Information processing method, program, and sound reproducing device

Abstract

This information processing method comprises: calculating, from sound information including information pertaining to predetermined sound and information pertaining to a predetermined direction at each point on a time axis, an angular amount of variation in the predetermined direction on the time axis; selecting, on the basis of the information pertaining to the predetermined direction, a three-dimensional acoustic filter for allowing an input sound being input to be perceived as sound from an incoming direction, from a plurality of three-dimensional acoustic filters which are a plurality of candidate three-dimensional acoustic filters prepared for each incoming direction; and generating an output signal by inputting the information pertaining to the predetermined sound into the selected three-dimensional acoustic filter. In the selection of the three-dimensional acoustic filter, when the calculated angular amount of variation in the predetermined direction is less than a threshold value, the three-dimensional acoustic filter is selected so that the predetermined sound is perceived by a user in a more emphasized manner than when the angular amount of variation in the predetermined direction is greater than or equal to the threshold value.

Description

[Technical field]

[0001] The present disclosure relates to an audio reproduction device, and an information processing method and program related to the audio reproduction device. [Background technology]

[0002] Conventionally, there is known a technology relating to sound reproduction that allows a user to perceive three-dimensional sound by controlling the position of a sound image, which is a sensory sound source object, in a virtual three-dimensional space (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-18620 A Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, when a user is made to perceive a sound as a stereoscopic sound in a three-dimensional sound field, a sound that is difficult for the user to perceive may be generated. In the information processing method in the conventional sound reproducing device, etc., there are cases where appropriate processing is not performed for such a sound that is difficult to perceive.

[0005] In view of the above, an object of the present disclosure is to provide an information processing method and the like that allows a user to more appropriately perceive three-dimensional sound. [Means for solving the problem]

[0006] An information processing method according to one aspect of the present disclosure is an information processing method for generating an output sound signal for causing a user to perceive a predetermined sound in a time series as a sound arriving from a direction of arrival in a three-dimensional sound field corresponding to a predetermined direction from sound information including information about a predetermined sound and information about a predetermined direction at each point on a time axis, the method calculating an angle amount of variation in the predetermined direction on the time axis, and selecting a stereophonic filter that causes an input sound to be perceived as a sound from the direction of arrival based on the information about the predetermined direction from among a plurality of candidate stereophonic filters prepared for each direction of arrival, inputting information about the predetermined sound to the selected stereophonic filter to generate the output signal, and in selecting the stereophonic filter, when the calculated angle amount of variation in the predetermined direction is smaller than a threshold value, selecting the stereophonic filter so that the predetermined sound is more emphasized and perceived by the user than when the angle amount of variation in the predetermined direction is equal to or greater than the threshold value.

[0007] Moreover, an audio reproduction device according to one aspect of the present disclosure is an audio reproduction device that generates and reproduces an output sound signal for causing a user to perceive a predetermined sound as a sound arriving from a direction of arrival in a three-dimensional sound field corresponding to a predetermined direction, from sound information including information about a predetermined sound and information about a predetermined direction at each point on a time axis, and that includes an acquisition unit that acquires the sound information; a filter selection unit that calculates an angle amount of fluctuation in the predetermined direction on the time axis and selects a stereophonic filter that causes an input sound to be perceived as a sound from the direction of arrival based on the information about the predetermined direction, from among a plurality of candidate stereophonic filters prepared for each direction of arrival; an output sound generation unit that inputs the information about the predetermined sound as the input sound to the selected stereophonic filter to generate the output sound signal; and an output unit that outputs sound based on the generated output sound signal, and the filter selection unit selects the stereophonic filter so that, when the calculated angle amount of fluctuation in the predetermined direction is smaller than a threshold value, the predetermined sound is more emphasized and perceived by the user than when the angle amount of fluctuation in the predetermined direction is equal to or greater than the threshold value.

[0008] Furthermore, one aspect of the present disclosure can also be realized as a program for causing a computer to execute the above-described sound reproducing method.

[0009] In addition, these comprehensive or specific aspects may be realized by 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 by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0010] According to the present disclosure, it is possible to allow a user to perceive stereoscopic sound more appropriately. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a use example of a sound reproducing device according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing a functional configuration of the sound reproducing device according to the embodiment. [Diagram 3] FIG. 3 is a block diagram illustrating a functional configuration of an acquisition unit according to the embodiment. [Figure 4] FIG. 4 is a block diagram illustrating a functional configuration of a filter selection unit according to the embodiment. [Diagram 5] FIG. 5 is a block diagram illustrating a functional configuration of an output sound generating unit according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing the operation of the sound reproducing device according to the embodiment. [Figure 7] FIG. 7 is a first diagram illustrating the arrival direction of a predetermined sound by a selected stereophonic filter according to the embodiment. [Figure 8] FIG. 8 is a second diagram illustrating the arrival direction of a predetermined sound by a selected stereophonic filter according to the embodiment. [Figure 9]FIG. 9 is a third diagram illustrating the arrival direction of a predetermined sound by a selected stereophonic filter according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (Knowledge on which the disclosure is based) Conventionally, there is known a technology related to sound reproduction for making a user perceive a three-dimensional sound by controlling the position of a sound image, which is a sound source object sensed by the user, in a virtual three-dimensional space (hereinafter, sometimes referred to as a three-dimensional sound field) (see, for example, Patent Document 1). By localizing a sound image at a predetermined position in the virtual three-dimensional space, the user can perceive the sound as if it were coming from a direction parallel to a line connecting the predetermined position and the user (i.e., a predetermined direction). In order to localize a sound image at a predetermined position in the virtual three-dimensional space in this way, for example, a calculation process is required to generate a time difference in arrival of the sound between both ears and a level difference (or sound pressure difference) between both ears that is perceived as a three-dimensional sound for the collected sound.

[0013] As an example of such a calculation process, a process of convolving a head-related transfer function for perceiving a sound as coming from a specific direction with a signal of a target sound is known. By carrying out the convolution process of the head-related transfer function with higher resolution, the sense of realism experienced by the user is improved. On the other hand, it is known that in the convolution of the head-related transfer function, fluctuations in the time domain of the sound arrival direction are difficult to perceive. For this reason, a user may mistakenly perceive a sound with a slight fluctuation in the time domain as not fluctuating.

