener L from behind the listener L. In other words, a sound reproduction method is realized that can improve the perception level of the target sound reaching the listener L from behind.

[0207] Furthermore, in this operation example, when the sound reproduction space is viewed in a third direction, the environmental sound represented by the acquired first audio signal reaches the listener L from a first range R1, which is a fourth angle range in the sound reproduction space. When the sound reproduction space is viewed in the third direction, the target sound represented by the acquired second audio signal reaches the listener L from a point P in a fourth direction D4 in the sound reproduction space. If the correction processing unit determines that the fourth direction D4 is included in the fourth angle, the correction processing unit performs correction processing so that the fourth direction D4 and the first range R1 do not overlap when the sound reproduction space is viewed in the third direction. More specifically, the correction processing unit performs correction processing on at least one of the acquired first audio signal and the acquired second audio signal.

[0208] As a result, when viewed from the side of the listener L, there is no overlap between the first range R1 and point P, and there is no overlap between the first range R1 and the fourth direction D4. As a result, the listener L can easily hear the target sound reaching the listener L from behind the listener L. In other words, a sound reproduction method is realized that can improve the perception level of the target sound reaching the listener L from behind.

[0209] The correction process in the second operation example is not limited to the above.

[0210] For example, correction processing may be performed so that the first range R1 moves further upward and the point P moves further downward.

[0211] For example, correction processing may be performed so that the first range R1 remains unchanged and point P moves further downward or upward. In this case, the first correction processing unit 131 does not perform correction processing on the first audio signal, and the second correction processing unit 132 performs correction processing on the second audio signal. Alternatively, correction processing may be performed so that the first range R1 moves further downward or upward without changing point P. In this case, the first correction processing unit 131 performs correction processing on the first audio signal, and the second correction processing unit 132 does not perform correction processing on the second audio signal.

[0212] Even in such a case, when viewed from the side of the listener L, there is no overlap between the first range R1 and point P, and there is no overlap between the first range R1 and the fourth direction D4. In other words, a sound reproduction method is realized that can improve the perceived level of a target sound arriving from behind the listener L.

[0213] As another first example, the correction processing unit may perform the following process. This other first example is, for example, an example in which headphones are used instead of the multiple speakers 1, 2, 3, 4, and 5. Fig. 14 is a diagram illustrating another example of the correction process according to operation example 2 of the present embodiment. The target sound may be corrected, for example, by convolving a head-related transfer function from the elevation angle direction of the second elevation angle θ3a.

[0214] For the sake of explanation, the fourth angle A4 before correction is the sum of the first elevation angle θ1a and depression angle θ2a based on the first horizontal plane H1 and the ears of the listener L, and the fourth direction D4 before correction is the direction in which the angle between the fourth direction D4 and the first horizontal plane H1 is θ3a (second elevation angle θ3a).Furthermore, the fourth angle A4 after correction is the sum of the first elevation angle θ1b and depression angle θ2b based on the first horizontal plane H1 and the ears of the listener L, and the fourth direction D4 after correction is the direction in which the angle between the fourth direction D4 and the first horizontal plane H1 is θ3b (second elevation angle θ3b).

[0215] Furthermore, for example, the relational expressions showing the relationship between the angle adjustment amounts Δ5, Δ6, and Δ7 and the predetermined coefficient β are expressed as equations (15), (16), (17), (18), (19), and (20). Note that the predetermined coefficient β is a coefficient multiplied by the difference between the direction of the target sound and the first elevation angle θ1a, depression angle θ2a, and second elevation angle θ3a, which are values ​​before correction processing is performed.

[0216] (15) Δ5=β×(θ1a-θ3b) (16) θ1b=θ1a+Δ5 (17) Δ6=β×(θ2a-θ3b) (18) θ2b=θ2a+Δ7 (19) Δ7=β×(θ3a-θ3b) (20) θ3b=θ3a+Δ7

[0217] The direction of the head-related transfer function to be convolved may be adjusted based on the angle of the direction corrected by equations (15), (16), (17), (18), (19) and (20).

