Attention function improvement system, fluency improvement system, executive function improvement system, creativity improvement system, cognitive function improvement system, and program

Abstract

This technology provides a way to positively influence human brain function through auditory stimulation at specific intervals. [Solution] The attention function improvement system comprises means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, and means for improving the attention function of a subject by presenting an auditory stimulus based on the acoustic signal to the subject.

Description

Technical Field

[0001] The present disclosure relates to an attention function improvement system, a fluency improvement system, a performance function improvement system, a creativity improvement system, a cognitive function improvement system, and a program.

Background Art

[0002] There is a research report that when a pulsed sound stimulus is perceived by an Alzheimer's disease model mouse at a frequency of about 40 times per second and gamma waves are induced in the mouse's brain, it is effective in improving spatial memory and recognition memory. (See Non-Patent Document 1). Gamma waves refer to those among the nerve oscillations captured by electrophysiological methods such as electroencephalograms and magnetoencephalograms of the periodic nerve activities of the cerebral cortex, whose frequencies are included in the gamma band (25 - 140 Hz).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, it has not been verified what effects can be obtained when a sound stimulus of a specific period is given to humans.

[0005] An object of the present disclosure is to provide a technology that positively affects human brain functions by a sound stimulus of a specific period.

Means for Solving the Problems

[0006] An attention function improvement system according to one aspect of the present disclosure comprises means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, and means for improving the attention function of a subject by presenting an auditory stimulus based on the acoustic signal to the subject. [Brief explanation of the drawing]

[0007] [Figure 1] This is a block diagram showing the configuration of the acoustic system of this embodiment. [Figure 2] This is a block diagram showing the configuration of the signal processing device of this embodiment. [Figure 3] This is an explanatory diagram of one aspect of this embodiment. [Figure 4] This is an explanatory diagram of one aspect of this embodiment. [Figure 5] This figure shows the amplitude waveform of the first example of the output acoustic signal. [Figure 6] This figure shows the amplitude waveform of a second example of the output acoustic signal. [Figure 7] This figure shows the amplitude waveform of a third example of the output acoustic signal. [Figure 8] This figure shows the waveform of the fourth example of the output acoustic signal. [Figure 9] This figure shows the waveform of the fifth example of the output acoustic signal. [Figure 10] This figure shows the waveform of the stimulus sound used in the experiment of Example 1. [Figure 11] This figure shows the results of the experiment in Example 1. [Figure 12] This figure shows the results of the category fluency task in Example 2. [Figure 13] This figure shows the results of the idea fluency task in Example 2. [Figure 14] This figure shows the results of the sustained attention task in Example 3. [Figure 15] This figure shows the results of the sustained attention task in Example 3. [Figure 16] This diagram shows the overall flow of acoustic signal processing by the signal processing device of this embodiment. [Modes for carrying out the invention]

[0008] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In the drawings used to illustrate the embodiment, the same reference numerals are generally used for identical components, and repeated descriptions thereof will be omitted.

[0009] (1) Configuration of the sound system The configuration of the sound system will now be described. Figure 1 is a block diagram showing the configuration of the sound system in this embodiment.

[0010] As shown in Figure 1, the acoustic system 1 comprises a signal processing device 10, an acoustic output device 30, and a sound source device 50.

[0011] The signal processing device 10 and the sound source device 50 are connected to each other via a predetermined interface capable of transmitting acoustic signals. The interface may be, for example, SPDIF (Sony Philips Digital Interface), HDMI (High-Definition Multimedia Interface), a pin connector (RCA pin), or an audio interface for headphones. The interface may also be a wireless interface using Bluetooth (registered trademark). The signal processing device 10 and the sound output device 30 are similarly connected to each other via a predetermined interface. The acoustic signal in this embodiment includes either an analog signal or a digital signal, or both.

[0012] The signal processing device 10 performs acoustic signal processing on the input acoustic signal acquired from the sound source device 50. The acoustic signal processing by the signal processing device 10 includes, for example, modulation processing of the acoustic signal or processing of adding an auxiliary acoustic signal having periodic fluctuations to the input acoustic signal. Further, the acoustic signal processing by the signal processing device 10 may include conversion processing (for example, separation, extraction, or synthesis) of the acoustic signal. Furthermore, the acoustic signal processing by the signal processing device 10 may further include amplification processing of the acoustic signal similar to, for example, an AV amplifier. Also, the signal processing device 10 may perform acoustic signal processing to independently generate an acoustic signal having periodic fluctuations without acquiring the input acoustic signal from the sound source device 50. The signal processing device 10 sends the output acoustic signal generated by the acoustic signal processing to the acoustic output device 30. The signal processing device 10 is an example of an information processing device.