[0014] In recent years, there has been active development of technology related to virtual reality (VR). In virtual reality, the position of the virtual three-dimensional space does not follow the user's movement, and the main focus is on allowing the user to experience it as if he or she were moving in the virtual space. In particular, attempts have been made to enhance the sense of realism by incorporating auditory elements into visual elements in this virtual reality technology. For example, when a sound image is localized in front of a user, if the user turns to the right, the sound image moves to the left of the user, and if the user turns to the left, the sound image moves to the right of the user. In this way, it becomes necessary to move the localization position of the sound image in the virtual space in the opposite direction to the user's movement in response to the user's movement. Such processing is performed by applying a stereophonic filter to the original sound information.

[0015] In view of the above, the present disclosure implements more appropriate calculation processing to improve the perceptibility of sounds with slight fluctuations in the time domain while utilizing a stereophonic filter that allows a user to perceive a sound as coming from a specific direction in a three-dimensional sound field. The present disclosure aims to provide an information processing method and the like that allows a user to perceive a stereophonic sound by this appropriate calculation processing.

[0016] More specifically, an information processing method according to one aspect of the present disclosure is an information processing method for generating an output sound signal that allows a user to perceive a specific sound in a time series as a sound arriving from an arrival direction in a three-dimensional sound field corresponding to a specific direction, from sound information including information about a specific sound and information about a specific direction at each point on a time axis, the method calculates an angle amount of variation in the specific direction on the time axis, and selects a stereophonic filter that causes an input sound to be perceived as a sound from the arrival direction based on the information about the specific direction, from among a plurality of candidate stereophonic filters, the stereophonic filter being prepared for each arrival direction, and inputting information about the specific sound to the selected stereophonic filter to generate an output signal. In selecting the stereophonic filter, a stereophonic filter is selected so that when the calculated angle amount of variation in the specific direction is smaller than a threshold value, the specific sound is more emphasized and perceived by the user than when the angle amount of variation in the specific direction is equal to or greater than the threshold value.

[0017] According to this information processing method, when the calculated angle of the change in the predetermined direction is smaller than a threshold value, that is, when the predetermined sound includes a minute change in the arrival direction that is difficult for the user to perceive, the predetermined sound can be emphasized and perceived by the user. Since the user's attention is directed to the predetermined sound, the minute change in the arrival direction of the predetermined sound can be more appropriately perceived by the user.

[0018] Also, for example, in selecting a stereophonic filter, when the calculated angular amount of fluctuation in a specified direction is smaller than a threshold value, a stereophonic filter may be selected so that the angular amount of fluctuation in the arrival direction perceived by the output sound signal when using the selected stereophonic filter is greater than the angular amount of fluctuation in the arrival direction perceived by the output sound signal when using a stereophonic filter selected when the calculated angular amount of fluctuation in a specified direction is equal to or greater than the threshold value.

[0019] According to this, compared to the case of applying a stereophonic filter that is selected when the predetermined sound has an angle of variation equal to or greater than a threshold, that is, a stereophonic filter that generates an output sound signal so that the angle of variation is set in advance in the content, a stereophonic filter can be selected so that the angle of variation is large in order to emphasize the predetermined sound. As a result, the output sound signal expands the angle of variation, and the predetermined sound is perceived as being emphasized.

[0020] Also, for example, when selecting a stereophonic filter, the stereophonic filter may be selected such that the smaller the calculated angle of variation in a specific direction, the larger the angle of variation in the arrival direction perceived by the output sound signal when the selected stereophonic filter is used.

[0021] According to this, in order to emphasize the predetermined sound, a stereophonic filter can be selected so that the angle of the fluctuation is larger than that of the predetermined sound, in other words, in comparison with the case of applying a stereophonic filter that is selected when the predetermined sound has an angle of fluctuation equal to or larger than a threshold value, that is, a stereophonic filter that generates an output sound signal so that the angle of the fluctuation is set in advance in the content. As a result, the predetermined sound is perceived as being emphasized by expanding the angle of the fluctuation by the output sound signal. At this time, the smaller the angle of the fluctuation in the sound information, the larger the angle of the fluctuation of the sound in the output sound signal, so that the predetermined sound whose fluctuation is difficult to perceive due to its small fluctuation in the original content is presented to the user with an emphasis so that it is more easily perceivable.

[0022] Also, for example, when the calculated angle amount of fluctuation in a specified direction is smaller than a threshold value, when the selected stereophonic filter is used, the smaller the angle amount of fluctuation in a specified direction in the sound information, the larger the expansion coefficient α (α>1) is multiplied, thereby expanding the angle amount of fluctuation in the arrival direction on the time axis of the output sound signal, and the relationship between the angle amount of fluctuation in the specified direction and the expansion coefficient α may be nonlinear.

[0023] According to this, the smaller the angle of the fluctuation in the sound information, the larger the angle of the sound fluctuation in the output sound signal, so that the predetermined sound whose fluctuation is small and therefore difficult to perceive in the original content is emphasized and presented to the user so that it is more easily perceivable. By multiplying by the expansion coefficient α, the relationship between the angle of the fluctuation in the predetermined direction and the arrival direction of the predetermined sound in the output sound information becomes nonlinear, so that the smaller the fluctuation of the predetermined sound, the more prominent the emphasis effect becomes.

[0024] Also, for example, in selecting a stereophonic filter, when a specified direction is on the front side of a virtual boundary surface that divides the user's head into front and back, and the calculated angle amount of fluctuation in the specified direction is smaller than a threshold value, a stereophonic filter may be selected so that the angle amount of fluctuation in the arrival direction on the time axis when the selected stereophonic filter is used is greater than the angle amount of fluctuation in the arrival direction on the time axis when the selected stereophonic filter is used when the specified direction is on the rear side of the boundary surface and the calculated angle amount of fluctuation in the specified direction is smaller than a threshold value.

[0025] This allows the emphasis effect to be greater on the rear side of the boundary surface, where it is difficult to sense changes in the arrival direction, than on the front side of the boundary surface.

[0026] Also, for example, when selecting a stereophonic filter, the stereophonic filter may be selected so that the direction of arrival perceived by the output sound signal when the selected stereophonic filter is used vibrates on the time axis compared to a specified direction in the sound information.

[0027] According to this, a predetermined sound whose arrival direction oscillates can be presented to a user in the output sound information. Since the arrival direction oscillates on the time axis, the user can easily perceive the predetermined sound compared to other sounds, which has the effect of making the user more easily perceive the fluctuation of the predetermined sound.