[0218] Furthermore, as another second example, the correction processing unit may perform the following process. In this other second example, for example, a plurality of speakers 1, 2, 3, 4, 5, 12, 13, 14, and 15 are used, and correction processing is performed by panning. FIG. 15 is a diagram illustrating another example of correction processing in operation example 2 according to this embodiment. Here, the sound reproducing device 100 processes a plurality of acquired audio signals and outputs them to a plurality of speakers 1, 2, 3, 4, 5, 12, 13, 14, and 15 in the sound reproduction space shown in FIG. 15, thereby allowing the listener L to hear sounds represented by the plurality of audio signals.

[0219] 15(a) and 15(b) are views of the sound reproduction space viewed in a second direction. FIG. 15(c) is a view of the sound reproduction space viewed in a third direction. FIG. 15(a) is a view showing the arrangement of multiple speakers 1, 2, 3, 4, and 5 at a height on a first horizontal plane H1, and FIG. 15(b) is a view showing the arrangement of multiple speakers 12, 13, 14, and 15 at a height on a second horizontal plane H2. The second horizontal plane H2 is a plane parallel to the first horizontal plane H1 and located higher than the first horizontal plane H1. Multiple speakers 12, 13, 14, and 15 are arranged on this second horizontal plane H2. For example, speaker 12 is arranged at 1 o'clock, speaker 13 at 4 o'clock, speaker 14 at 8 o'clock, and speaker 15 at 11 o'clock.

[0220] In this second example, the output levels of the multiple speakers 12, 13, 14, and 15 arranged on the second horizontal plane H2 are adjusted, and the target sound and the environmental sound are output by panning so as to be localized at predetermined positions. As a result, the target sound and the environmental sound can be localized as shown in (b) of FIG.

[0221] (Other embodiments) Although the sound reproduction device and sound reproduction method according to the aspects of the present disclosure have been described above based on the embodiments, the present disclosure is not limited to these embodiments. For example, the present disclosure may be embodied in another embodiment realized by any combination of the components described in this specification or by excluding some of the components. Furthermore, the present disclosure also includes various modifications that can be conceived by a person skilled in the art without departing from the spirit of the present disclosure, i.e., the meaning of the wording described in the claims.

[0222] The following embodiments may also be included within the scope of one or more aspects of the present disclosure.

[0223] (1) Some of the components constituting the above-mentioned sound reproducing device may be a computer system consisting of a microprocessor, ROM, RAM, hard disk unit, display unit, keyboard, mouse, etc. A computer program is stored in the RAM or hard disk unit. The microprocessor operates in accordance with the computer program to achieve its functions. Here, the computer program is composed of a combination of multiple instruction codes that indicate commands to a computer to achieve a predetermined function.

[0224] (2) Some of the components constituting the above-mentioned sound reproduction device and sound reproduction method may be configured as a single system LSI (Large Scale Integration). A system LSI is an ultra-multifunctional LSI manufactured by integrating multiple components on a single chip, and specifically, is a computer system configured including a microprocessor, ROM, RAM, etc. A computer program is stored in the RAM. The system LSI achieves its functions when the microprocessor operates in accordance with the computer program.

[0225] (3) Some of the components constituting the above-mentioned sound reproducing device may be composed of an IC card or a standalone module that can be attached to or detached from each device. The IC card or the module may be a computer system composed of a microprocessor, ROM, RAM, etc. The IC card or the module may include the above-mentioned ultra-multifunctional LSI. The IC card or the module achieves its functions when the microprocessor operates according to a computer program. The IC card or the module may be tamper-resistant.

[0226] (4) Furthermore, some of the components constituting the above-mentioned sound reproducing device may be the computer program or the digital signal recorded on a computer-readable recording medium, such as a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray (registered trademark) Disc), semiconductor memory, etc. Alternatively, they may be digital signals recorded on such recording media.