[0013] The acoustic output device 30 presents an acoustic stimulus based on the output acoustic signal to the listener by generating a sound corresponding to the output acoustic signal acquired from the signal processing device 10. The acoustic output device 30 is, for example, a loudspeaker (which may include a speaker with a built-in amplifier (powered speaker)), headphones, or earphones. The acoustic output device 30 can also be configured as a single device together with the signal processing device 10. Specifically, the signal processing device 10 and the acoustic output device 30 can be implemented in a TV, radio, music player, AV amplifier, speaker, headphones, earphones, smartphone, or PC. The subject (listener) presented with the acoustic stimulus by the acoustic output device 30 can expect at least one of improvement in the attention function, improvement in fluency, improvement in the execution function, improvement in creativity, and improvement in the cognitive function, as will be described later. That is, the signal processing device 10 and the acoustic output device 30 constitute an attention function improvement system, a fluency improvement system, an execution function improvement system, a creativity improvement system, and a cognitive function improvement system.

[0014] The sound source device 50 sends the input acoustic signal to the signal processing device 10. The sound source device 50 is, for example, a TV, radio, music player, smartphone, PC, electronic musical instrument, telephone, game machine, gaming machine, or a device that conveys an acoustic signal by broadcasting or information communication.

[0015] (1-1) Configuration of the signal processing device The configuration of the signal processing device will be described. FIG. 2 is a block diagram showing the configuration of the signal processing device of the present embodiment.

[0016] As shown in FIG. 2, the signal processing device 10 includes a storage device 11, a processor 12, an input / output interface 13, and a communication interface 14. The signal processing device 10 is connected to the display 21.

[0017] The storage device 11 is configured to store programs and data. The storage device 11 is, for example, a combination of a ROM (Read Only Memory), a RAM (Random Access Memory), and a storage (e.g., flash memory or 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.

[0018] The program includes, for example, the following programs. · Program of the OS (Operating System) · Program of an application that executes information processing

[0019] The data includes, for example, the following data. · Database referred to in information processing · Data obtained by executing information processing (i.e., the execution result of information processing)

[0020] The processor 12 is a computer that realizes the functions of the signal processing device 10 by reading and executing the programs stored in the storage device 11. Note that at least a part of the functions of the signal processing device 10 may be realized 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)

[0021] The input / output interface 13 is configured to receive user instructions from an input device connected to the signal processing device 10 and to output information to an output device connected to the signal processing device 10. The input device may be, for example, a sound source device 50, physical buttons, a keyboard, a pointing device, a touch panel, or a combination thereof. The output device may be, for example, a display 21, an audio output device 30, or a combination thereof.

[0022] 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, and a filter.

[0023] The communication interface 14 is configured to control communication between the signal processing device 10 and an external device (for example, an acoustic output device 30 or a sound source device 50).

[0024] The display 21 is configured to display images (still images or moving images). The display 21 is, for example, a liquid crystal display or an organic EL display.

[0025] (2) One embodiment One aspect of this embodiment will now be described. Figures 3 and 4 are explanatory diagrams of one aspect of this embodiment.

[0026] (2-1) Overview of the Embodiment Figure 3 shows an example in which the signal processing device 10 generates an output acoustic signal by performing acoustic signal processing on the input acoustic signal acquired from the sound source device 50. As shown in Figure 3, the signal processing device 10 acquires an input acoustic signal from the sound source device 50. The signal processing device 10 generates an output acoustic signal by performing acoustic signal processing on the input acoustic signal.

[0027] The first example of acoustic signal processing is the modulation of an input acoustic signal. Modulation is amplitude modulation using a modulation function with frequencies corresponding to gamma waves (e.g., frequencies between 35Hz and 45Hz). This adds amplitude changes (periodic fluctuations in volume) corresponding to the above frequencies to the acoustic signal. Applying different modulation functions to the same input acoustic signal will result in different amplitude waveforms for the output acoustic signal. Examples of amplitude waveforms will be discussed later.

[0028] A second example of acoustic signal processing involves adding an auxiliary acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves to an input acoustic signal. As a result, the resulting acoustic signal also has periodic fluctuations corresponding to the frequency of gamma waves. The auxiliary acoustic signal is, for example, a signal having pulses with a period corresponding to the frequency of gamma waves, but is not limited to this. For example, the auxiliary acoustic signal may be a sine wave corresponding to the frequency of gamma waves, or it may be generated by applying amplitude modulation according to the frequency of gamma waves to any acoustic signal such as noise or music.

[0029] The signal processing device 10 sends the output acoustic signal to the acoustic output device 30. The acoustic output device 30 presents an acoustic stimulus based on the output acoustic signal to the subject (user US1) by generating an output sound corresponding to the output acoustic signal.