[0028] Furthermore, for example, when a selected stereophonic filter is used, the direction of arrival at the Nth (N is an integer equal to or greater than 2) point in time on the time axis of the output sound signal may be calculated by multiplying the difference value between a predetermined direction on the sound information corresponding to the (N-1)th point in time on the time axis of the output sound signal and a predetermined direction on the sound information corresponding to the Nth point in time by a numerical value at the corresponding point in an oscillatory function whose numerical value oscillates on the time axis, and adding the multiplied difference value to the predetermined direction on the sound information corresponding to the (N-1)th point in time.

[0029] According to this, a predetermined sound whose arrival direction oscillates can be presented to a user in the output sound information. Since the arrival direction oscillates on the time axis, the user can easily perceive the predetermined sound compared to other sounds, which has the effect of making the user more easily perceive the fluctuation of the predetermined sound.

[0030] Also, for example, in selecting a stereophonic filter, when the calculated angular amount of fluctuation in a specified direction is smaller than a threshold value, a stereophonic filter may be selected so that the amount of change in sound pressure of a specified sound on the time axis perceived by the output sound signal when using the selected stereophonic filter is greater than the amount of change in sound pressure of a specified sound perceived by the output sound signal when using a stereophonic filter selected when the calculated angular amount of fluctuation in a specified direction is equal to or greater than the threshold value.

[0031] According to this, compared to the case of applying a stereophonic filter that is selected when the predetermined sound has an angle of variation equal to or greater than a threshold, that is, a stereophonic filter that generates an output sound signal so as to have an angle of variation preset in the content, a stereophonic filter can be selected so as to increase the amount of change in sound pressure in order to emphasize the predetermined sound more. As a result, the amount of change in sound pressure is amplified by the output sound signal, and the predetermined sound is perceived as being emphasized.

[0032] Also, for example, an information processing method may be provided for generating an output sound signal for allowing a user to perceive a specific sound in a time series as a sound arriving from an arrival direction in a three-dimensional sound field corresponding to a specific direction from sound information including information about a specific sound and information about a specific direction at each point on a time axis, the method calculating an angle amount of variation in the specific direction on the time axis, and correcting the information about the specific direction so that the specific sound is perceived by the user with more emphasis when the calculated angle amount of variation in the specific direction is smaller than a threshold value compared to when the angle amount of variation in the specific direction is equal to or greater than the threshold value, and inputting the information about the specific sound to a stereophonic filter selected from a plurality of candidate stereophonic filters prepared for each arrival direction based on the information about the specific direction after the correction to generate an output signal.

[0033] According to this, when the calculated angle amount of the change in the predetermined direction is smaller than the threshold value, that is, when the predetermined sound includes a minute change in the arrival direction that is difficult for the user to sense, the predetermined sound can be emphasized and perceived by the user. For this reason, by correcting the information on the predetermined direction included in the sound information, the stereophonic filter selected thereafter can be made to be a stereophonic filter that emphasizes the predetermined sound and makes the user perceive it. As a result, the user's attention is directed to the predetermined sound, so that the minute change in the arrival direction of the predetermined sound can be more appropriately perceived by the user.

[0034] Moreover, a program according to one aspect of the present disclosure is a program for causing a computer to execute the information processing method described above.

[0035] According to this, it is possible to achieve the same effect as the above-described information processing method using a computer.

[0036] Moreover, an audio reproduction device according to one aspect of the present disclosure is an audio reproduction device that generates and reproduces an output sound signal for causing a user to perceive a specific sound as a sound arriving from an arrival direction in a three-dimensional sound field corresponding to a specific direction, from sound information including information about a specific sound and information about a specific direction at each point on a time axis, and includes an acquisition unit that acquires sound information; a filter selection unit that calculates an angle amount of fluctuation in the specific direction on the time axis and selects a stereophonic filter that causes an input sound to be perceived as a sound from the arrival direction based on the information about the specific direction, from among a plurality of candidate stereophonic filters prepared for each arrival direction; an output sound generation unit that inputs the information about the specific sound as input sound to the selected stereophonic filter to generate an output sound signal; and an output unit that outputs sound based on the generated output sound signal, and the filter selection unit selects a stereophonic filter so that the specific sound is more emphasized and perceived by the user when the calculated angle amount of fluctuation in the specific direction is smaller than a threshold value, compared to when the angle amount of fluctuation in the specific direction is equal to or greater than the threshold value.

[0037] According to this, it is possible to achieve the same effect as the information processing method described above.

[0038] Furthermore, these comprehensive or specific aspects may be realized in 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 in any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0039] Hereinafter, the embodiments will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement and connection forms of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, components that are not described in the independent claims are described as optional components. Note that each figure is a schematic diagram and is not necessarily illustrated strictly. In addition, in each figure, the same reference numerals are given to substantially the same configurations, and duplicated descriptions may be omitted or simplified.

[0040] In the following description, ordinal numbers such as first, second, and third may be attached to elements. These ordinal numbers are attached to elements in order to identify the elements and do not necessarily correspond to a meaningful order. These ordinal numbers may be rearranged, newly added, or removed as appropriate.

[0041] (Embodiment) [overview] First, an overview of the sound reproducing device according to the embodiment will be described. Fig. 1 is a schematic diagram showing a use example of the sound reproducing device according to the embodiment. Fig. 1 shows a user 99 using the sound reproducing device 100.

[0042] The sound reproducing device 100 shown in FIG. 1 is used simultaneously with the stereoscopic video reproducing device 200. By simultaneously viewing stereoscopic images and stereoscopic sounds, the images enhance the auditory realism and the sounds enhance the visual realism, respectively, allowing the user to experience the images and sounds as if they were at the scene where they were taken. For example, when an image (moving image) of people talking is displayed, it is known that even if the position of the sound image of the conversation sound is not aligned with the mouth of the person, the user 99 perceives the conversation sound as coming from the mouth of the person. In this way, the position of the sound image is corrected by visual information, and the sense of realism can be enhanced by combining the image and sound.

[0043] The three-dimensional video reproduction device 200 is an image display device worn on the head of the user 99. Therefore, the three-dimensional video reproduction device 200 moves integrally with the head of the user 99. For example, the three-dimensional video reproduction device 200 is a glasses-type device supported by the ears and nose of the user 99, as shown in the figure.

[0044] The stereoscopic video reproduction device 200 changes the image displayed in response to the movement of the user 99's head, thereby making the user 99 perceive the movement of his / her head in the three-dimensional image space. In other words, when an object in the three-dimensional image space is located in front of the user 99, when the user 99 turns to the right, the object moves to the left of the user 99, and when the user 99 turns to the left, the object moves to the right of the user. In this way, the stereoscopic video reproduction device 200 moves the three-dimensional image space in the opposite direction to the movement of the user 99 in response to the movement of the user 99.

