Processing apparatus, system, processing method, and program

Abstract

A signal processing device according to an embodiment of the present disclosure has: a reception means for receiving an input acoustic signal; a generation means for performing a modulation process including amplitude modulation on the input acoustic signal received by the reception means, and thereby generating a modulated acoustic signal having a change in amplitude corresponding to the frequency of gamma waves; and an output means for outputting content that includes the modulated acoustic signal generated by the generation means, and modulation information relating to the modulation process performed in order to generate the modulated acoustic signal, in association with each other.

Description

Signal processing device, cognitive function improvement system, signal processing method, and program

[0001] The present disclosure relates to a signal processing device, a cognitive function improvement system, a signal processing method, and a program.

[0002] There is a research report that suggests that inducing gamma waves in the brain of an organism by subjecting it to pulsed sound stimuli at a frequency of about 40 times per second is effective in improving the organism's cognitive function (see Non-Patent Document 1). Gamma waves refer to neural oscillations that capture periodic neural activity in the brain's cortex using electrophysiological techniques such as electroencephalography and magnetoencephalography, and that have frequencies in the gamma band (25-140 Hz).

[0003] Patent document 1 discloses adjusting the volume by increasing or decreasing the amplitude of a sound wave or sound track to create a rhythmic stimulus corresponding to a stimulus frequency that induces brain wave entrainment.

[0004] Special Publication No. 2020-501853

[0005] Multi-sensory Gamma Stimulation Ameliorates Alzheimer's-Associated Pathology and Improves Cognition Cell 2019 Apr 4;177(2):256-271.e22. doi: 10.1016 / j.cell.2019.02.014.

[0006] When playing content including an audio signal, if it is unclear whether the content includes an amplitude-modulated audio signal, and if so, what type of amplitude modulation is used, it may cause inconvenience to the user. For example, a user hoping to improve cognitive function may not be able to easily determine which content to listen to or watch and for how long.

[0007] An object of the present disclosure is to provide a technology that improves user convenience in determining content to be played back or determining how to listen to or watch that content.

[0008] A signal processing device according to one aspect of the present disclosure includes a receiving means for receiving an input acoustic signal, a generating means for performing a modulation process including amplitude modulation on the input acoustic signal received by the receiving means to generate a modulated acoustic signal having an amplitude change corresponding to the frequency of gamma waves, and an output means for outputting content including the modulated acoustic signal generated by the generating means in association with modulation information regarding the modulation process performed to generate the modulated acoustic signal.

[0009] 1 is a block diagram showing the configuration of a cognitive function improvement system of the present embodiment. FIG. 2 is a block diagram showing the configuration of a content playback device of the present embodiment. FIG. 3 is a block diagram showing the configuration of a content distribution device of the present embodiment. FIG. 4 is an explanatory diagram of one aspect of the present embodiment. FIG. 5 is a flowchart of content distribution processing of the present embodiment. FIG. 6 is a diagram showing an example of a score function used in the content distribution processing of the present embodiment. FIG. 7 is a flowchart of content playback processing of the present embodiment. FIG. 8 is a diagram showing an example of a screen displayed in the content playback processing of the present embodiment. FIG. 9 is a flowchart of content distribution processing of modified example 1. FIG. 10 is a flowchart of content playback processing of modified example 1. FIG. 11 is a flowchart of content playback processing of modified example 2.

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated description thereof will be omitted.

[0011] (1) Configuration of the cognitive function improvement system The configuration of the cognitive function improvement system will be described below. Fig. 1 is a block diagram showing the configuration of the cognitive function improvement system of this embodiment.

[0012] As shown in FIG. 1 , the cognitive function improvement system 1 includes a content playback device 10 and a content distribution device 30 .

[0013] A transmission path for distributing content is provided between the content playback device 10 and the content distribution device 30. The content may be broadcast content or on-demand distribution content. In this embodiment, the distributed content includes audio content. Note that the content distribution device 30 may distribute content including audio content and video content (e.g., TV programs or uploaded MP4 files). The transmission path may be a transmission path for information communication or a transmission path for broadcasting. The transmission path for information communication may include a network (e.g., the Internet or an intranet) or a predetermined interface (e.g., a wireless interface using Bluetooth or the like). The transmission path for broadcasting may include, for example, a broadcast network for TV broadcasting.

[0014] The content playback device 10 acquires content distributed from the content distribution device 30 and plays back the content. The content playback device 10 is an example of a signal processing device. The content playback device 10 is, for example, a TV, a set-top box, a radio, a music player, a smartphone, a PC, an electronic musical instrument, a telephone, a game console, or an amusement machine.

[0015] The content distribution device 30 distributes content to the content reproduction device 10. The content distribution device 30 is an example of a signal processing device.

[0016] (1-1) Configuration of the Content Reproducing Apparatus The configuration of the content reproducing apparatus will be described below. Fig. 2 is a block diagram showing the configuration of the content reproducing apparatus of this embodiment.

[0017] 2, the content reproduction device 10 includes a storage device 11, a processor 12, an input / output interface 13, and a communication interface 14. The content reproduction device 10 is connected to a display 21 and an audio output device 22.

[0018] The storage device 11 is configured to store programs and data. The storage device 11 is, for example, a combination of a read-only memory (ROM), a random access memory (RAM), and storage (for example, a flash memory or a hard disk). The programs and data may be provided via a network, or may be provided by being recorded on a computer-readable recording medium.

[0019] The programs include, for example, the following: OS (Operating System) programs; and application programs that execute information processing.

[0020] The data includes, for example, the following data: Databases referenced in information processing Data obtained by executing information processing (i.e., execution results of information processing)

[0021] The processor 12 is a computer that implements the functions of the content playback device 10 by reading and executing programs stored in the storage device 11. Note that at least some of the functions of the content playback device 10 may be implemented by one or more dedicated circuits. The processor 12 is, for example, at least one of the following: CPU (Central Processing Unit) GPU (Graphic Processing Unit) ASIC (Application Specific Integrated Circuit) FPGA (Field Programmable Array) DSP (Digital Signal Processor)

[0022] The input / output interface 13 is configured to acquire information (e.g., user instructions) from an input device connected to the content playback device 10, and to output information (e.g., image signals, audio signals, or control signals) to an output device connected to the content playback device 10. The input device is, for example, a physical button, a keyboard, a pointing device, a touch panel, or a combination thereof. The output device is, for example, a display 21, an audio output device 22, or a combination thereof.

[0023] Furthermore, the input / output interface 13 may include signal processing hardware such as an A / D converter, a D / A converter, an amplifier, a mixer, a filter, and the like.

[0024] The communication interface 14 is configured to control communication between the content reproduction device 10 and an external device (for example, the content distribution device 30).

[0025] The display 21 is configured to display an image (still image or moving image) and is, for example, a liquid crystal display or an organic EL display.

[0026] The audio output device 22 generates sound in response to the output audio signal. The audio output device 22 is, for example, a loudspeaker (which may include a speaker with a built-in amplifier (a powered speaker)), headphones, earphones, or a smart speaker.

[0027] The audio output device 22 is connected to the processor 12 via a predetermined interface capable of transmitting audio signals, and acquires output audio signals from the processor 12. The interface is, for example, a Sony Philips Digital Interface (SPDIF), a High-Definition Multimedia Interface (HDMI (registered trademark)), a pin connector (RCA pin), or an audio interface for headphones. The interface may also be a wireless interface using Bluetooth (registered trademark) or the like. The audio signal in this embodiment includes either or both of an analog signal and a digital signal.