[0030] User US1 (an example of a "hearing person") receives auditory stimuli presented by the acoustic output device 30. User US1 may be, for example, a dementia patient, a person at risk of dementia, or a healthy person who expects improvement in brain function. As mentioned above, the output acoustic signal is based on an output acoustic signal having periodic fluctuations between 35 Hz and 45 Hz. Therefore, by listening to the sound emitted from the acoustic output device 30, User US1's brain function can be positively affected.

[0031] Figure 4 shows an example in which the signal processing device 10 generates an output acoustic signal by performing acoustic signal processing that independently generates an acoustic signal having periodic fluctuations, without acquiring an input acoustic signal from the sound source device 50. The acoustic signal generated by the acoustic signal processing is, for example, a signal having pulses with a period corresponding to the frequency of gamma waves (e.g., a frequency between 35 Hz and 45 Hz), but is not limited to this. For example, the auxiliary acoustic signal may be a sine wave corresponding to the frequency of gamma waves.

[0032] The signal processing device 10 sends an output acoustic signal to the acoustic output device 30. The acoustic output device 30 presents an auditory stimulus based on the output acoustic signal to the subject (user US1) by generating an output sound corresponding to the output acoustic signal. User US1 receives the auditory stimulus presented by the acoustic output device 30. The output acoustic signal has a periodic fluctuation between 35 Hz and 45 Hz. Therefore, by listening to the sound emitted from the acoustic output device 30, user US1's brain function can be positively affected.

[0033] (2-2) First example of an output acoustic signal Figure 5 shows the amplitude waveform of the first example of an output acoustic signal generated by applying amplitude modulation to the input acoustic signal according to the frequency of the gamma wave. If A(t) is the modulation function used to modulate the input acoustic signal, X(t) is the function representing the waveform of the input acoustic signal before modulation, and Y(t) is the function representing the waveform of the output acoustic signal after modulation, then Y(t) = A(t)·X(t) This is the result.

[0034] In the first example, the modulation function has an inverse sawtooth waveform at 40 Hz. The input acoustic signal is a homogeneous sound signal with a constant frequency higher than 40 Hz and constant sound pressure. As a result, the envelope of the amplitude waveform of the output acoustic signal takes on a shape that follows an inverse sawtooth wave.

[0035] Specifically, as shown in Figure 5, the amplitude waveform of the output acoustic signal has amplitude changes corresponding to the frequency of the gamma wave, and the rising portion C and falling portion B of the envelope A of the amplitude waveform are asymmetric (i.e., the rising time length and the falling time length are different).

[0036] In the first example, the rising edge of envelope A of the amplitude waveform of the output acoustic signal is steeper than the falling edge. In other words, the time required for the rising edge is shorter than the time required for the falling edge. The amplitude value of envelope A rises sharply to its maximum amplitude and then gradually decreases over time. That is, envelope A has an inverse sawtooth wave pattern.

[0037] (2-3) Second example of output acoustic signal A second example of the output acoustic signal will be described. Figure 6 shows the amplitude waveform of the second example of the output acoustic signal, which is generated by applying amplitude modulation according to the gamma wave frequency to the input acoustic signal.

[0038] In the second example, the modulation function has a sawtooth waveform at 40 Hz. The input acoustic signal is a homogeneous sound signal with a constant frequency higher than 40 Hz and constant sound pressure. As a result, the envelope of the amplitude waveform of the output acoustic signal takes on a shape that follows a sawtooth wave.

[0039] Specifically, as shown in Figure 6, the falling edge of envelope A of the amplitude waveform of the output acoustic signal in the second example is steeper than the rising edge. In other words, the time required for the falling edge is shorter than the time required for the rising edge. The amplitude value of envelope A gradually increases over time to its maximum amplitude, and then drops sharply. That is, envelope A has a sawtooth wave shape.

[0040] (2-4) Third example of an output acoustic signal A third example of the output acoustic signal will be described. Figure 7 shows the amplitude waveform of the third example of the output acoustic signal, which is generated by applying amplitude modulation according to the gamma wave frequency to the input acoustic signal.

[0041] In the third example, the modulation function has a sinusoidal waveform of 40 Hz. The input acoustic signal is a homogeneous sound signal with a constant frequency higher than 40 Hz and constant sound pressure. As a result, the envelope of the amplitude waveform of the output acoustic signal has a shape that follows a sinusoidal wave.

[0042] Specifically, as shown in Figure 7, in the third example, both the rising and falling edges of the envelope A of the amplitude waveform of the output acoustic signal are smooth. In other words, envelope A is sinusoidal.

[0043] In the first to third examples above, the modulation function was assumed to have a periodicity of 40 Hz, but the frequency of the modulation function is not limited to this, and may be, for example, between 35 Hz and 45 Hz. Also, in the first to third examples above, the absolute value of the amplitude of envelope A was assumed to be periodically zero, but this is not limited to this, and a modulation function may be used such that the minimum absolute value of the amplitude of envelope A is greater than zero (for example, half or a quarter of the maximum absolute value).