[0227] Furthermore, some of the components constituting the above-mentioned sound reproduction device may transmit the computer program or the digital signal via a telecommunications line, a wireless or wired communication line, a network such as the Internet, data broadcasting, etc.

[0228] (5) The present disclosure may be embodied as the methods described above, a computer program for implementing these methods on a computer, or a digital signal comprising the computer program.

[0229] (6) The present disclosure may also be a computer system having a microprocessor and a memory, the memory storing the computer program, and the microprocessor operating in accordance with the computer program.

[0230] (7) The program or the digital signal may also be implemented by another independent computer system by recording it on the recording medium and transferring it, or by transferring the program or the digital signal via the network, etc.

[0231] (8) The above-described embodiments and modifications may be combined with each other.

[0232] 2 and the like, an image linked to the sound output from the plurality of speakers 1, 2, 3, 4, and 5 may be presented to the listener L. In this case, for example, a display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel may be provided around the listener L, and the image may be presented on the display device. Alternatively, the image may be presented to the listener L by wearing a head-mounted display or the like.

[0233] 2, five speakers 1, 2, 3, 4, and 5 are provided, but the present invention is not limited to this. For example, a 5.1ch surround system may be used that is provided with the five speakers 1, 2, 3, 4, and 5 and a speaker corresponding to a subwoofer. Also, a multi-channel surround system that is provided with two speakers may be used, but the present invention is not limited to this.

[0234] In this embodiment, the listener L uses the sound reproducing device 100 while standing on the floor, but this is not limiting. The listener L may be seated on the floor or on a chair placed on the floor.

[0235] In this embodiment, the floor surface of the sound reproduction space is a surface parallel to a horizontal plane, but this is not limited to this. For example, the floor surface of the sound reproduction space may be an inclined surface parallel to a plane inclined from a horizontal plane. When the sound reproducing device 100 is used while the listener L is standing on the inclined surface, the second direction may be a direction from above the listener L toward the listener L along a direction perpendicular to the inclined surface. [Industrial Applicability]

[0236] The present disclosure is applicable to sound reproduction devices and sound reproduction methods, and is particularly applicable to stereophonic sound reproduction systems and the like. [Explanation of symbols]

[0237] 1, 2, 3, 4, 5, 12, 13, 14, 15 Speakers 100 Sound reproduction device 110 Signal processing section 121 First Decoding Unit 122 Second Decoding Unit 131 first correction processing unit 132 second correction processing section 140 Information Acquisition Department 150 Mixing Processing Unit 300 Head Sensor A4 4th angle D1 1st direction D4 4th direction F Floor H1 1st horizontal plane H2 2nd horizontal plane L listener P point R1 First range R2 Second range R3 Third range RB Rear Range

Claims

1. a signal acquisition step of acquiring a first audio signal corresponding to a first sound reaching a listener from a first area having an extension in a sound reproduction space, and a second audio signal corresponding to a second sound reaching the listener from a point in a first direction in the sound reproduction space; an information acquisition step of acquiring direction information which is information on the direction in which the head of the listener is facing; a correction processing step of performing a correction process on at least one of the acquired first audio signal and the acquired second audio signal when a range behind the direction in which the head of the listener is facing is defined as a forward direction and it is determined based on the acquired direction information that the first region and the point are included in the rear range. a mixing processing step of mixing the first audio signal and the second audio signal and outputting the mixed signal to an output channel, wherein, when a range behind a direction in which the head of the listener is facing is defined as forward, and it is determined based on the acquired direction information that at least a part of the first region and the point are included in the rear range, at least one of the first audio signal to be mixed and the second audio signal to be mixed is a signal to which the correction processing has been applied. Sound reproduction method.