[0045] The stereoscopic video reproduction device 200 displays two images with a parallax difference to each of the left and right eyes of the user 99. The user 99 can perceive the three-dimensional position of an object on the image based on the parallax difference between the displayed images. Note that when the user 99 uses the audio reproduction device 100 with his / her eyes closed, for example, when using the audio reproduction device 100 to reproduce healing sounds for sleep induction, the stereoscopic video reproduction device 200 does not need to be used at the same time. In other words, the stereoscopic video reproduction device 200 is not an essential component of the present disclosure.

[0046] The sound reproducing device 100 is a sound presentation device that is worn on the head of the user 99. Therefore, the sound reproducing device 100 moves integrally with the head of the user 99. For example, the sound reproducing device 100 in this embodiment is a so-called over-ear headphone type device. There is no particular limitation on the form of the sound reproducing device 100, and it may be, for example, two earplug-type devices that are independently worn on the left and right ears of the user 99. These two devices communicate with each other to present sounds for the right ear and the left ear in a synchronized manner.

[0047] The sound reproducing device 100 changes the sound presented in response to the movement of the head of the user 99, thereby making the user 99 perceive as if the user 99 is moving his / her head within the three-dimensional sound field. For this reason, as described above, the sound reproducing device 100 moves the three-dimensional sound field in the opposite direction to the movement of the user 99.

[0048] Here, it is known that when the change in the time domain (also referred to as the fluctuation on the time axis) of the sound image presented to the user becomes small, the user 99 becomes ambiguous in distinguishing the movement of the sound image in the three-dimensional sound field. The sound reproducing device 100 according to this embodiment can make the user 99 perceive that there is movement in the sound image by correcting the sound presented by information processing so as to complement this phenomenon. That is, the sound reproducing device 100 acquires the amount of movement of the sound image, and when the acquired amount of movement is smaller than a threshold value, the user 99 perceives a specific sound in the three-dimensional sound field with greater emphasis.

[0049] This threshold is a value related to the amount of movement that the user 99 cannot grasp, and is therefore a unique threshold for each user 99. Therefore, this threshold may be set to a value obtained experimentally or empirically. A generalized threshold based on statistics of multiple users 99 may also be applied. The amount of movement here refers to the amount of fluctuation in the direction from which a specific sound comes over an infinitesimal period of time, and is the amount of change in angle per infinitesimal period of time in the specific direction as seen by the user 99. In other words, the amount of movement is expressed by the maximum value of the angle between the directions from which two specific sounds come that correspond to each of two time points between the first time point and the second time point.

[0050] [composition] Next, the configuration of the sound reproducing device 100 according to the present embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the functional configuration of the sound reproducing device according to the embodiment.

[0051] As shown in FIG. 2, the sound reproducing device 100 according to this embodiment includes a processing module 101, a communication module 102, a detector 103, and a driver 104.

[0052] The processing module 101 is an arithmetic device for performing various signal processing in the sound reproduction device 100. The processing module 101 includes, for example, a processor and a memory, and performs various functions by the processor executing a program stored in the memory. The processing module 101 includes an acquisition unit 111, a filter selection unit 121, an output sound generation unit 131, and a signal output unit 141. Details of each functional unit of the processing module 101 will be described below together with details of the configuration other than the processing module 101.

[0053] The communication module 102 is an interface device for accepting input of sound information to the sound reproducing device 100. The communication module 102 includes, for example, an antenna and a signal converter, and receives sound information from an external device by wireless communication. More specifically, the communication module 102 receives a wireless signal indicating sound information converted into a format for wireless communication using the antenna, and reconverts the wireless signal into sound information using the signal converter. In this way, the sound reproducing device 100 acquires sound information from an external device by wireless communication. The sound information acquired by the communication module 102 is acquired by the acquisition unit 111. In this way, the sound information is input to the processing module 101. Note that the communication between the sound reproducing device 100 and the external device may be performed by wired communication.

[0054] The sound information acquired by the sound reproducing device 100 is encoded in a predetermined format such as MPEG-H 3D Audio (ISO / IEC 23008-3). As an example, the encoded sound information includes information about a predetermined sound reproduced by the sound reproducing device 100 and information about a localization position when the sound image of the sound is localized at a predetermined position in a three-dimensional sound field (i.e., the sound is perceived as coming from a predetermined direction), i.e., information about the predetermined direction. For example, the sound information includes information about a plurality of sounds including a first predetermined sound and a second predetermined sound, and the sound images are localized so that the sound images when the respective sounds are reproduced are perceived as coming from different directions in the three-dimensional sound field.

[0055] This stereoscopic sound can improve the sense of realism of the content being viewed, for example, together with the image viewed using the stereoscopic video reproducing device 200. The sound information may include only information about the predetermined sound. In this case, information about the predetermined direction may be acquired separately. As described above, the sound information includes the first sound information about the first predetermined sound and the second sound information about the second predetermined sound, but a plurality of pieces of sound information including these separately may be acquired and simultaneously reproduced to localize the sound image at different positions in the three-dimensional sound field. In this way, there is no particular limitation on the form of the input sound information, and it is sufficient that the sound reproducing device 100 is provided with an acquisition unit 111 that corresponds to various forms of sound information.

[0056] Here, an example of the acquisition unit 111 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing a functional configuration of the acquisition unit according to the embodiment. As shown in Fig. 3, the acquisition unit 111 in the present embodiment includes, for example, an encoded sound information input unit 112, a decode processing unit 113, and a sensing information input unit 114.

[0057] The encoded sound information input unit 112 is a processing unit to which the encoded (in other words, encoded) sound information acquired by the acquisition unit 111 is input. The encoded sound information input unit 112 outputs the input sound information to the decoding processing unit 113. The decoding processing unit 113 is a processing unit that decodes (in other words, decodes) the sound information output from the encoded sound information input unit 112 to generate information about a specific sound and information about a specific direction included in the sound information in a format used for subsequent processing. The sensing information input unit 114 will be described below together with the functions of the detector 103.

[0058] The detector 103 is a device for detecting the moving speed of the head of the user 99. The detector 103 is configured by combining various sensors used for detecting movement, such as a gyro sensor and an acceleration sensor. In this embodiment, the detector 103 is built in the sound reproducing device 100, but may be built in an external device, such as a stereoscopic image reproducing device 200 that operates in response to the movement of the head of the user 99 in the same manner as the sound reproducing device 100. In this case, the detector 103 does not need to be included in the sound reproducing device 100. In addition, the detector 103 may detect the movement of the user 99 by capturing an image of the head movement of the user 99 using an external imaging device or the like and processing the captured image.