[0044] In the examples shown in Figures 5 to 7, the sound pressure and frequency of the input acoustic signal are assumed to be constant, but the sound pressure and frequency of the input acoustic signal may change. For example, the input acoustic signal may be a signal representing music, speech, ambient sound, electronic sound, or noise. In this case, although the envelope of the amplitude waveform of the output acoustic signal will have a shape that is strictly different from the waveform representing the modulation function, the general shape of the envelope will be similar to that of the waveform representing the modulation function (e.g., inverse sawtooth wave, sawtooth wave, or sine wave), and it will be possible to provide the listener with the same auditory stimulation as when the sound pressure and frequency of the input acoustic signal are constant.

[0045] (2-4) Fourth example of an output acoustic signal A fourth example of the output acoustic signal will be described. Figure 8 shows the waveform of the fourth example of the output acoustic signal, which is generated by adding an auxiliary acoustic signal to the input acoustic signal.

[0046] In the fourth example, the auxiliary acoustic signal contains pulses with a period of 1 / 40 second. The input acoustic signal has a constant frequency higher than 40 Hz and is an acoustic signal with a smoothly changing sound pressure. As a result, as shown in Figure 8, the output acoustic signal has pulses with a period of 1 / 40 second, and the portion other than the pulses has a waveform similar to that of the input acoustic signal.

[0047] (2-5) Fifth example of an output acoustic signal A fifth example of the output acoustic signal will be described. Figure 9 shows the waveform of the fifth example of the output acoustic signal, which is generated independently without using the input acoustic signal. In the fifth example, the output acoustic signal is a signal with pulses having a period of 1 / 40 second.

[0048] In the fourth and fifth examples above, the pulse was assumed to have a period of 1 / 40 second (i.e., a period corresponding to 40 Hz), but the pulse period is not limited to this, and may, for example, correspond to a frequency between 35 Hz and 45 Hz. Also, in the auxiliary acoustic signal of the fourth example and the output acoustic signal of the fifth example above, the pulse width and sound pressure were assumed to be constant, but this is not limited to this, and at least one of the pulse width and sound pressure may change.

[0049] (3) Examples (3-1) Example 1 Examples of the technology of this disclosure will be described. In the experiment according to Example 1, 38 subjects were randomly assigned to an intervention group (19 subjects, 63.2 ± 5.0 years old) and a SHAM group (19 subjects, 63.3 ± 4.8 years old). A pulsed sound with a period of 40 Hz (a sound containing a 1 ms square wave every 25 ms) was prepared as the intervention sound, and a random pulsed sound (a sound containing a 1 ms square wave at random intervals (uniform distribution with an average interval of 25 ms)) was prepared as the SHAM sound. These stimulus sounds were presented through headphones for 45 minutes. The volume of the stimulus sounds was set to an equivalent noise level of 60 dB + hearing level for 27 subjects, and to 60 dB for 11 subjects. Figure 10 shows the waveforms of the stimulus sounds used in the experiment of Example 1. Figure 10(a) shows the waveform of the pulsed sound with periodic fluctuations of 40 Hz used as the intervention sound, and Figure 10(b) shows the waveform of the random pulsed sound used as the SHAM sound.

[0050] Before and after the presentation of the audio source described above, a Category Fluency Test (CFT) was performed. The CFT is a task that requires the efficient use of semantic memory to search for semantic categories that match the instruction from previously accumulated vocabulary and formed concepts, and to generate words belonging to those categories. The CFT can be used to evaluate the cognitive functions of the subject related to language, memory, and executive function (particularly cognitive functions influenced by the activation of the frontal lobe, hippocampus, and precuneus). The CFT is a type of Word Fluency Test (WFT), and the WFT is one of the tasks performed in the Frontal Assessment Battery (FAB).

[0051] The specific details of the CFT conducted in the experiment of Example 1 are as follows: In the measurement before the presentation of the sound source, the subject was asked to name as many words belonging to the "vegetable" category as possible in 60 seconds, and the number of words that were named was counted. In the measurement after the presentation of the sound source, the subject was asked to name as many words belonging to the "animal" category as possible in 60 seconds, and the number of words named was counted. Then, a score was evaluated based on the number of words counted in the measurements before and after the presentation of the sound source. The results are shown in Figure 11. Figure 11 is a diagram showing the results of the experiment of Example 1.

[0052] As shown in Figure 11, the score significantly improved only in the intervention group that listened to a pulse sound with a period of 40 Hz. Specifically, the change in score before and after sound source presentation was +4.7 ± 3.4 points (p = 0.000) in the intervention group and +0.4 ± 5.5 points (p = 0.780) in the SHAM group, with a difference of p = 0.007 between the groups.