[0028] (1-2) Configuration of the Content Distribution Device The configuration of the content distribution device will be described below. Fig. 3 is a block diagram showing the configuration of the content distribution device of this embodiment.

[0029] 3, the content distribution device 30 includes a storage device 31, a processor 32, an input / output interface 33, and a communication interface 34. The content distribution device 30 is connected to a sound source device 41.

[0030] The storage device 31 is configured to store programs and data. The storage device 31 is, for example, a combination of ROM, RAM, and storage (for example, flash memory or a hard disk). The programs and data may be provided via a network, or may be provided by being recorded on a computer-readable recording medium.

[0031] The programs include, for example, the following programs: OS programs; application programs for executing information processing.

[0032] The data includes, for example, the following data: Databases referenced in information processing Execution results of information processing

[0033] The processor 32 is a computer that realizes the functions of the content distribution device 30 by reading and executing programs stored in the storage device 31. Note that at least some of the functions of the content distribution device 30 may be realized by one or more dedicated circuits. The processor 32 is, for example, at least one of the following: CPU GPU ASIC FPGA DSP

[0034] The input / output interface 33 is configured to acquire information (e.g., user instructions or audio signals) from an input device connected to the content distribution apparatus 30, and to output information (e.g., image signals) to an output device connected to the content distribution apparatus 30. The input device is, for example, a sound source apparatus 41, a physical button, a keyboard, a pointing device, a touch panel, or a combination thereof. The output device is, for example, a display, a speaker, or a combination thereof.

[0035] The communication interface 34 is configured to control communication between the content distribution device 30 and an external device (for example, the content reproduction device 10).

[0036] The sound source device 41 is configured to generate and transmit an input sound signal.

[0037] (2) One aspect of the embodiment One aspect of the present embodiment will be described below. Fig. 4 is an explanatory diagram of one aspect of the present embodiment.

[0038] As shown in Fig. 4, the content distribution device 30 performs amplitude modulation processing on the acoustic signal. The content distribution device 30 also generates meta information related to the content for improving cognitive function. The meta information may include, for example, information related to the amplitude modulation performed on the acoustic signal (hereinafter referred to as "modulation information"). The content distribution device 30 distributes the content including the acoustic signal (output acoustic signal) generated by the amplitude modulation processing and the meta information to the content playback device 10.

[0039] The content playback device 10 plays content acquired from the content distribution device 30. The content playback device 10 outputs an audio signal (output audio signal) included in the content to the audio output device 22. Because the output audio signal has amplitude variations corresponding to the frequency of gamma waves, when the user US 10 listens to the sound generated by the output audio signal, gamma waves are induced in the brain of the user US 10 (brain waves are synchronized to the gamma frequency). This can be expected to improve cognitive function (e.g., treat or prevent dementia). Here, the content playback device 10 controls content playback based on meta information acquired from the content distribution device 30. As an example, the content playback device 10 displays information based on the meta information (e.g., information regarding the degree of cognitive function improvement expected from viewing the content) on the display 21. Note that in the following description, the term "viewing" is used in a sense that includes "listening." By checking such information, the user US10 can easily determine whether to continue viewing the content currently being played or switch to other content, or for how long to continue viewing the content currently being played.

[0040] (3) Information Processing Information processing in this embodiment will be described.

[0041] (3-1) Content Distribution Processing The content distribution processing of this embodiment will be described. Fig. 5 is a flowchart of the content distribution processing of this embodiment. Fig. 6 is a diagram showing an example of a score function used in the content distribution processing of this embodiment.

[0042] The content distribution process of FIG. 5 is realized by the processor 32 of the content distribution device 30 reading and executing a program stored in the storage device 31.

[0043] The content distribution process in Fig. 5 starts when any of the following start conditions is met: The content distribution process in Fig. 5 is called by another process or an external instruction. The user of the content playback device 10 performs an operation to call the content distribution process in Fig. 5. The content distribution device 30 enters a predetermined state (e.g., power is turned on). A predetermined date and time arrives. A predetermined time has passed since a predetermined event (e.g., startup of the content distribution device 30 or the previous execution of the content distribution process in Fig. 5).

[0044] 5, the content distribution device 30 acquires an input acoustic signal (S130). Specifically, the content distribution device 30 receives an input acoustic signal transmitted from the sound source device 41. Alternatively, the processor 32 may read content including the input acoustic signal from the storage device 31 and extract the input acoustic signal (which may include demultiplexing and decoding). In step S130, the content distribution device 30 may further perform A / D conversion of the input acoustic signal.

[0045] The input audio signal corresponds to, for example, at least one of the following: Musical content (e.g., singing, playing, or a combination thereof (i.e., a song); may include musical content accompanying video content) Audio content (e.g., reading, narration, announcement, broadcast drama, solo performance, conversation, monologue, or a combination thereof; may include audio content accompanying video content) Other audio content (e.g., electronic sounds, environmental sounds, or mechanical sounds) However, singing or audio content is not limited to sounds produced by human vocal organs, and may include sounds generated by voice synthesis technology.

[0046] After step S130, the content distribution device 30 performs modulation of the acoustic signal (S131). Specifically, the content distribution device 30 generates an output acoustic signal by at least partially amplitude modulating the input acoustic signal acquired in step S130.

[0047] As a first example of modulating an audio signal (S131), the content distribution device 30 generates an intermediate audio signal including a plurality of audio signals having different characteristics based on an input audio signal. Here, the characteristics may be determined based on an input operation by a creator or provider of the content corresponding to the input audio signal, an external instruction, or an algorithm. For example, the content distribution device 30 may determine the characteristics for generating the intermediate audio signal based on the results of analyzing the input audio signal.

[0048] The features may be, for example, at least one of the following: sound features (particularly qualitative features); frequency features; time features; amplitude features; power features.

[0049] The content distribution device 30 selects one or more audio signals (hereinafter referred to as "target signals") to which amplitude modulation is to be applied from the multiple audio signals included in the intermediate audio signal. The audio signals to be selected as target signals may be determined based on an input operation by the creator or provider of the content corresponding to the input audio signal, an external instruction, or an algorithm. For example, the content distribution device 30 may determine the target signal based on characteristics of the audio signal (balance between speech and music, volume change, type of music, timbre, or other characteristics). This allows the content distribution device 30 to select a target signal that maximizes the cognitive function improvement effect of modulation or minimizes discomfort experienced by viewers of the content (i.e., users of the content playback device 10). However, the content distribution device 30 may treat all of the multiple audio signals included in the intermediate audio signal as target signals.

[0050] The content distribution device 30 performs amplitude modulation on the selected target signal. As an example, the content distribution device 30 performs amplitude modulation on the target signal using a modulation function having a frequency corresponding to gamma waves (e.g., a frequency of 35 Hz to 45 Hz). Specifically, if A(t) is a modulation function having a periodicity of 35 Hz to 45 Hz, X(t) is a function representing the waveform of the audio signal before modulation, and Y(t) is a function representing the waveform of the modulated audio signal, then Y(t) = A(t) · X(t). As a result, an amplitude change corresponding to the above frequency is added to the target signal. Here, the content distribution device 30 may determine a modulation function to be used for amplitude modulation of the target signal or a modulation depth for the amplitude modulation. The modulation function or modulation depth may be determined based on an input operation by the creator or provider of the content corresponding to the input audio signal, an external instruction, or an algorithm. Furthermore, the content distribution device 30 may determine a common modulation function or modulation depth for multiple target signals, or may determine a modulation function or modulation depth individually for multiple target signals.