2. The correction processing step performs the correction processing on at least one of the acquired first audio signal and the acquired second audio signal so that there is no overlap between the first region and the point when the sound reproduction space is viewed in a predetermined direction. The sound reproducing method according to claim 1 .

3. The first region is a region corresponding to a first angle with respect to the listener. The sound reproducing method according to claim 2.

4. The first region is a region behind the reference direction determined by the position of the output channel. The sound reproducing method according to claim 1 .

5. The predetermined direction is a second direction that is a direction from above the listener toward the listener. The sound reproducing method according to claim 2.

6. the first region indicated by the first audio signal that has been subjected to the correction process includes a second region that is a region of a second angle and a third region that is a region of a third angle that is different from the second angle; the first sound reaches the listener from the second area and the third area; When the sound reproduction space is viewed in the second direction, the second region and the point do not overlap, The third region and the point do not overlap. The sound reproducing method according to claim 5.

7. The predetermined direction is a third direction, which is a direction from the side of the listener toward the listener. The sound reproducing method according to claim 2.

8. When the sound reproduction space is viewed in a third direction, the first sound represented by the acquired first audio signal reaches the listener from the first region, which is a region of a fourth angle in the sound reproduction space; the second sound represented by the acquired second audio signal reaches the listener from the point in a fourth direction in the sound reproduction space; When it is determined that the fourth direction is included in the fourth angle, the correction processing step performs the correction processing on at least one of the acquired first audio signal and the acquired second audio signal so that there is no overlap between the fourth direction and the first area when the sound reproduction space is viewed in a third direction. The sound reproducing method according to claim 7.

9. The correction process is a process of adjusting an output level of at least one of the acquired first audio signal and the acquired second audio signal. The sound reproducing method according to any one of claims 1 to 8.

10. the mixing step mixes at least one of the first audio signal on which the correction process has been performed and the second audio signal on which the correction process has been performed, and outputs the mixed signal to the plurality of output channels; The correction process is a process of adjusting an output level of at least one of the acquired first audio signal and the acquired second audio signal in each of the plurality of output channels to which the at least one of the acquired first audio signal and the acquired second audio signal is output. The sound reproducing method according to any one of claims 1 to 9.

11. The correction process is a process of adjusting an output level of each of the plurality of output channels to which the second audio signal is output, based on an output level of the first audio signal corresponding to the first sound reaching the listener from the first region. The sound reproducing method according to claim 10.

12. The correction process is a process of adjusting an angle corresponding to a head-related transfer function convolved with at least one of the acquired first audio signal and the acquired second audio signal. The sound reproducing method according to any one of claims 1 to 9.

13. The correction process is a process of adjusting an angle corresponding to a head-related transfer function to be convoluted with the second audio signal, based on an angle corresponding to a head-related transfer function to be convoluted with the first audio signal so that the first sound represented by the first audio signal reaches the listener from the first region. The sound reproducing method according to claim 12.

14. A computer program for causing a computer to execute the sound reproducing method according to any one of claims 1 to 13.

15. a signal acquisition unit that acquires a first audio signal corresponding to a first sound that reaches a listener from a first area having an extension in a sound reproduction space, and a second audio signal corresponding to a second sound that reaches the listener from a point in a first direction in the sound reproduction space; an information acquisition unit that acquires direction information that is information about the direction in which the head of the listener is facing; a correction processing unit that, when a range behind a direction in which the head of the listener is facing is defined as a forward direction, performs a correction process on at least one of the acquired first audio signal and the acquired second audio signal when it is determined that the first region and the point are included in the rear range based on the acquired direction information; a mixing processing unit that mixes the first audio signal and the second audio signal and outputs the mixed signal to an output channel, and when a range behind the direction in which the head of the listener is facing is defined as the forward direction, and the mixing processing unit determines, based on the acquired direction information, that at least a part of the first region and the point are included in the rear range, at least one of the first audio signal to be mixed and the second audio signal to be mixed is a signal that has been subjected to the correction processing. Sound reproduction device.

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