[0053] (3-2) Example 2 In the experiment related to Example 2, 39 subjects were randomly assigned to an intervention group (19 subjects, 62.5 ± 5.5 years old) and a SHAM group (20 subjects, 63.3 ± 6.1 years old). A modulated sound was prepared as the intervention sound by applying 40 Hz amplitude modulation to the acoustic signal of music content, and a modulated sound was prepared as the SHAM sound by applying 80 Hz amplitude modulation to the acoustic signal of music content. These stimulus sounds were presented through a speaker for 60 minutes. The volume of the stimulus sounds was set to 54 dBA as the baseline, and corrected for the three-step hearing level (maximum 74 dBA).

[0054] Before and after the presentation of the audio source described above, the Category Fluency Test (CFT) and the Idea Fluency Test (IFT) were measured. For the IFT, we used the application test included in the TCT (Test for Creative Thinking) creativity assessment. The IFT can be used to assess the cognitive functions of the subjects related to language, memory, and executive function (particularly cognitive functions influenced by the activation of the frontal lobe, hippocampus, and precuneus).

[0055] The specific details of the CFT performed in the experiment of Example 2 were the same as those of the CFT performed in the experiment of Example 1 described above, and the standardized score was evaluated based on the number of words counted in measurements before and after the presentation of the sound source. The results are shown in Figure 12. Figure 12 shows the results of the categorical fluency task in Example 2.

[0056] As shown in Figure 12, an improvement in scores was observed only in the intervention group that listened to modulated sounds generated by 40 Hz amplitude modulation. Specifically, the change in scores before and after sound source presentation was +2.58 ± 4.23 points in the intervention group and +0.40 ± 4.44 points in the SHAM group, with a difference of p = 0.068 between the groups.

[0057] The specific details of the IFT conducted in the experiment of Example 2 are as follows: In the measurement before the presentation of the sound source, the subject was asked to list as many uses of a "wooden cutting board" as possible in 120 seconds, and the number of uses that could be listed was counted. In the measurement after the presentation of the sound source, the subject was asked to list as many uses of an "empty canned food can" as possible in 120 seconds, and the number of uses that could be listed was counted. The number of uses counted in the measurements before and after the presentation of the sound source was then evaluated. The results are shown in Figure 13. Figure 13 shows the results of the idea fluency task in Example 2.

[0058] As shown in Figure 13, the score improved only in the intervention group, which listened to a modulated sound generated by amplitude modulation at 40 Hz. Specifically, the change in score before and after sound source presentation was +2.14 ± 2.71 points in the intervention group and -0.12 ± 2.65 points in the SHAM group, with a difference of p = 0.007 between the groups.

[0059] (3-3) Example 3 In the experiment related to Example 3, 37 healthy subjects (37.7 ± 8.7 years old) were involved, and three types of sound sources were prepared. The first sound source was unmodulated white noise (WN). The second sound source was a modulated sound (GWS) generated by applying 40Hz amplitude modulation to the white noise. The third sound source was a binaural beat (BB) consisting of a 440Hz sine wave presented to the right ear and a 400Hz sine wave presented to the left ear. All subjects were presented with each of these three sound sources through headphones at an equivalent noise level of 74dB. These three sound sources were presented in a counterbalanced order.

[0060] For each of the three types of sound sources mentioned above, the Sustained Attention to Response Task (SART) was measured during the presentation of the sound source. SART can be used to evaluate the attentional function of the subjects. Generally, attentional function is classified into four types: sustained attention, selective attention, divided attention, and shifting attention. SART is a type of Continuous Performance Test (CPT) used to evaluate sustained attention (the ability to maintain attention to one thing, a cognitive function particularly influenced by the frontal lobe or the frontal-parietal lobe network).

[0061] The specific details of the SART conducted in the experiment of Example 3 are as follows: Numbers from 1 to 9 were displayed in a random order on a screen placed in front of the subject. The subject was instructed not to press the button when a specific number (the number 3) was displayed, and to press the button as quickly as possible when any other number was displayed. The number of times the subject pressed the button (judged as "No go mistakes") out of 25 trials in which the specific number was displayed, and the number of times the subject did not press the button (judged as "Go mistakes") out of 200 trials in which any other number was displayed were counted and evaluated. The results are shown in Figures 14 and 15. Figure 14 shows the results of evaluating the number of "Go mistakes" in the sustained attention task of Example 3. Figure 15 shows the results of evaluating the number of "No go mistakes" in the sustained attention task of Example 3.

[0062] As shown in Figure 14, when comparing the average number of "Go mistakes," the number of mistakes was lower when binaural beats (BB) were presented compared to when white noise (WN) was presented, and even lower when modulated sound (GWS) was presented. Furthermore, as shown in Figure 15, when comparing the average number of "No go mistakes," the number of mistakes was lower when modulated sound (GWS) was presented compared to when white noise (WN) or binaural beats (BB) were presented.