[0051] The content distribution device 30 generates an output audio signal based on audio signals not selected as target signals (hereinafter referred to as "non-target signals") among the multiple audio signals included in the intermediate audio signal and the modulated target signal. That is, the content distribution device 30 converts the non-target signals and the modulated target signals into an output audio signal. Specifically, the content distribution device 30 combines two or more audio signals from the non-target signals and the modulated target signals, or extracts or separates an audio signal from at least one of the non-target signals and the modulated target signals. The audio signal combining method is not limited, and may include, for example, signal summation, HRTF (Head Related Transfer Function) convolution, convolution with a transfer function that provides sound source position information, or summation after these convolution processes. The content distribution device 30 may also perform at least one of amplification, volume adjustment, and D / A conversion of the output audio signal. On the other hand, if the asymmetric signal and the modulated target signal match the format of a distributable audio signal or the output format of the content reproduction device 10 (for example, if the asymmetric signal and the modulated target signal correspond to multi-channel audio signals associated with the respective speakers that make up a surround system as the content reproduction device 10), such conversion is not necessary. In this case, the asymmetric signal and the modulated target signal are treated as output audio signals.

[0052] In a second example of the modulation of an acoustic signal (S131), the input acoustic signal includes a plurality of acoustic signals having different characteristics. The content distribution device 30 selects one or more acoustic signals to which amplitude modulation is to be applied from the plurality of acoustic signals included in the input acoustic signal. The second example of the modulation of an acoustic signal (S131) ​​can be understood by appropriately replacing the "intermediate acoustic signal" with the "input acoustic signal" in the description of the first example above.

[0053] In a third example of modulation of an audio signal (S131), the content distribution device 30 performs amplitude modulation on the input audio signal. The amplitude modulation of the input audio signal is similar to the amplitude modulation of the target signal described in the first example of modulation of an audio signal (S131). As a result, an amplitude change corresponding to the frequency of gamma waves is added to the input audio signal. Here, the content distribution device 30 may determine a modulation function to be used for amplitude modulation of the input audio signal or a modulation depth of the amplitude modulation. The modulation function or modulation depth may be determined based on an input operation by the creator or provider of the content corresponding to the input audio signal, an external instruction, or an algorithm.

[0054] The content distribution device 30 generates an output audio signal based on the modulated input audio signal. That is, the content distribution device 30 converts the modulated input audio signal into an output audio signal. Specifically, when the modulated input audio signal consists of multiple audio signals, the content distribution device 30 combines two or more of the multiple audio signals, or extracts or separates an audio signal from the modulated input audio signal. Details of the audio signal combination method are as described in the first example of audio signal modulation (S131). On the other hand, if the modulated input audio signal matches the format of an audio signal that can be distributed or the output format of the content playback device 10 (for example, if the modulated input audio signal corresponds to a multi-channel audio signal associated with each speaker that constitutes a surround system as the content playback device 10), such conversion is not necessary. In this case, the modulated input audio signal is treated as the output audio signal.

[0055] After step S131, the content distribution device 30 generates meta information (S132). Specifically, the content distribution device 30 generates meta information according to the processing performed in modulating the acoustic signal (S131). The meta information may include, for example, at least one of the following information: - Information (e.g., a flag) indicating that it is possible to select the playback of sound based on the output acoustic signal (i.e., the acoustic signal to which amplitude modulation has been applied) - Modulation information - Feature information - Ideal viewing conditions for the content (e.g., playback volume) - Content type - Score

[0056] Modulation information is information about the processing performed to generate an output audio signal included in content. For example, the modulation information may include information about at least one of the following: modulation function used for amplitude modulation modulation depth audio signal to which amplitude modulation has been applied audio signal to which amplitude modulation has not been applied. Here, when an intermediate audio signal including multiple audio signals is generated based on an input audio signal and whether or not amplitude modulation is applied to each of the multiple audio signals is determined individually, each of the multiple audio signals corresponds to either an "audio signal to which amplitude modulation has been applied" or an "audio signal to which amplitude modulation has not been applied." Similarly, when an input audio signal is made up of multiple audio signals and whether or not amplitude modulation is applied to each of the multiple audio signals is determined individually, each of the multiple audio signals corresponds to either an "audio signal to which amplitude modulation has been applied" or an "audio signal to which amplitude modulation has not been applied." In these cases, since the function used for amplitude modulation or the modulation depth may differ for each of the audio signals to which amplitude modulation has been applied, the modulation information may include information about the "function used for amplitude modulation" or "modulation depth" of each audio signal.

[0057] The feature information is information about the feature of an audio signal to which amplitude modulation has been applied in order to generate an output audio signal included in content. For example, the feature information may include information about at least one of the following: - Distribution of amplitude, energy, or effective value in the frequency domain (e.g., the result of a fast Fourier transform (FFT)) - Distribution of amplitude, energy, or effective value in the time domain - Sound source type (e.g., vocals, musical instruments, objects, music, conversational voices, natural sounds, electronic sounds, etc.) - Sound source type for each playback section - Content attributes (e.g., program information for a TV program in which the audio signal is included)

[0058] The score is information regarding the magnitude of the expected effect of improving cognitive function when a user listens to sounds included in the reproduced content in an ideal listening environment. Regarding the calculation of the score, for example, the content distribution device 30 can refer to a score function for deriving a score corresponding to some or all of the following factors: - Length of time for which the content (output acoustic signal) continues to be reproduced (i.e., listening period) - Reproduction volume of the content in an ideal listening environment - Modulation method for amplitude modulation applied to the acoustic signal - Feature quantity of the acoustic signal to which amplitude modulation has been applied The score function may be stored in the storage device 31 or may be stored in a storage device included in an external device (e.g., a server) accessible by the content distribution device 30.

[0059] Here, the score represents the degree of improvement in cognitive function and is defined to correlate with the estimated results of the amount of EEG induction caused by sound stimulation (i.e., the degree to which gamma waves are induced), an index calculated from the degree of EEG synchronization at each time (i.e., the duration for which gamma wave synchronization was achieved), or an index calculated from the EEG induction ratio at each time (i.e., the history of the degree to which gamma waves are induced compared to other EEG bands). As one example, the score is determined to increase (e.g., linearly increase) with an increase in the amount of EEG induction. As another example, the score is determined to increase little when the amount of EEG induction is below a first threshold, and to increase with an increase in the amount of EEG induction after the amount of EEG induction exceeds the first threshold. As yet another example, the score is determined to increase with an increase in the amount of EEG induction when the amount of EEG induction is below a second threshold, and to increase little (i.e., saturate) after the amount of EEG induction exceeds the second threshold. By measuring the brain wave elicitation level of a subject when the subject listens to various acoustic signals under various conditions using an electroencephalograph, it is possible to describe the relationship between the elements included in the meta information and the brain wave elicitation level.Based on the relationship between the elements included in the meta information and the brain wave elicitation level and the relationship between the score and the brain wave elicitation level, a score function can be created to derive a score corresponding to the element included in the meta information.The score function may be defined as a mathematical formula using the above-mentioned elements as arguments, or may be defined as a look-up table.

