WO2014083375A1

WO2014083375A1 - Entrainment device

Info

Publication number: WO2014083375A1
Application number: PCT/IB2012/002963
Authority: WO
Inventors: Jun Imamura; Sim Yong HWEE; Chong Kok SENG
Original assignee: Panasonic Corporaton
Priority date: 2012-11-30
Filing date: 2012-11-30
Publication date: 2014-06-05

Abstract

An entrainment device includes a sensor configured to capture sensor data related to the effect of entrainment, an entrainment effect analyser configured to process the sensor data to produce feedback data, an entrainment programmer configured to convert the feedback data into entrainment parameters or program, an entrainment embedding block configured to embed entrainment waveforms into a signal to generate entrained signal according to the entrainment parameters or program.

Description

ΕΝΊΕ ]ΙΜΕΤ DEVICE

Technical Field

[0001] The present disclosure relates to entrainment with arbitrary music to force the brain into a desired brain state. It can be used in conjunction with any audio playback device.

Background Art

[0002] When our brain performs various activities, it produces electrical pulses measurable with an electroencephalography

(EEG) machine. The electrical pulses are generated by the collective activities of the brain neurons, and exhibit a periodic characteristic. The periodicity of the electric pulses depends on the state of the brain, as shown in Table 1. In general, the more alert our brain is, the higher the periodicity.

Table 1: Brain wave frequency at different brain state

[0003] Specifically for sleep, its onset is induced by sleep-promoting neurons, located in the ventrolateral preoptic nucleus

(VLPO) . It is thought that these sleep-promoting neurons project two inhibitory neurotransmitters, GABA type A and galanin, to arousal- promoting neurons. Activation of sleep-promoting neurons hence inhibits arousal-promoting neurons, which leads to sleep [6] . During activation of sleep-promoting neurons, electrical pulses with a certain periodic characteristic can be observed. On the other hand, when those sleep-promoting neurons are not activated i.e. when one is awake, electrical pulses with a lower periodicity can be observed [7] .

[0004] Brainwave entrainment is the process of synchronising the brainwave frequencies to an external, rhythmic stimulus to maintain a desired brain state. When presented with an external, rhythmic stimulus such as an audible tone, the brain converts the aural information into electrical impulses. After prolonged exposure to the stimulus, the brain would synchronize its internal rhythm to that of the electrical impulses, thereby achieving the objective of brainwave entrainment. This is also known as ^ΛFrequency Following Response' .

[0005] The theory of brainwave entrainment has been studied clinically and proven to be effective in numerous cases as a therapeutic tool. Various types of mental issues, such as cognitive deficits, stress pain, headache, migraines, etc were found to benefit from brainwave entrainment [1] .

[0006] In the prior arts, there exist several types of entrainment methods:

1. Binaural beat: Play a tone of frequency fl to one ear and a tone of frequency f2 to another ear to stimulate an (f2-fl) beat in the brain.

2. Monaural beat: Play a sum of two tones of frequencies fl and f2 to stimulate an (f2-fl) beat in the brain.

3. Isochronic tone: Create a beat by turning on and off a tone at frequency f to stimulate an f beat in the brain.

[0007] Figure 6 shows the typical waveforms of binaural beat, monaural beat and isochronic tone.

[0008] The problems with the current entrainment devices:

1. Lack of custcmisability and flexibility

The songs are pre-selected and pre-entrained. The users cannot use their preferred songs. The level of entrainment is predetermined. The users cannot select a different level/degree of entrainment, if the entrainment is deemed ineffective.

[0009]

2. Lack of assessment, feedback and improvement

There is no assessment on the effect of entrainment on the user' s wellness. The user is unaware of whether entrainment has indeed improved their wellness or not. If the entrainment program based on the user's setting fails to produce result, the entrainment program isn't automatically adjusted for the user according to some assessment result.

Summary of Invention

[0010] It is the object of the present disclosure to introduce a music entrainment device with user customisability, feedback and automatic adjustment.

[0011] The entrainment device of the present disclosure solves the above problems by introducing:

1. Customisability and flexibility

The user can connect their music player to the device of the present disclosure and turn their favourite songs into entrained music. It's believed that the user's emotional and sentimental connection with their favourite songs can sublimely heighten the effect of entrainment.

[0012] The entrainment type is determined by the user through a user interface, and the corresponding entrainment signal is embedded into user' songs of choice. The volume and degree of entrainment can also be set through the user interface.

[0013]

2. Assessment, feedback and automatic adjustment The device of the present disclosure provides a sensor to assess the effect of entrainment. The effect of entrainment derived from the sensor data is presented to the user for feedback purpose. The effect of entrainment is also used to adjust the entrainment program set by the user to improve the effect.

[0014] A use case that can benefit considerably from this inventive device is sleep entrainment.

[0015] Broadly speaking, there are two types of sleep stages in a typical sleep cycle: rapid eye movement (REM) and non- rapid eye movement (NREM or non-REM) , and each type has unique physiological, neurological, and psychological features. The NREM sleep stage can be further divided into three stages: Nl, N2, N3 and N4. 3, and N4 are also known as delta sleep or slow-wave sleep (SWS)

[2] . A typical sleep occurs in cycles of REM and NREM, as shown in Figure 5 (a) . The most important sleep stages are the SWS and REM. It has been shown that procedural memory benefits from REM sleep whereas declarative memory benefits from SWS sleep [3] . It has also been shown that men with a higher percentage of SWS to the total amount of sleep had higher growth hormone secretion [4] . Therefore, the occurrence and durations of the SWS and REM sleep are correlated with sleep quality.