[0063] (3-4) Summary of Examples In Example 1, it was shown that presenting subjects with auditory stimuli based on a signal with a pulse period corresponding to 40 Hz improved their performance on the Category Fluency Test (CFT). In Example 2, it was shown that presenting subjects with auditory stimuli based on a signal generated by applying 40 Hz amplitude modulation to an input acoustic signal improved their performance on both the Category Fluency Test (CFT) and the Idea Fluency Test (IFT). These results indicate that presenting subjects with auditory stimuli based on acoustic signals with periodic fluctuations corresponding to 40 Hz improves their fluency. Furthermore, since CFT and IFT can evaluate the cognitive and executive functions related to language in subjects, it was shown that presenting subjects with auditory stimuli based on acoustic signals with periodic fluctuations corresponding to 40 Hz improves their cognitive and executive functions related to language. Additionally, since the TCT Creativity Test used as the IFT in Example 2 evaluates the creative thinking of subjects, it was shown that presenting subjects with auditory stimuli based on acoustic signals with periodic fluctuations corresponding to 40 Hz improves their cognitive functions related to creativity. In Example 3, it was shown that presenting a subject with an auditory stimulus based on a signal generated by applying 40Hz amplitude modulation to white noise improved the results of the sustained attention task (SART). This result indicates that presenting a subject with an auditory stimulus based on an acoustic signal having periodic fluctuations corresponding to 40Hz improves the subject's attentional function. Therefore, in this embodiment, by having the user US1 listen to the sound emitted from the acoustic output device 30, at least one of the following can be expected: improvement in the user US1's attentional function, improvement in fluency, improvement in executive function, improvement in creativity, and improvement in cognitive function.

[0064] (4) Acoustic signal processing The acoustic signal processing of this embodiment will now be described. Figure 16 is a diagram showing the overall flow of acoustic signal processing by the signal processing device 10 of this embodiment. The processing in Figure 16 is realized by the processor 12 of the signal processing device 10 reading and executing a program stored in the storage device 11. Note that at least a part of the processing in Figure 16 may be realized by one or more dedicated circuits.

[0065] The acoustic signal processing shown in Figure 16 starts when any of the following start conditions are met. The acoustic signal processing shown in Figure 16 was invoked by another process or an external instruction. The user performed an operation to invoke the acoustic signal processing shown in Figure 16. The signal processing device 10 has reached a predetermined state (for example, power-on). The designated date and time have arrived. A predetermined amount of time has elapsed since a predetermined event (for example, the activation of the signal processing device 10, or the previous execution of the acoustic signal processing shown in Figure 16).

[0066] As shown in Figure 16, the signal processing device 10 performs the selection of an auditory stimulus (S110). Specifically, the signal processing device 10 selects from a plurality of pre-stored types of output acoustic signals to be generated in order to present an auditory stimulus to the subject. As an example, the signal processing device 10 selects which of the five types of output acoustic signals described using Figures 5 to 9 to generate. The selection of which type of output acoustic signal to generate may be determined based on input operations by the user or another party or external instructions, or it may be determined by an algorithm.

[0067] In this embodiment, "other person" refers to, for example, at least one of the following: • The user's family, friends, or acquaintances • Medical professionals (e.g., the user's doctor) • Creator or provider of content corresponding to the input audio signal • Provider of signal processing device 10 • Administrator of the facility used by the user

[0068] Furthermore, when the signal processing device 10 selects an acoustic signal obtained by amplitude modulating the input acoustic signal (for example, the acoustic signals shown in Figures 5 to 7) as the output acoustic signal, it determines the modulation method. The modulation method determined here includes, for example, at least one of the modulation function used for modulation processing and the modulation degree corresponding to the degree of change in amplitude due to modulation. The selection of which modulation function to use may be determined based on input operations by the user or another party or external instructions, or it may be determined by an algorithm.

[0069] After step S110, the signal processing device 10 performs the acquisition of the input acoustic signal (S111). Specifically, the signal processing device 10 receives the input acoustic signal sent from the sound source device 50. In step S111, the signal processing device 10 may further perform A / D conversion of the input acoustic signal. Note that if an acoustic signal generated without using the input acoustic signal (for example, the acoustic signal shown in Figure 9) is selected as the output acoustic signal in step S110, the signal processing device 10 may omit the processing in S111.

[0070] The input acoustic signal corresponds to at least one of the following, for example: • Musical content (e.g., singing, playing instruments, or a combination thereof (i.e., songs). This may include audio content accompanying video content.) • Audio content (e.g., readings, narrations, announcements, radio dramas, monologues, conversations, monologues, or combinations thereof; may include audio content accompanying video content). • Other audio content (e.g., electronic sounds, ambient sounds, or machine sounds) However, singing or audio content is not limited to sounds produced by human vocal organs, but may include sounds generated by speech synthesis technology.