[0060] As an example, the content distribution device 30 calculates the score using the score function shown in Fig. 6. In the score function of Fig. 6, the score is defined so that it increases or remains the same (in other words, it does not decrease) as the listening period increases. Also, in the score function of Fig. 6, the score is defined so that the score for a playback volume C1 is higher than the score for a playback volume C2 (lower than C1).

[0061] The content distribution device 30 may determine details of the modulation process to be performed in step S131 so that the score or the score increment is equal to or greater than a reference value. For example, if the score calculated in step S132 is below the reference value or if the cumulative score value estimated from the current score increment is below the reference value, the content distribution device 30 may change the modulation settings and re-execute step S131. The content distribution device 30 may generate meta information (S132) and then modulate the acoustic signal (S131). In this case, for example, the content distribution device 30 may generate meta information indicating a predetermined score, and then determine details of the modulation process so that the score of the modulated content is equal to or greater than the predetermined score, and then perform the modulation process on the content.

[0062] After step S132, the content distribution device 30 executes content distribution (S133). Specifically, the content distribution device 30 distributes content including the output acoustic signal generated in step S131 to the content reproduction device 10 together with the meta information generated in step S132. As an example, the content distribution device 30 may generate a content file in a predetermined format by multiplexing the output acoustic signal and the meta information. Alternatively, the content distribution device 30 may distribute the content file and the meta information via separate transmission paths. For example, the content distribution device 30 may distribute the content file via normal broadcasting and the meta information via data broadcasting or the Internet.

[0063] The content distribution device 30 may also include an unprocessed audio signal in the content file. The unprocessed audio signal may be identical to the output audio signal except for the presence or absence of amplitude modulation. A content viewer can select whether to listen to sound based on the unprocessed audio signal or sound based on the output audio signal. For example, the content distribution device 30 may distribute an unprocessed audio signal as audio data for the main audio of a TV program and an output audio signal as audio data for the secondary audio. For example, the content distribution device 30 may distribute an unprocessed audio signal as audio data for a first subchannel of a multi-channel TV program and an output audio signal as audio data for a second subchannel. In this case, a TV viewer can easily select whether to play the unprocessed audio signal or the output audio signal by switching between the main audio and secondary audio or by switching the viewing channel. The content distribution device 30 may also include an image signal (a moving image signal or a still image signal) in the content file. The content distribution device 30 may also distribute multiple contents that include the same image signal but different audio signals (e.g., an output audio signal and an unprocessed audio signal). Furthermore, the content distribution device 30 may perform encoding (compression) processing before multiplexing various types of information.

[0064] The content distribution device 30 ends the content distribution process of FIG. 5 at step S133. The content distribution device 30 may perform the content distribution process of FIG. 5 all at once for an input audio signal having a fixed playback period (e.g., one piece of music content), or may repeatedly perform the content distribution process of FIG. 5 for each predetermined playback section of the input audio signal (e.g., every 100 ms). Alternatively, the content distribution device 30 may continuously perform modulation processing on the input audio signal, such as modulation using analog signal processing, and output the modulated audio signal. The content distribution process of FIG. 5 may end in response to a specific end condition (e.g., the passage of a certain amount of time, an operation by the creator or provider of the content or the user of the content playback device 10, or the output history of the modulated sound reaching a predetermined state).

[0065] (3-2) Content Playback Processing The content playback processing of this embodiment will now be described. Fig. 7 is a flowchart of the content playback processing of this embodiment. Fig. 8 is a diagram showing an example of a screen displayed in the content playback processing of this embodiment. Fig. 9 is a diagram showing an example of a screen displayed in the content playback processing of this embodiment.

[0066] The content playback process in Fig. 7 starts when any of the following start conditions is met: The content playback process in Fig. 7 is called by another process or an external instruction. The user performs an operation to call the content playback process in Fig. 7. The content playback device 10 enters a predetermined state (e.g., power is turned on). A predetermined date and time arrives. A predetermined time has passed since a predetermined event (e.g., startup of the content playback device 10 or the previous execution of the content playback process in Fig. 7).

[0067] As shown in FIG. 7 , the content playback device 10 acquires content and meta information (S110). Specifically, the content playback device 10 acquires content and meta information distributed by the content distribution device 30. In the following description, the content includes an unprocessed audio signal, an output audio signal, and a video or still image signal. The content playback device 10 can select either the unprocessed audio signal or the output audio signal and play back sound based on the selected audio signal. Furthermore, the audio mode described below refers to, for example, the audio playback method used by the content playback device 10. In the following description, a mode that plays back sound based on an unprocessed audio signal is referred to as an "unprocessed audio mode," and a mode that plays back sound based on an output audio signal is referred to as a "processed audio mode." However, the audio mode is not limited to this example and can be defined arbitrarily.

[0068] After step S110, if the raw sound mode is selected, the content playback device 10 executes playback of raw content (S111). Specifically, the content playback device 10 plays back the raw content among the content acquired in step S110. Here, the content playback device 10 may perform demultiplexing of the content (file), decoding of encoded data, or a combination thereof. As an example, the content playback device 10 outputs sound based on the raw audio signal from the audio output device 22 and displays video or still images on the display 21. This allows the user to listen to the sound based on the raw audio signal while viewing video or still images synchronized with the sound. As an example, the content playback device 10 displays the screen SC10 of FIG. 8 on the display 21.

[0069] The screen SC10 includes an object A10a. The object A10a displays information about the content being played. As an example, the object A10a displays at least one of the following: - Information for identifying the content being played (e.g., the content name, the channel name); - Information indicating that the audio mode is the unprocessed audio mode; - The user's score status. The object A10a may be displayed constantly, or may be displayed in response to a predetermined trigger (e.g., a channel change, an audio mode change, or a change between multiple pieces of content being played consecutively) and then displayed for a limited period of time. Note that the method of presenting information about the content being played is not limited to the example of FIG. 8. For example, the content playback device 10 may present information about the content being played to the user by a voice announcement or by illuminating an LED.

[0070] When displaying the user's score status, the content playback device 10 records the user's content viewing history and calculates the user's score status at any given time by referring to the record. As an example, the content playback device 10 may calculate the cumulative score over a target period (i.e., the change in cumulative score over time) by accumulating scores corresponding to each of multiple viewing histories. Alternatively, if a target score for the user over a target period is set, the content playback device 10 may calculate the ratio of the cumulative score to the target score as the user's achievement or lack of achievement. The target score corresponds to a standard for the score (i.e., the sounds that should be listened to) that the user should achieve within the target period to improve cognitive function. The content playback device 10 may calculate the achievement level at a specific point in time, or may calculate the achievement level over a target period (i.e., the change in achievement level over time).

[0071] After step S110, if the processed sound mode is selected, the content playback device 10 executes playback of the processed content (S112). Specifically, the content playback device 10 plays back the processed content among the content acquired in step S110. Here, the content playback device 10 may perform demultiplexing of the content (file) (dividing the multiplexed content), decoding of the encoded data, or a combination thereof. As an example, the content playback device 10 outputs sound based on the output acoustic signal from the acoustic output device 22 and displays a video or still image on the display 21. This allows the user to listen to the sound based on the output acoustic signal while viewing a video or still image synchronized with the sound. As an example, the content playback device 10 displays the screen SC11 of FIG. 9 on the display 21.