[0059] The detector 103 is, for example, fixed integrally to the housing of the sound reproducing device 100 and detects the speed of movement of the housing. After the sound reproducing device 100 including the housing is worn by the user 99, it moves integrally with the head of the user 99, and as a result, the detector 103 can detect the speed of movement of the head of the user 99.

[0060] For example, the detector 103 may detect an amount of rotation about at least one of three mutually orthogonal axes in a three-dimensional space as a rotation axis, as the amount of movement of the head of the user 99, or may detect an amount of displacement about at least one of the above three axes as a displacement direction. Furthermore, the detector 103 may detect both the amount of rotation and the amount of displacement as the amount of movement of the head of the user 99.

[0061] The sensing information input unit 114 acquires the movement speed of the head of the user 99 from the detector 103. More specifically, the sensing information input unit 114 acquires the amount of head movement of the user 99 detected by the detector 103 per unit time as the movement speed. In this way, the sensing information input unit 114 acquires at least one of the rotation speed and the displacement speed from the detector 103. The amount of head movement of the user 99 acquired here is used to determine the coordinates and the orientation of the user 99 in the three-dimensional sound field. In the sound reproducing device 100, the relative position of the sound image is determined based on the determined coordinates and orientation of the user 99, and the sound is reproduced. Specifically, the above functions are realized by the filter selection unit 121 and the output sound generation unit 131.

[0062] The filter selection unit 121 is a processing unit that determines, based on the determined coordinates and orientation of the user 99, from which direction in the three-dimensional sound field the user 99 will perceive the predetermined sound as coming from, and selects a stereophonic filter to be applied to the predetermined sound. The stereophonic filter is a function filter that convolves a specific head-related transfer function with the input predetermined sound, thereby making the user 99 perceive the predetermined sound as coming from a specific direction based on the specific head-related transfer function. In other words, by inputting the predetermined sound (or information on the predetermined sound) to the stereophonic filter, a sound pressure difference, a time difference, a phase difference, and the like are generated between the left and right sound signals of the predetermined sound, and a sound signal that can reproduce the predetermined sound with a controlled arrival direction can be output.

[0063] A plurality of stereophonic filters that are candidates for selection are prepared in advance, for example, by adjusting them for each user 99 .

[0064] Here, an example of the filter selection unit 121 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing a functional configuration of the filter selection unit according to the embodiment. As shown in Fig. 4, the filter selection unit 121 in the present embodiment includes, for example, a filter storage unit 122, a fluctuation angle calculation unit 123, and a filter determination unit 124.

[0065] The filter storage unit 122 is a storage device for storing a plurality of stereophonic filters that are calculated and generated in advance for each sound arrival direction, as described above. The fluctuation angle calculation unit 123 is a processing unit that calculates the amount of fluctuation (angle amount) in a predetermined direction in a very short time based on sound information. For example, the fluctuation angle calculation unit 123 calculates the amount of fluctuation in a predetermined direction within a fixed period of time within a range of several milliseconds to several seconds from information on the predetermined direction. Here, the fluctuation angle calculation unit 123 calculates the angle difference when the angle difference in the predetermined direction becomes maximum within the above period as the above angle amount. The fluctuation angle calculation unit 123 compares the calculated angle amount with a threshold value. The comparison result, such as the calculated angle amount being smaller than the threshold value, is used by the filter determination unit 124 to determine the stereophonic filter to be selected.

[0066] The filter determination unit 124 is a processing unit that determines a stereophonic filter to be selected when the angle amount calculated by the above-mentioned fluctuation angle calculation unit 123 is smaller than a threshold value, so as to emphasize the predetermined sound and cause it to be perceived by the user 99. The stereophonic filter determined by the filter determination unit 124 is output by being read out from the filter storage unit 122, that is, is output as the stereophonic filter selected by the filter selection unit 121. Details of the determination of the stereophonic filter by the filter determination unit 124 (that is, the selection of the stereophonic filter by the filter selection unit 121) will be described later.

[0067] The output sound generation unit 131 is a processing unit that generates an output sound signal by using the stereophonic filter selected by the filter selection unit 121 and inputting information about a specific sound included in the sound information to the selected stereophonic filter.

[0068] Here, an example of the output sound generating unit 131 will be described with reference to FIG. 5. FIG. 5 is a block diagram showing a functional configuration of the output sound generating unit according to the embodiment. As shown in FIG. 5, the output sound generating unit 131 in the present embodiment includes, for example, a filter processing unit 132. The filter processing unit 132 sequentially reads in the filters continuously selected by the filter selection unit 121, and inputs information on the corresponding predetermined sound on the time axis, thereby continuously outputting a sound signal in which the arrival direction from which the predetermined sound arrives is controlled in the three-dimensional sound field. In this way, the sound information divided into processing unit times on the time axis is output as a continuous sound signal (output sound signal) on the time axis.

[0069] The signal output unit 141 is a functional unit that outputs the generated output sound signal to the driver 104. The signal output unit 141 generates a waveform signal by performing signal conversion from a digital signal to an analog signal based on the output sound signal, and generates sound waves in the driver 104 based on the waveform signal to present the sound to the user 99. The driver 104 has, for example, a diaphragm and a driving mechanism such as a magnet and a voice coil. The driver 104 operates the driving mechanism according to the waveform signal, and vibrates the diaphragm with the driving mechanism. In this way, the driver 104 generates sound waves by the vibration of the diaphragm according to the output sound signal, and the sound waves propagate through the air to the ears of the user 99, and the user 99 perceives the sound.

[0070] [Operation] Next, the operation of the above-described sound reproducing device 100 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the operation of the sound reproducing device according to the embodiment. First, when the operation of the sound reproducing device 100 is started, the acquisition unit 111 acquires sound information via the communication module 102. The sound information is decoded by the decoding processing unit 113 into information about a predetermined sound and information about a predetermined direction, and filter selection is started.

[0071] In the filter selection unit 121, a stereophonic filter that reproduces a predetermined sound so that the arrival direction is a direction preset in the content (a direction of arrival that matches the predetermined direction) is read from the filter storage unit 122 as an initial value. Meanwhile, the fluctuation angle calculation unit 123 calculates the amount of angle of fluctuation in the predetermined direction (S101). After that, the fluctuation angle calculation unit 123 determines whether the amount of angle of fluctuation is smaller than a threshold value (S102). If the amount of angle of fluctuation is equal to or larger than the threshold value (No in S102), the filter selection unit 121 ends the process and outputs to the output sound generation unit 131 a stereophonic filter whose arrival direction matches the predetermined direction.