[0071] After step S111, the signal processing device 10 performs the generation of an output acoustic signal (S112). For example, if an acoustic signal obtained by amplitude modulating the input acoustic signal (for example, the acoustic signals shown in Figures 5 to 7) is selected as the output acoustic signal in S110, the signal processing device 10 performs modulation processing on the input acoustic signal acquired in S111. As an example, the signal processing device 10 performs amplitude modulation on the input acoustic signal using a modulation function with a frequency corresponding to a gamma wave (for example, a frequency between 35 Hz and 45 Hz). As a result, the input acoustic signal is given an amplitude change (periodic fluctuation of volume) corresponding to the above frequency.

[0072] For example, if in S110 an acoustic signal obtained by adding an auxiliary acoustic signal to the input acoustic signal (for example, the acoustic signal shown in Figure 8) is selected as the output acoustic signal, the signal processing device 10 generates an auxiliary acoustic signal and performs the process of adding the auxiliary acoustic signal to the input acoustic signal acquired in S111. As an example, the signal processing device 10 adds an auxiliary acoustic signal to the input acoustic signal that has pulses with a period corresponding to the frequency of gamma waves (for example, a frequency between 35 Hz and 45 Hz). As a result, the acoustic signal after addition also has periodic fluctuations corresponding to the frequency of gamma waves.

[0073] Furthermore, for example, if an independently generated acoustic signal (for example, the acoustic signal shown in Figure 9) is selected as the output acoustic signal in S110, the signal processing device 10 generates the output acoustic signal without using the input acoustic signal. As an example, the signal processing device 10 generates an output acoustic signal having a pulse with a period corresponding to the frequency of a gamma wave (for example, a frequency between 35 Hz and 45 Hz).

[0074] In step S112, the signal processing device 10 may further perform at least one of the following: amplification of the output acoustic signal, volume adjustment, or D / A conversion.

[0075] After step S112, the signal processing device 10 performs the output acoustic signal transmission (S113). Specifically, the signal processing device 10 transmits the output acoustic signal generated in step S112 to the acoustic output device 30. The acoustic output device 30 presents an acoustic stimulus to the listener by generating a sound corresponding to the output acoustic signal.

[0076] The signal processing device 10 terminates the acoustic signal processing shown in Figure 16 in step S113. The processing shown in Figure 16 may also be terminated according to specific termination conditions (for example, when a certain amount of time has elapsed, when a user operation has been performed, or when the output history of the sound stimulus has reached a predetermined state). Note that the order of processing by the signal processing device 10 is not limited to the example shown in Figure 16; for example, the acquisition of the input acoustic signal (S111) may be performed before the selection of the sound stimulus (S110).

[0077] (5) Summary As described above, the signal processing device 10 of this embodiment generates an output acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves. The signal processing device 10 then presents an acoustic stimulus based on the generated output acoustic signal to the subject via the acoustic output device 30, thereby improving the subject's brain function.

[0078] Brain functions that improve with the presentation of auditory stimuli include at least one of the following: • Attention function ·Fluency • Executive function ·Creativity • Cognitive functions related to language • Cognitive functions affected by activation of the frontal lobe, hippocampus, and precuneus • Cognitive functions that can be evaluated by frontal lobe function tests • Attentional function that can be evaluated through sustained attention tasks • Cognitive functions that can be assessed using categorical fluency tasks • Cognitive functions that can be assessed through idea fluency tasks • Memory retrieval function • Function to recall memories

[0079] The gamma wave frequency corresponding to the periodic fluctuations of the output acoustic signal may be between 35 Hz and 45 Hz. This allows for a greater improvement effect when the auditory stimulus based on the output acoustic signal is presented to the subject.

[0080] The output acoustic signal may also be a signal having pulses with a period corresponding to the frequency of gamma waves. This allows for a greater expected improvement effect when the auditory stimulus based on the output acoustic signal is presented to the subject.

[0081] The output acoustic signal may be generated by applying amplitude modulation to the input acoustic signal according to the gamma wave frequency. This allows the subject to receive auditory stimulation while listening to the content (e.g., music or speech) contained in the input acoustic signal.

[0082] (6) Variant The storage device 11 may be connected to the signal processing device 10 via a network NW. The display 21 may be built into the signal processing device 10.

[0083] The above description shows an example in which the signal processing device 10 modulates the entire input acoustic signal. However, the signal processing device 10 may also extract a portion of the acoustic signal (for example, background sound that does not include human voices), modulate only the extracted acoustic signal, and then generate the output acoustic signal.