[0072] The screen SC11 includes an object A11a. The object A11a displays information about the content being played. As an example, the object A11a displays at least one of the following: - Information for identifying the content being played (e.g., the content name, the channel name); - Information indicating that the audio mode is a processed sound mode; - Content meta information (e.g., the score corresponding to the content); - User score status. The object A11a may be displayed constantly, or may be displayed in response to a predetermined trigger (e.g., a channel change, an audio mode change, or a change between multiple pieces of content being played consecutively) and then displayed for a limited period of time. Furthermore, the content meta information may be presented as information separate from the content, such as a program guide (including an EPG (Electronic Program Guide)) or data broadcasting.

[0073] When the content playback device 10 detects a switch to the processed sound mode during playback of the unprocessed content (S111), the content playback device 10 executes a mode switch (S113). For example, when an input device receives an instruction to switch to the processed sound mode from a user, the content playback device 10 executes a switch to the processed sound mode.

[0074] Similarly, when the content playback device 10 detects a switch to the raw sound mode during playback of the processed content (S112), the content playback device 10 executes a mode switch (S113). For example, when the input device receives an instruction to switch to the raw sound mode from the user, the content playback device 10 executes a switch to the raw sound mode.

[0075] The content playback process in Fig. 7 ends when, for example, one of the following conditions is met: - The content to be played back is switched. - The content being played back has finished. - The content playback process in Fig. 7 has ended due to another process or an external instruction. - The user has performed an operation to end the content playback process in Fig. 7. - The content playback device 10 has entered a predetermined state (for example, power loss). - A predetermined date and time has arrived. - A predetermined time has passed since a predetermined event (for example, startup of the content playback device 10 or start of execution of the content playback process in Fig. 7).

[0076] (4) Summary As described above, the content distribution device 30 of this embodiment performs modulation processing, including amplitude modulation, on an audio signal to generate an audio signal (i.e., an output audio signal) having an amplitude change corresponding to the frequency of gamma waves, and outputs content including the audio signal together with corresponding meta information. By referring to the output meta information, the user of the content playback device 10 can easily determine the content to be played or the viewing style of the content.

[0077] The content distribution device 30 may perform modulation processing on the audio signal included in the content so that the score corresponding to the content is equal to or greater than a reference value. This allows the content playback device 10 to obtain a score equal to or greater than the reference value by viewing the content without the user being particularly conscious of the content being played.

[0078] The content playback device 10 of this embodiment acquires meta information corresponding to content including an audio signal (i.e., an output audio signal) whose amplitude changes correspond to the frequency of gamma waves, and controls playback of the content based on the meta information. This allows a user to understand the content's meta information and view processed content without any special knowledge. Furthermore, as part of the control, the content playback device 10 may display information based on the meta information corresponding to the content on a screen displaying images included in the content. This allows a user to easily understand the content's meta information.

[0079] The meta information may include at least one of information indicating whether or not modulation processing is applied, information indicating details of the modulation processing, and information indicating a score determined based on the details of the modulation processing, which allows appropriate playback processing to be performed on the content and allows the user to understand the cognitive function improvement effect that can be expected from viewing the processed content.

[0080] The output acoustic signal may have an amplitude change corresponding to a frequency between 35 Hz and 45 Hz, inclusive, which can induce gamma waves in the brain of the user of the content playback device 10 and improve cognitive function.

[0081] (5) Modifications A modification of this embodiment will be described.

[0082] (5-1) Modification 1 Modification 1 will be described below. Modification 1 is an example in which the content playback device modulates the audio signal.

[0083] (5-1-1) Information Processing The information processing of the first modification will be described.

[0084] (5-1-1-1) Content Distribution Processing The following describes the content distribution processing of Modification 1. FIG.

[0085] The content distribution process in Fig. 10 is realized by the processor 32 of the content distribution device 30 reading and executing a program stored in the storage device 31. The content distribution process in Fig. 10 can be started when the same start conditions as those for the content distribution process of the present embodiment are met.

[0086] As shown in FIG. 10, the content distribution device 30 acquires an input sound signal (S130) in the same manner as in FIG.

[0087] After step S131, the content distribution device 30 generates meta information (S232). Specifically, the content distribution device 30 generates meta information according to the modulation process recommended to be performed in the content reproduction device 10. The meta information may include the information described in this embodiment. The modulation process recommended to be performed in the content reproduction device 10 may be determined based on an input operation by a creator or provider of content corresponding to the input acoustic signal, an external instruction, or an algorithm. However, the content distribution device 30 may perform modulation processing based on the modulation information included in the meta information in order to calculate the score.

[0088] After step S232, the content distribution device 30 executes content distribution (S233). Specifically, the content distribution device 30 distributes content based on the input audio signal acquired in step S130 (which may not include processed content) to the content playback device 10 along with the meta information generated in step S232. As an example, the content distribution device 30 may generate a content file in a predetermined format by multiplexing an unprocessed audio signal (e.g., the input audio signal) and the meta information. A content viewer can select whether to listen to sound based on the unprocessed audio signal or sound based on an audio signal amplitude-modulated by the content playback device 10. The content distribution device 30 may also include an image signal (moving image signal or still image signal) in the content file. Furthermore, the content distribution device 30 may perform encoding (compression) processing before multiplexing various types of information. The content distribution device 30 terminates the content distribution processing of FIG. 10 at step S233. The content distribution device 30 may perform the content distribution process of FIG. 10 all at once for an input audio signal having a certain playback period (e.g., one piece of music content), or may repeatedly perform the content distribution process of FIG. 10 for each predetermined playback section of the input audio signal (e.g., every 100 ms). Alternatively, the content distribution device 30 may continuously perform modulation processing on the input audio signal, such as modulation using analog signal processing, and output the modulated audio signal. The content distribution process shown in FIG. 10 may be terminated in response to a specific termination condition (e.g., the passage of a certain amount of time, an operation by the creator or provider of the content or the user of the content playback device 10, or the output history of the modulated sound reaching a predetermined state).

[0089] (5-1-1-2) Content Playback Processing The following describes the content playback processing of Modification 1. FIG.

[0090] The content playback process of FIG. 11 can be started when the same start conditions as those of the content playback process of this embodiment (FIG. 7) are met.

[0091] As shown in Fig. 11 , the content playback device 10 acquires content and meta information (S110), similar to Fig. 7 . In the following description, the content includes an unprocessed audio signal and a video or still image signal. The content playback device 10 can select either the unprocessed audio signal or an audio signal (output audio signal) obtained by amplitude-modulating at least a portion of the unprocessed audio signal, and play back sound based on the selected audio signal.

[0092] After step S110, if the raw sound mode is selected, the content reproducing device 10 reproduces the raw content (S111) in the same manner as in FIG.

[0093] After step S110, if the processed sound mode is selected, the content playback device 10 performs modulation of the audio signal (S212). Specifically, the content playback device 10 generates an output audio signal by at least partially amplitude modulating the raw audio signal included in the content acquired in step S110. Here, the content playback device 10 may perform demultiplexing of the content (file), decoding of encoded data, or a combination thereof.

[0094] As a first example of modulating the audio signal (S212), the content playback device 10 generates an intermediate audio signal based on the raw audio input signal. The content playback device 10 may determine a method for generating the intermediate audio signal by referring to the meta information acquired in step S110.