[0072] On the other hand, if the amount of angle of the fluctuation is smaller than the threshold value (Yes in S102), the filter determination unit 124 determines a stereophonic filter (S103). The determination of a stereophonic filter can be interpreted as a selection for changing the stereophonic filter selected as the initial value. At this time, the arrival direction of the sound in the output sound signal is a direction different from the predetermined direction in the sound information.

[0073] Note that, without setting the initial value of the stereophonic filter as described above, the stereophonic filter determined by the filter determination unit 124 may be directly read from the filter storage unit 122. In other words, the change of the stereophonic filter is an expression used for convenience of explanation, and the present disclosure also includes directly selecting and outputting a stereophonic filter without using an initial value.

[0074] The determination of a stereophonic filter will be described below with reference to Figs. 7 to 9. Fig. 7 is a first diagram for explaining the arrival direction of a predetermined sound by a selected stereophonic filter according to an embodiment. Fig. 8 is a second diagram for explaining the arrival direction of a predetermined sound by a selected stereophonic filter according to an embodiment. Fig. 9 is a third diagram for explaining the arrival direction of a predetermined sound by a selected stereophonic filter according to an embodiment.

[0075] In Fig. 7, the direction of arrival of the predetermined sound when the stereophonic filter is not changed is shown on the left side of the white right arrow, the direction of arrival of the predetermined sound at the first time point is shown by a solid line, and the direction of arrival of the predetermined sound at the second time point following the first time point is shown by a dashed line. Also, in Fig. 7, the direction of arrival of the predetermined sound when the stereophonic filter is changed is shown on the right side of the white right arrow, the direction of arrival of the predetermined sound at the first time point is shown by a solid line, and the direction of arrival of the predetermined sound at the second time point following the first time point is shown by a dashed line. Also, in Fig. 7, a user 99 with a posture facing the top of the paper is shown as a circle with a "U" attached, and this user 99 is in an upright posture perpendicular to the paper.

[0076] Furthermore, in FIG. 7, the positions where the predetermined sounds are localized are indicated by black circles, and virtual speakers are also shown.

[0077] As shown in FIG. 7, the position where the first predetermined sound is localized at the first time point is the first position S1. If the stereophonic filter is not changed, the first predetermined sound moves to the second position S1a at the second time point. The predetermined direction rotates from a first direction connecting the first position S1 and the user 99 to a second direction connecting the second position S1a and the user 99. Note that the first predetermined sound moves linearly in both time and space between the first time point and the second time point. If the amount of rotation from the first direction to the second direction (the amount of change in the arrival direction of the predetermined sound) is smaller than a threshold value, it is difficult for the user 99 to recognize that the first predetermined sound has moved.

[0078] On the other hand, by changing the 3D sound filter, First predetermined sound has moved to a third position S1b at the second time point. The predetermined direction has rotated from a first direction connecting the first position S1 and the user 99 to a third direction connecting the third position S1b and the user 99. The angular difference between the second direction and the third direction (the angle expanded by the change) may be a fixed angle such as 5 degrees, 10 degrees, 15 degrees, or 20 degrees, or may be an angle at which the angular difference between the first direction and the third direction sufficiently exceeds the minimum discrimination angle of humans (approximately 10 degrees) based on the angular difference between the first direction and the second direction.

[0079] Also, the smaller the angle difference between the first direction and the second direction (i.e., the angle amount of the fluctuation in the predetermined direction on the original sound information) is, the larger the angle difference between the second direction and the third direction may be. Specifically, the filter determination unit 124 may determine the stereophonic filter such that the smaller the angle amount of the fluctuation in the predetermined direction on the original sound information is, the larger the angle amount of the fluctuation in the arrival direction of the output sound signal when the changed stereophonic filter is used. For example, as shown in FIG. 8, the third direction is determined by multiplying the expansion coefficient α (α>1), which is a coefficient that increases as the angle amount of the fluctuation in the predetermined direction on the sound information is smaller, by the angle difference between the first direction and the second direction, and the stereophonic filter is changed so that the predetermined sound at the second time point arrives from this third direction. Also, this expansion coefficient α may have a nonlinear relationship in order to expand the angle amount of the fluctuation due to the change as the angle amount of the fluctuation is smaller.

[0080] 7, the dashed line extending to the left and right of the user 99 indicates a virtual boundary surface dividing the user 99's head into the front and back. This boundary surface may be a surface along the ear canal of the user 99, a surface passing through the rearmost point of the user 99's auricle, or simply a surface passing through the center of gravity of the user 99's head. It is known that there is a difference in ease of hearing sounds before and after such a boundary surface, that is, in front and behind the user 99. Therefore, it is effective to make the characteristics of the stereophonic filter change different between the front side and the rear side of the boundary surface.

[0081] In FIG. 7, the position where the second predetermined sound is localized at the first time point is the fourth position S2. If there is no change in the stereophonic filter, this second predetermined sound moves to the fifth position S2a at the second time point. The predetermined direction rotates from the fourth direction connecting the fourth position S2 and the user 99 to the fifth direction connecting the fifth position S2a and the user 99. The first direction and the fourth direction are parallel, and the second direction and the fifth direction are parallel. Therefore, during the period from the first time point to the second time point, the angle amount of the fluctuation of the second predetermined sound is equal to the angle amount of the fluctuation of the first predetermined sound. However, since the second predetermined sound is on the rear side (behind the user 99) of the boundary surface, it can be said that the fluctuation is less likely to be recognized by the user 99 compared to the front side.

[0082] Therefore, the filter determination unit 124 determines the stereophonic filter so that the amount of variation of the arrival direction on the time axis when the stereophonic filter after the change is used when the predetermined direction is on the rear side of the boundary surface is larger than the amount of variation of the arrival direction on the time axis when the stereophonic filter after the change is used when the predetermined direction is on the front side of the boundary surface. For example, in FIG. 7, the localization position of the predetermined sound is changed from the fourth position S2 in the fourth direction to the sixth position S2b so that the variation angle is larger than the angle formed by the first direction and the third direction. The angle difference between the fifth direction and the sixth direction may be a fixed angle such as 10 degrees, 15 degrees, 20 degrees, or 25 degrees, or may be set to be an angle difference that is a coefficient such as 2 times, 3 times, 4 times, or 5 times the angle difference on the front side.