[0084] The above description shows an example in which the signal processing device 10 modulates the input acoustic signal to generate an output acoustic signal, which is then sent to the acoustic output device 30. However, the signal processing device 10 may also generate an output acoustic signal by combining the modulated input acoustic signal obtained by modulating the input acoustic signal with other acoustic signals, and then send the generated output acoustic signal to the acoustic output device 30. Alternatively, the signal processing device 10 may send the modulated input acoustic signal and the other acoustic signals to the acoustic output device 30 simultaneously without combining them.

[0085] In the above description, an example was shown in which the output acoustic signal generated by the signal processing device 10 modulating the input acoustic signal has an inverse sawtooth or sawtooth envelope of amplitude waveform, and the rising and falling edges of the envelope are asymmetrical. However, the output acoustic signal generated by the signal processing device 10 is not limited to these examples, and may have other amplitude waveforms in which the rising and falling edges of the envelope of amplitude waveform are asymmetrical.

[0086] For example, in the rising portion of the envelope, the slope of the tangent to the envelope may gradually decrease, or the slope of the tangent to the envelope may gradually increase. Also, for example, in the falling portion of the envelope, the slope of the tangent to the envelope may gradually decrease, or the slope of the tangent to the envelope may gradually increase.

[0087] The above explanation mainly described an example where the frequency corresponding to the periodic fluctuations of the output acoustic signal is between 35 Hz and 45 Hz. However, the output acoustic signal generated by the signal processing device 10 is not limited to this, and only has to have periodic fluctuations that affect the induction of gamma waves in the listener's brain. For example, the periodic fluctuations may correspond to frequencies between 25 Hz and 140 Hz. Also, for example, the frequency corresponding to the periodic fluctuations may change over time, and may partially have frequencies below 35 Hz or higher than 45 Hz.

[0088] The above description describes a case where the output acoustic signal generated by the signal processing device 10 is output to an acoustic output device 30 that emits a sound corresponding to the output acoustic signal for the user to hear. However, the destination of the output acoustic signal from the signal processing device 10 is not limited to this. For example, the signal processing device 10 may output the output acoustic signal to an external storage device or information processing device via a communication network or broadcast.

[0089] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the embodiments described above. Furthermore, the embodiments described above can be improved or modified in various ways without departing from the spirit of the present invention. In addition, the embodiments and modifications described above can be combined. [Explanation of symbols]

[0090] 1: Sound System 10: Signal Processing Device 11:Storage device 12: Processor 13: Input / Output Interface 14: Communication Interface 21: Display 30: Audio output device 50: Sound source device

Claims

1. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the attention function of a subject by presenting them with an auditory stimulus based on the aforementioned acoustic signal. Attention function improvement system.

2. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the attentional function of a subject, which can be evaluated by a sustained attention task, by presenting the subject with an auditory stimulus based on the aforementioned acoustic signal. Attention function improvement system.

3. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the fluency of a subject by presenting them with auditory stimuli based on the aforementioned acoustic signals. Fluency improvement system.

4. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the subject's fluency, which can be evaluated by a categorical fluency task, by presenting the subject with auditory stimuli based on the aforementioned acoustic signals. Fluency improvement system.

5. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the subject's fluency, which can be evaluated by an idea fluency task, by presenting the subject with auditory stimuli based on the aforementioned acoustic signals. Fluency improvement system.

6. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the language-related cognitive functions of a subject by presenting them with auditory stimuli based on the aforementioned acoustic signals. Cognitive function improvement system.

7. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving cognitive functions affected by activation of the frontal lobe, hippocampus, and precuneus of a subject by presenting the subject with auditory stimuli based on the aforementioned acoustic signals. Cognitive function improvement system.

8. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the cognitive function of a subject, which can be evaluated by frontal lobe function tests, by presenting the subject with auditory stimuli based on the aforementioned acoustic signals. Cognitive function improvement system.

9. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the executive function of a subject by presenting the subject with auditory stimuli based on the aforementioned acoustic signals. Executive function improvement system.

10. A means for generating an acoustic signal having periodic fluctuations corresponding to the frequency of gamma waves, The system includes means for improving the creativity of a subject by presenting them with auditory stimuli based on the aforementioned acoustic signals. A system for improving creativity.

11. The frequency of the gamma wave is between 35 Hz and 45 Hz. The improvement system according to any one of claims 1 to 10.

12. The aforementioned acoustic signal is a signal having pulses with a period corresponding to the frequency of the gamma wave. The improvement system according to any one of claims 1 to 10.

13. The aforementioned acoustic signal is generated by applying amplitude modulation to the input acoustic signal according to the frequency of the gamma wave. The improvement system according to any one of claims 1 to 10.

14. A program for causing a computer to function as one of the means of the improvement system described in any one of claims 1 to 10.

Images