[0095] The content reproduction device 10 selects a target signal from the plurality of sound signals included in the intermediate sound signal. The content reproduction device 10 may determine which sound signal to select as the target signal by referring to meta information.

[0096] The content reproduction device 10 performs amplitude modulation on the selected target signal. The content reproduction device 10 may determine at least one of a modulation function and a modulation depth by referring to meta information.

[0097] The content reproduction device 10 generates an output acoustic signal based on the asymmetric signal and the modulated target signal. The technique for generating the output acoustic signal based on the asymmetric signal and the modulated target signal may be the same as that of the present embodiment.

[0098] In a second example of the modulation of an audio signal (S212), the raw audio signal includes multiple audio signals with different characteristics. The content playback device 10 selects one or more audio signals to which amplitude modulation is to be applied from the multiple audio signals included in the raw audio signal. The second example of the modulation of an audio signal (S212) can be understood by appropriately replacing the "intermediate audio signal" with the "raw audio signal" in the description of the first example above.

[0099] In the third example of the modulation of the acoustic signal (S212), the content reproduction device 10 performs amplitude modulation on the raw acoustic signal. The amplitude modulation on the raw acoustic signal is similar to the amplitude modulation on the target signal described in the first example of the modulation of the acoustic signal (S212).

[0100] The content reproduction device 10 generates an output audio signal based on the modulated audio signal. The technique for generating the output audio signal based on the modulated audio signal may be the same as that of the present embodiment.

[0101] After step S212, the content playback device 10 executes playback of the processed content (S213). Specifically, the content playback device 10 plays the output acoustic signal (processed content) generated in step S212. As an example, the content playback device 10 outputs sound based on the output acoustic signal from the acoustic output device 22 and displays a video or still image on the display 21. This allows the user to view a video or still image synchronized with the sound while listening to the sound based on the output acoustic signal. As an example, the content playback device 10 displays screen SC11 of FIG. 9 on the display 21.

[0102] When the content playback device 10 detects a switch to the processed sound mode during playback of the unprocessed content (S111), the content playback device 10 modulates the acoustic signal (S212). For example, when the input device receives an instruction to switch to the processed sound mode from the user, the content playback device 10 detects the switch to the processed sound mode.

[0103] Similarly, when the content playback device 10 detects a switch to the raw sound mode during modulation of the acoustic signal (S212) or playback of the processed content (S213), the content playback device 10 executes playback of the raw content (S111). For example, when the input device receives an instruction to switch to the raw sound mode from the user, the content playback device 10 detects a switch to the raw sound mode.

[0104] The content playback process of FIG. 11 can be terminated when the same termination condition as in the content playback process of this embodiment is met.

[0105] (5-1-2) Summary As described above, the content playback device 10 of Modification 1 performs modulation processing on the acoustic signal included in the content distributed from the content distribution device 30 based on modulation information included in the meta information. This allows the user of the content playback device 10 to view the processed content even if the content distribution device 30 does not distribute the processed content. Therefore, Modification 1 is useful, for example, when the capacity of the transmission path for content distribution is limited.

[0106] In the above description of the first modification, an example has been shown in which the content playback device 10 dynamically switches modulation processes during playback of content. However, this is not limiting, and the content playback device 10 may perform modulation processes on a content-by-content basis based on meta information. For example, the content playback device 10 may determine details of the modulation process to be performed in step S212 so that the score of the modulated content is equal to or greater than a reference value.

[0107] (5-2) Modification 2 Modification 2 will be described below. Modification 2 is an example in which the content playback device 10 controls the content recommended to the user and the mode in which the content is played back.

[0108] (5-2-1) Content Playback Processing The following describes the content playback processing of Modification 2. FIG.

[0109] The content playback process of FIG. 12 can be started when the same start conditions as those of the content playback process of this embodiment (FIG. 7) are met.

[0110] As shown in FIG. 12 , the content playback device 10 acquires meta information (S310). Specifically, the content playback device 10 acquires meta information of multiple playable contents. As a first example of the meta information acquisition (S310), the content playback device 10 acquires meta information distributed by the content distribution device 30. As a second example of the meta information acquisition (S310), the content playback device 10 acquires meta information by referring to an information source (e.g., EPG) in which the meta information of the content is stored. As a third example of the meta information acquisition (S310), the content playback device 10 acquires meta information by demultiplexing content stored in the storage device 11. As a fourth example of the meta information acquisition (S310), the content playback device 10 acquires meta information input by the user.

[0111] After step S310, the content playback device 10 selects content and a mode (S311). Specifically, the content playback device 10 selects content to recommend to the user and a mode for playing the content based on the meta information acquired in step S310. As an example, the content playback device 10 may select content or a mode based on at least one of the following user information: User attributes (e.g., age, gender, hometown, location, and language used); User operation history (e.g., browsing history of sites for elderly people, operation history indicating a suspected dementia tendency); User content viewing history (e.g., whether the user viewed enough content containing sound based on an output acoustic signal on that day); User questionnaire responses; and User dementia test results. The content playback device 10 may estimate, for example, the user's preferences (e.g., genre, artist, etc.) based on the user information, and select content or a mode according to the preferences. For example, the content reproduction device 10 may preferentially select content that the user likes, or may reduce the frequency with which the content that the user likes is reproduced in the processed sound mode.

[0112] Furthermore, the content playback device 10 may select content and a mode based on the score of each content so that the user can achieve a goal of obtaining a score. For example, the content playback device 10 may preferentially select content with a high score or content with a score exceeding a predetermined threshold.

[0113] In step S311, the content playback device 10 may select only one piece of content to be viewed by the user immediately and a mode for playing the content, or may select a combination of multiple pieces of content to be viewed by the user in the future (i.e., a playlist) and a mode for playing the content. For example, the content playback device 10 may create a playlist so that the total score of the content included in the playlist is equal to or greater than a reference value. The reference value may be set for each user or may be common to multiple users. The content playback device 10 may obtain the reference value from an external device, read it from the storage device 11, or determine it based on user input. Note that the content and mode selection in S311 may be performed automatically by the content playback device 10 based on meta information, or may be performed in response to a user operation on candidates proposed by the content playback device 10 based on meta information.

[0114] After step S311, the content playback device 10 executes content acquisition (S312). Specifically, the content playback device 10 acquires the content selected in step S311. As a first example of content acquisition (S312), the content playback device 10 acquires content distributed by the content distribution device 30. As a second example of content acquisition (S312), the content playback device 10 acquires content stored in the storage device 11.

[0115] After step S312, if the raw sound mode is selected, the content playback device 10 executes playback of raw content (S313). Specifically, the content playback device 10 plays back the raw content among the content acquired in step S312. Here, the content playback device 10 may perform demultiplexing of the content (file), decoding of encoded data, or a combination thereof. As an example, the content playback device 10 outputs sound based on the raw audio signal from the audio output device 22 and displays video or still images on the display 21. This allows the user to listen to the sound based on the raw audio signal while viewing video or still images synchronized with the sound. As an example, the content playback device 10 displays the screen SC10 of FIG. 8 on the display 21.