[0083] Another example of the determination of a stereophonic filter by the filter determination unit 124 is shown in Fig. 9. Fig. 9 shows a diagram of a configuration similar to that of Fig. 7, and the configuration after the stereophonic filter is changed (to the right of the white rightward arrow) is different. Note that Fig. 9 shows only the sound image on the front side of the boundary surface, and for the sake of readability, to the right of the white rightward arrow, the illustration of the first position S1 where the first predetermined sound at the first time point is localized is omitted.

[0084] As shown in FIG. 9, the first predetermined sound at the second time point may be localized at the seventh position S1c, and a stereophonic filter may be selected so that the first predetermined sound vibrates separately from the fluctuation of the predetermined direction in the sound information. Here, the first predetermined sound is shown vibrating within an angular region sandwiched between two dashed lines centered on the seventh position S1c. In this way, the first predetermined sound may be emphasized by a method that does not amplify the magnitude of the fluctuation of the arrival direction. In the example of FIG. 9, the first predetermined sound is made to fluctuate periodically and regularly, so that the user 99 can be made to pay attention to the first predetermined sound, and even if the change is somewhat small, the user 99 can easily recognize it by paying attention to it.

[0085] Such periodic and regular fluctuations can be generated by multiplying or adding an oscillatory function whose value oscillates on the time axis, such as a sine function or a cosine function, to the angular amount of fluctuation in the arrival direction of the predetermined sound. For example, the arrival direction (corresponding to the changed angular amount) at the Nth (N is an integer of 2 or more) time point on the time axis of the output sound signal when the changed stereophonic filter is used may be calculated by multiplying the difference value (original angular amount) between the predetermined direction on the sound information corresponding to the (N-1)th time point on the time axis of the output sound signal and the predetermined direction on the sound information corresponding to the Nth time point by the numerical value of the corresponding time point in the oscillatory function, and adding the difference value after multiplication to the predetermined direction on the sound information corresponding to the (N-1)th time point.

[0086] In addition, in order to emphasize the direction from which the predetermined sound comes at the second time point, the stereophonic filter may be changed so that the amount of change in the sound pressure of the predetermined sound on the time axis perceived by the output sound signal when using the stereophonic filter after the change is greater than when using the stereophonic filter before the change. Also, these examples of changing the stereophonic filter are not mutually exclusive and may be used in any combination.

[0087] In this manner, in this embodiment, when the variation in the arrival direction of a predetermined sound is smaller than a threshold, the phenomenon that the variation is difficult for the user 99 to recognize can be suppressed by changing the stereophonic filter to generate an output sound signal so as to emphasize the variation. Therefore, small variations in the arrival direction of a predetermined sound that are difficult for the user 99 to recognize become clearer, so that the user 99 can more appropriately perceive a stereophonic sound.

[0088] (Other embodiments) Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments.

[0089] For example, in the above embodiment, an example was described in which sound does not follow the movement of the user's head, but the contents of the present disclosure are also effective in cases in which sound follows the movement of the user's head. In other words, in an operation in which a user perceives a predetermined sound as a sound arriving from a first position that moves relatively with the movement of the user's head, if the amount of variation in the arrival direction of the predetermined sound is smaller than a threshold, a stereophonic filter may be selected to emphasize the variation.

[0090] Also, for example, the sound reproducing device described in the above embodiment may be realized as a single device including all the components, or may be realized by allocating each function to a plurality of devices and coordinating the functions of the plurality of devices. In the latter case, an information processing device such as a smartphone, a tablet terminal, or a PC may be used as the device corresponding to the processing module.

[0091] As a configuration different from the above embodiment, for example, the decoding processing unit can correct the original sound information to select a modified stereophonic filter. Specifically, the decoding processing unit in this example is a processing unit that generates information about a specific direction included in the sound information and corrects the original sound information. The decoding processing unit calculates the angle amount of the fluctuation in the specific direction on the time axis, and when the calculated angle amount of the fluctuation in the specific direction is smaller than a threshold value, corrects the information about the specific direction so that the specific sound is more emphasized and perceived by the user than when the angle amount of the fluctuation in the specific direction is equal to or greater than the threshold value. As a result, the modified stereophonic filter in the above embodiment is applied simply by selecting a stereophonic filter that specifies the direction from which the specific sound arrives based on the corrected information about the specific direction output from the decoding processing unit.

[0092] In this way, the information processing method and the like disclosed in the present application may be realized by correcting information about a specific direction in the original sound information. For example, by simply inserting the above-mentioned decoding processing unit in place of a processing unit that performs decoding processing in a conventional stereophonic sound reproducing device, it is possible to realize a sound reproducing device that can achieve the same effect as that disclosed in the present application.

[0093] The sound reproducing device of the present disclosure can also be realized as a sound processing device that is connected to a reproducing device having only a driver and outputs an output sound signal to the reproducing device using a stereophonic filter selected based on the acquired sound information. In this case, the sound processing device may be realized as hardware having a dedicated circuit, or as software for causing a general-purpose processor to execute a specific process.

[0094] In the above embodiment, the processes executed by a specific processing unit may be executed by another processing unit. The order of multiple processes may be changed, or multiple processes may be executed in parallel.

[0095] In the above-described embodiment, each component may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

[0096] Furthermore, each component may be realized by hardware. For example, each component may be a circuit (or an integrated circuit). These circuits may form a single circuit as a whole, or each may be a separate circuit. Furthermore, each of these circuits may be a general-purpose circuit, or a dedicated circuit.

[0097] In addition, the general or specific aspects of the present disclosure may be realized in an apparatus, a device, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM. In addition, the general or specific aspects of the present disclosure may be realized in any combination of an apparatus, a device, a method, an integrated circuit, a computer program, and a recording medium.

[0098] For example, the present disclosure may be realized as an audio signal reproducing method executed by a computer, or as a program for causing a computer to execute the audio signal reproducing method. The present disclosure may be realized as a computer-readable non-transitory recording medium having such a program recorded thereon.