[0116] After step S312, if the processed sound mode is selected, the content playback device 10 performs modulation of the audio signal (S314). Specifically, the content playback device 10 generates an output audio signal by at least partially amplitude modulating the raw audio signal included in the content acquired in step S312. Here, the content playback device 10 may perform demultiplexing of the content (file), decoding of encoded data, or a combination thereof. However, if the content includes an output audio signal, the content playback device 10 may omit modulation of the audio signal (S314).

[0117] As a first example of modulating the audio signal (S314), the content playback device 10 generates an intermediate audio signal based on the raw audio input signal. The content playback device 10 may determine a method for generating the intermediate audio signal by referring to the meta information acquired in step S310 (meta information corresponding to the content acquired in step S312).

[0118] The content reproduction device 10 selects a target signal from the plurality of sound signals included in the intermediate sound signal. The content reproduction device 10 may determine which sound signal to select as the target signal by referring to meta information.

[0119] The content reproduction device 10 performs amplitude modulation on the selected target signal. The content reproduction device 10 may determine at least one of a modulation function and a modulation depth by referring to meta information.

[0120] The content reproduction device 10 generates an output acoustic signal based on the asymmetric signal and the modulated target signal. The technique for generating the output acoustic signal based on the asymmetric signal and the modulated target signal may be the same as that of the present embodiment.

[0121] In a second example of modulation of an audio signal (S314), the raw audio signal includes multiple audio signals with different characteristics. The content playback device 10 selects one or more audio signals to which amplitude modulation is to be applied from the multiple audio signals included in the raw audio signal. The second example of modulation of an audio signal (S314) can be understood by appropriately replacing the "intermediate audio signal" with the "raw audio signal" in the description of the first example above.

[0122] In the third example of the modulation of the acoustic signal (S314), the content reproduction device 10 performs amplitude modulation on the raw acoustic signal. The amplitude modulation on the raw acoustic signal is similar to the amplitude modulation on the target signal described in the first example of the modulation of the acoustic signal (S314).

[0123] The content reproduction device 10 generates an output audio signal based on the modulated audio signal. The technique for generating the output audio signal based on the modulated audio signal may be the same as that of the present embodiment.

[0124] After step S314, the content playback device 10 executes playback of the processed content (S315). Specifically, the content playback device 10 plays the output audio signal (processed content) generated in step S314. However, if the content acquired in step S312 includes an output audio signal, the content playback device 10 can play the output audio signal included in the content. As an example, the content playback device 10 outputs sound based on the output audio signal from the audio output device 22 and displays a video or still image on the display 21. This allows the user to view a video or still image synchronized with the sound while listening to the sound based on the output audio signal. As an example, the content playback device 10 displays the screen SC11 of FIG. 9 on the display 21.

[0125] The content playback device 10 repeats the processes of steps S312 to S313 or steps S312, S314 to S315 until playback of the content selected in step S311 is completed. When playback of the content selected in step S311 is completed, the content playback device 10 may re-execute acquisition of meta information (S310) or selection of content and mode (S311), or may end the content playback process of FIG. 12.

[0126] The content playback process of FIG. 12 can be terminated when the same termination condition as in the content playback process of this embodiment is met.

[0127] (5-2-2) Summary As described above, the content playback device 10 of Modification 2 selects content to recommend to a user based on content meta information and user information. This allows the user to view content that is appropriate from the perspective of preferences and cognitive function improvement effects, without having to actively select content to play.

[0128] Furthermore, the content playback device 10 may generate a list (playlist) of one or more pieces of content to be played back such that the total score of the pieces of content included in the list is equal to or greater than a reference value. This allows the user to view a group of pieces of content that can achieve a score equal to or greater than a reference value without having to actively select the pieces of content to be played back.

[0129] (7) Other Modifications The storage device 11 may be connected to the content reproduction device 10 via a network. The display 21 may be integrated with the content reproduction device 10. The storage device 31 may be connected to the content distribution device 30 via a network.

[0130] Each step of the above information processing can be executed by either the content reproduction device 10 or the content distribution device 30. Some of the steps of the above information processing may be executed by an external device (for example, a server) not shown.

[0131] The above description shows an example in which the content playback device 10 is connected to one sound output device 22. The content playback device 10 may be connected to a plurality of sound output devices 22, and in this case, the content playback device 10 may be configured to be able to select which sound output device 22 to send the sound signal to.

[0132] The content reproduction device 10 may be equipped with a function for conducting a questionnaire or a cognitive function test (for example, a function for measuring cognitive function through voice dialogue with the user).

[0133] An algorithm for determining a method for generating an output audio signal (e.g., a modulation method, a combining ratio of two or more audio signals, a method for determining an audio signal to which amplitude modulation is applied, etc.), or a default method for generating an output audio signal, may be changed by updating the firmware of the content distribution device 30. The firmware is updated, for example, by the content distribution device 30 communicating with an external device (e.g., a server not shown).

[0134] Although the example in which the input sound signal is acquired from the sound source device 41 has been described, the input sound signal may be generated by receiving environmental sound using a microphone. The input sound signal may be read from the storage device 31 or a removable medium connected to the content distribution device 30. The sound source device 41 (including the sound source device 41 built into the content distribution device 30) may generate the input sound signal each time.

[0135] Although the above description has been given of an example in which an audio signal derived from an input audio signal is modulated, an output audio signal may also be generated based on the input audio signal and a modulated audio signal that is not derived from the input audio signal.

[0136] The above description has focused on an example in which the modulation function has a frequency of 35 Hz or more and 45 Hz or less. However, the modulation function used by the content playback device 10 or the content distribution device 30 is not limited to this, and any modulation function that affects the induction of gamma waves in the listener's brain may be used. For example, the modulation function may have a frequency of 25 Hz or more and 140 Hz or less. Furthermore, for example, the frequency of the modulation function may change over time, and the modulation function may partially have a frequency below 35 Hz or a frequency higher than 45 Hz.

[0137] In the above description, an example has been described in which content is distributed together with meta information. However, instead of distributing content together with meta information, the content may be recorded on a storage medium. In this case, the content distribution device may be interpreted as a content recording device. The content playback device can read the content and meta information from the storage medium, play the content, and perform control based on the meta information.

[0138] In the above description, an example in which the content distribution device 30 generates meta information has been mainly described. However, the present invention is not limited to this. For example, meta information may be set by a content creator, a broadcasting company, or a content viewer. The set meta information may be stored in a storage device or recording medium, and the content distribution device 30 may acquire the meta information from an external storage device or recording medium. In this case, the content distribution device 30 may acquire the content and the meta information separately, or may acquire the content to which meta information has been added. Furthermore, for example, the content distribution device 30 may determine the meta information based on an input by a user.

[0139] Furthermore, the meta information does not have to be distributed to the content reproduction device 10. For example, the meta information may be published on a web page, in a newspaper, in a magazine, or the like, or may be notified to a terminal used by a user (for example, a notification in an app or an email notification). In this case, the content reproduction device 10 may acquire the meta information by, for example, referring to an information source in which the meta information of the content is stored, or may acquire the meta information input by a user.

[0140] Furthermore, when the content distribution device 30 acquires additional information (for example, an ID3 tag in an MP3 file) along with the input audio signal, the content distribution device 30 may modify the additional information and output it to an external device together with the output audio signal.

[0141] In the present embodiment, an example has been described in which the content distribution device 30 distributes content including an unprocessed audio signal and an output audio signal. Here, the number of multiplexed audio signals of the content to be distributed may be determined arbitrarily. That is, output audio signals to which different modulation processes (e.g., modulation processes with different modulation functions or modulation depths) have been applied may be multiplexed and distributed. Furthermore, the content distribution device 30 may multiplex and distribute other audio signals in addition to the output audio signal and the unprocessed audio signal. For example, the content distribution device 30 may multiplex and distribute unprocessed audio in a first language, processed audio in the first language, unprocessed audio in a second language, and processed audio in the second language.

[0142] An amplitude-modulated audio signal (e.g., an audio signal corresponding to a beep, chirp, noise, or background music) may be synthesized into a period corresponding to a silent portion of the raw audio signal. This can improve the cognitive function of the user of the content playback device 10 without interfering with the listening of the original sound of the content. The synthesis of such an audio signal may be performed by the content distribution device 30 or the content playback device 10.

[0143] In the first modification, an example has been shown in which the content playback device 10 performs modulation processing. The content playback device 10 may perform modulation processing according to modulation information included in the meta information, or may perform modulation processing in response to a user instruction. As an example, the user may select a modulation setting (e.g., a modulation function or a modulation depth). In this case, the content playback device 10 may present information on recommended modulation settings to the user based on the modulation information included in the meta information.

[0144] In the second modification, an example has been described in which the content playback device 10 selects content recommended to the user and a mode in which the content is to be played back, and automatically controls the playback of the content in accordance with the selection result. However, the content or mode selected by the content playback device 10 may be changed by the user. This allows the user to decide the content to actually view or the mode in which the content is to be viewed based on their own will or preference, while referring to the selection result by the content playback device 10 as a basis for making a decision.

[0145] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the above-described embodiments. Furthermore, the above-described embodiments can be improved or modified in various ways without departing from the spirit of the present invention. Furthermore, the above-described embodiments and modifications can be combined.

[0146] 1: Cognitive function improvement system 10: Content playback device 11: Storage device 12: Processor 13: Input / output interface 14: Communication interface 21: Display 22: Sound output device 30: Content distribution device 31: Storage device 32: Processor 33: Input / output interface 34: Communication interface 41: Sound source device

Claims

1. A system having a content distribution device and a content playback device, The aforementioned content distribution device is A means for acquiring a modulated acoustic signal obtained by performing a modulation process including amplitude modulation on an acoustic signal, which includes a modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave, and related information relating to the modulation process performed to generate the modulated acoustic signal included in the content. Having means for distributing the aforementioned content and the aforementioned related information, The aforementioned content playback device is Means for acquiring the content and related information distributed by the content distribution device, The system includes means for controlling the playback of the aforementioned content based on the aforementioned related information, system.

2. A system having a content distribution device and a content playback device, The aforementioned content distribution device is Means for obtaining content containing an acoustic signal, and related information relating to a modulation process for generating a modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave from the acoustic signal contained in the content, Having means for distributing the aforementioned content and the aforementioned related information, The aforementioned content playback device is Means for acquiring the content and related information distributed by the content distribution device, The system includes means for generating an output audio signal for playback of the content by performing modulation processing, including amplitude modulation, on the audio signal contained in the content based on the related information. system.

3. Content including a modulated acoustic signal obtained by performing a modulation process including amplitude modulation on an acoustic signal, the modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave, and an acquisition means for acquiring related information relating to the modulation process performed to generate the modulated acoustic signal included in the content, The system includes a distribution means for distributing the content and related information acquired by the acquisition means via at least one of a broadcast transmission line and an information communication transmission line. Processing device.

4. A means for obtaining a reference value for a score determined based on the content of the modulation process, The system includes a generation means for generating a modulated acoustic signal by performing a modulation process on the acoustic signal based on a reference value obtained by the reference value acquisition means, with the content determined based on the reference value. The apparatus according to claim 3.

5. The content distributed by the distribution means includes the acoustic signal and the modulated acoustic signal, The apparatus according to claim 3.

6. The distribution means distributes one of the acoustic signal and the modulated acoustic signal as the main audio of the content, and the other as the secondary audio of the content. The apparatus according to claim 5.

7. An acquisition means for acquiring content including an acoustic signal and related information relating to a modulation process for generating a modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave from the acoustic signal included in the content, The system includes a distribution means for distributing the content and related information acquired by the acquisition means via at least one of a broadcast transmission line and an information communication transmission line. Processing device.

8. A means for acquiring, via at least one of a broadcast transmission line and an information communication transmission line, content including a modulated acoustic signal obtained by performing a modulation process including amplitude modulation on an acoustic signal, the modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave, and related information relating to the modulation process performed to generate the modulated acoustic signal included in the content, The system includes a control means that controls the playback of the aforementioned content based on the aforementioned related information, Processing device.

9. The control by the control means for playback of the content includes control for displaying information based on the related information on the display screen for playback of the content. The apparatus according to claim 8.

10. The system has means for obtaining user information relating to at least one of the following: user attributes, operation history, and viewing history. The control by the control means regarding the playback of the content includes control that prompts the user to view the content based on the user information and the related information. The apparatus according to claim 8.

11. The control by the control means for playback of the content includes a control for generating a list of one or more content items to be played back, wherein the list is generated such that the sum of the scores determined based on the content of the modulation process performed to generate the modulated sound signals included in the content in the list is equal to or greater than a predetermined reference value. The apparatus according to claim 8.

12. A means for acquiring content including an acoustic signal and related information relating to a modulation process for generating a modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave from the acoustic signal included in the content, via at least one of a broadcast transmission line and an information communication transmission line, The system includes means for generating an output audio signal for playback of the content by performing modulation processing, including amplitude modulation, on the audio signal contained in the content based on the related information. Processing device.

13. The aforementioned related information includes at least one of the following: information indicating whether or not modulation processing is applied; information indicating the content of the modulation processing; and information indicating the score determined based on the content of the modulation processing. The apparatus according to any one of claims 3 to 12.

14. The frequency of the gamma wave is between 35 Hz and 45 Hz. The apparatus according to any one of claims 3 to 12.

15. A modulated acoustic signal obtained by performing a modulation process including amplitude modulation on an acoustic signal, the modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave, and a content obtained, and related information relating to the modulation process performed to generate the modulated acoustic signal included in the content, The acquired content and related information are distributed via at least one of a broadcast transmission line and an information communication transmission line. Processing method.

16. Obtaining content including an acoustic signal and related information relating to a modulation process for generating a modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave from the acoustic signal contained in the content, The acquired content and related information are distributed via at least one of a broadcast transmission line and an information communication transmission line. Processing method.

17. Content including a modulated acoustic signal obtained by performing a modulation process including amplitude modulation on an acoustic signal, the modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave, and related information relating to the modulation process performed to generate the modulated acoustic signal included in the content, are obtained via at least one of a broadcast transmission line and an information communication transmission line. Control over the playback of the aforementioned content is performed based on the aforementioned related information. Processing method.

18. Content including an acoustic signal and related information relating to a modulation process for generating a modulated acoustic signal having an amplitude change corresponding to the frequency of a gamma wave from the acoustic signal included in the content are obtained via at least one of a broadcast transmission line and an information communication transmission line, By performing modulation processing, including amplitude modulation, on the acoustic signals contained in the content based on the related information, an output acoustic signal for playback of the content is generated. Processing method.

19. A program for causing a computer to execute the processing method described in any one of claims 15 to 18.