[0099] In addition, the present disclosure also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art may conceive, or forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the spirit of the present disclosure. [Industrial Applicability]

[0100] The present disclosure is useful in reproducing sound, for example, by allowing a user to perceive stereoscopic sound. [Explanation of symbols]

[0101] 99 users 100 Sound reproduction device 101 Processing Module 102 Communication module 103 Detector 104 Driver 111 Acquisition Department 112 Encoded audio information input section 113 Decoding processing unit 114 Sensing information input section 121 Filter selection section 122 Filter memory section 123 Fluctuation angle calculation unit 124 Filter Determination Unit 131 Output sound generation unit 132 Filter processing section 141 Signal output section 200 3D image playback device S1 1st position S1a 2nd position S1b 3rd position S1c 7th position S2 4th position S2a 5th position S2b 6th position

Claims

1. An information processing method for generating an output sound signal for allowing a user to perceive a predetermined sound along a time series as a sound arriving from an arrival direction in a three-dimensional sound field corresponding to the predetermined direction from sound information including information about the predetermined sound and information about a predetermined direction at each point on a time axis, the method comprising: Calculating an angular amount of the fluctuation in the predetermined direction on a time axis; Selecting a stereophonic filter that causes the input sound to be perceived as a sound from the direction of arrival based on the information about the predetermined direction from among a plurality of candidate stereophonic filters prepared for each direction of arrival; inputting information about the predetermined sound into the selected stereophonic filter to generate the output sound signal; In the selection of the stereophonic filter, when the calculated angular amount of the variation in the predetermined direction is smaller than a threshold value, the stereophonic filter is selected so that the predetermined sound is more emphasized and perceived by the user than when the angular amount of the variation in the predetermined direction is equal to or larger than the threshold value. Information processing methods.

2. In the selection of the stereophonic filter, when the calculated angular amount of the variation in the predetermined direction is smaller than a threshold value, the stereophonic filter is selected so that the angular amount of the variation in the arrival direction perceived by the output sound signal when the selected stereophonic filter is used is larger than the angular amount of the variation in the arrival direction perceived by the output sound signal when the stereophonic filter selected when the calculated angular amount of the variation in the predetermined direction is equal to or larger than a threshold value. The information processing method according to claim 1 .

3. In the selection of the stereophonic filter, the stereophonic filter is selected such that the smaller the calculated angular amount of the fluctuation in the predetermined direction, the larger the angular amount of the fluctuation in the arrival direction perceived by the output sound signal when the selected stereophonic filter is used. The information processing method according to claim 2 .

4. When the calculated angle amount of the fluctuation in the predetermined direction is smaller than a threshold value, when the selected stereophonic filter is used, the smaller the angle amount of the fluctuation in the predetermined direction on the sound information, the larger the expansion coefficient α (α>1) is multiplied, thereby expanding the angle amount of the fluctuation in the arrival direction on the time axis of the output sound signal, The relationship between the angular amount of the fluctuation in the predetermined direction and the expansion coefficient α is nonlinear. The information processing method according to claim 3.

5. In the selection of the stereophonic filter, when the predetermined direction is on the front side of a virtual boundary plane dividing the user's head into front and rear, and the calculated angular amount of the fluctuation in the predetermined direction is smaller than a threshold value, the stereophonic filter is selected so that the angular amount of the fluctuation in the arrival direction on the time axis when the selected stereophonic filter is used is larger than the angular amount of the fluctuation in the arrival direction on the time axis when the selected stereophonic filter is used, when the predetermined direction is on the rear side of the boundary plane and the calculated angular amount of the fluctuation in the predetermined direction is smaller than a threshold value. The information processing method according to any one of claims 2 to 4.

6. In the selection of the stereophonic filter, the stereophonic filter is selected so that the arrival direction perceived by the output sound signal when the selected stereophonic filter is used vibrates on the time axis compared to the predetermined direction in the sound information. The information processing method according to any one of claims 1 to 5.

7. When the selected stereophonic filter is used, the arrival direction at the Nth (N is an integer equal to or greater than 2) time point on the time axis of the output sound signal is expressed as follows: multiplying a difference value between the predetermined direction on the sound information corresponding to the (N-1)th time point on the time axis of the output sound signal and the predetermined direction on the sound information corresponding to the Nth time point by a numerical value at a corresponding time point in an oscillation function whose numerical value oscillates on the time axis; The difference value after multiplication is added in the predetermined direction on the sound information corresponding to the (N-1)th time point. The information processing method according to claim 6.

8. In the selection of the stereophonic filter, when the calculated angular amount of the fluctuation in the predetermined direction is smaller than a threshold value, the stereophonic filter is selected so that the amount of change in the sound pressure of the predetermined sound on the time axis perceived by the output sound signal when the selected stereophonic filter is used is greater than the amount of change in the sound pressure of the predetermined sound perceived by the output sound signal when the stereophonic filter selected when the calculated angular amount of the fluctuation in the predetermined direction is equal to or greater than a threshold value is used. The information processing method according to claim 1 .

9. An information processing method for generating an output sound signal for allowing a user to perceive a predetermined sound along a time series as a sound arriving from an arrival direction in a three-dimensional sound field corresponding to the predetermined direction from sound information including information about the predetermined sound and information about a predetermined direction at each point on a time axis, the method comprising: Calculating an angular amount of the fluctuation in the predetermined direction on a time axis; correcting information about the predetermined direction such that, when the calculated angle amount of the change in the predetermined direction is smaller than a threshold value, the predetermined sound is perceived by the user with greater emphasis than when the calculated angle amount of the change in the predetermined direction is equal to or greater than the threshold value; The information about the predetermined sound is input to a plurality of candidate stereophonic filters, which are prepared for each arrival direction, and a stereophonic filter selected based on the information about the predetermined direction after correction is input to generate the output sound signal. Information processing methods.

10. A method for causing a computer to execute the information processing method according to any one of claims 1 to 9. program.

11. 1. A sound reproducing device that generates and reproduces an output sound signal from sound information including information about a predetermined sound and information about a predetermined direction at each point on a time axis, for allowing a user to perceive the predetermined sound as a sound coming from an arrival direction in a three-dimensional sound field corresponding to the predetermined direction, An acquisition unit that acquires the sound information; a filter selection unit that calculates an angle amount of the fluctuation in the predetermined direction on a time axis and selects a stereophonic filter that causes an input sound to be perceived as a sound from the arrival direction based on information about the predetermined direction, from among a plurality of candidate stereophonic filters prepared for each arrival direction; an output sound generating unit that inputs information about the predetermined sound as the input sound to the selected stereophonic filter to generate the output sound signal; an output unit that outputs a sound based on the generated output sound signal, The filter selection unit selects the stereophonic filter when the calculated angular amount of the variation in the predetermined direction is smaller than a threshold value so that the predetermined sound is more emphasized and perceived by the user than when the angular amount of the variation in the predetermined direction is equal to or larger than the threshold value. Sound reproduction device.

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