[0016] In a separate study, it's found that sleep stages can be estimated through heartbeat rate, respiratory rate and other body movement [5] . Therefore, by capturing the unique signals of heartbeat rate, respiratory rate and other body movement with a sensor, such as radar, it's possible to measure the amount of SWS and REM episodes, and thereby gauge the effect of entrainment, i.e. the sleep quality.

[0017] With this useful feedback information from the sensor, the degree of entrainment can be increased if the effect of entrainment is found to be lacking. To help relax the user into the sleep mode, the entrainment type can be changed from alpha (relaxation wave) to delta (deep sleep wave) or changed to sleep-inducing (wave that corresponds to periodicity of electrical pulses observed when sleep-promoting neurons are activated) . The change can be timed according to the typical sleep onset time of the user, which can be estimated as the time at which the user's body movement drops below a certain threshold.

[0018] In one aspect, an entrainment device is provided, that includes a sensor configured to capture sensor data related to the effect of entrainment, an entrainment effect analyser configured to process the sensor data to produce feedback data, an entrainment programmer configured to convert the feedback data into entrainment parameters or program, and an entrainment entedding block configured to embed entrainment waveforms into a signal to generate entrained signal according to the entrainment parameters or program.

Brief Description of Drawings

[0019]

Fig. 1 shows a configuration of an entrainment device of the first embodiment;

Fig. 2 shows a configuration of an entrainment device of the second embodiment;

Fig. 3 shows a possible physical implementation of the second embodiment;

Fig. 4 shows a configuration of an entrainment device of the third embodiment with detailed entrainment embedding;

Fig. 5 shows the fourth embodiment with detailed entrainment programmer-1;

Fig. 6 shows the fourth embodiment with detailed entrainment programmer-2; and Fig. 7 shows various entrainment waveforms used in the prior arts.

Description of Embodiments

[0020] The following embodiment is merely illustrative for the principles of various inventive steps. It's understood that variations of the details described herein will be apparent to others skilled in the art.

[0021]

First Embodiment

As the first embodiment, an entrainment device includes an Entrainment Embedding block, a Sensor, an Entrainment Effect Analyser and an Entrainment Programmer.

[0022] The entrainment device (100) is shown in Figure 1.

[0023] The Entrainment Embeckiing block (101) processes a signal according entrainment parameters to produce an entrained signal. The entrainment parameters can be constant, or time varying in the form of an entrainment program. The entrainment parameters include, but not limited to: entrainment type, entrainment degree, volume and duration. An entrainment waveform corresponding to the entrainment type is modulated into the music. The entrainment degree determines the amount of entrainment to be embedded into the music; the entrainment volume decides the overall loudness of the entrained rriusic; the duration specifies when the entrainment starts and ends.

[0024] The Sensor (102) senses the user's response to the entrained signal to verify the effectiveness of entrainment. For example, in the case of sleep entrainment, it tracks the user's motion during sleep which is derived from user's respiratory, turning over, and heart-beat. It can be a radar transceiver that transmits radio wave to the user, and the recorded reflected wave represents the motion data. In another embodiment, it can be a detachable pressure sensor that the user can put on the bed, and the sensor reading represents the motion data. Other alternative means of detecting motion, such as ultrasound sensor and camera, are also within the scope of this invention.

[0025] The Entrainment Effect Analyser (103) converts the sensor data into feedback data. From the sensor data, it extracts the parameters related to the psychological or physiological well-being of the user to derive the feedback data. For example, in the case of sleep entrainment, the respiratory motion data is converted to the sleep stages of the user.

[0026] The Entrainment Programmer (104) derives an improved set of entrainment parameters, or an improved entrainment program, based on the feedback data. For example, in the case of sleep entrainment, a lack of SWS and REM in the user's sleep stages implies poor sleep quality. The Entrainment Programmer (104) would increase the degree of entrainment, and lengthen the duration of entrainment in future sleep sessions.

[0027]

Second Embodiment

As the second embodiment, the entrainment device includes an Entrainment Firibedding block, a Sensor, an Entrainment Effect Analyser, an Entrainment Programmer, a User Interface, a Port/Socket for an external music device, a Playback device and a Display.

[0028] The entrainment device (200) is shown in Figure 2.

Block (201) to (204) are the same as block (101) to (104) of the first embodiment respectively.

[0029] The User Interface (205) receives user inputs and generates initial entrainment parameters for the Entrainment Embedding (201) block. The interface can be buttons or a touch screen. The user inputs include the volurre, the type and the degree of entrainment. The type of entrainment can be sleep' , 'relax' , 'alert' . The degree of entrainment can be 'high' , 'medium'^' or 'low' . It can optionally consist of sliders or knobs to provide the user with fine-grained control.

[0030] The Plug/Socket (206) lets the user connect their music player to the device. It then transmits the music signal from the music player to the Entrainment Embedding (201) block. For example, it can be a connector for Apple iPhone or iPod, a mini USB interface for android phones, or a phone jack for analogue music signal.

[0031] The Playback (207) device renders the entrained music generated by the Entrainment Errtoedding (201) block. It can be a mono speaker, stereo speakers, speaker array, headphone or audio beam speaker. The speakers can be built into the device, or detachable, to allow the user to place them at any preferred listening locations.

[0032] The Display (208) presents the feedback data from the Entrainment Effect Analyser (203) block visually to the user. It can be an LCD screen. For example, it can display sleep stages over the course of the sleep with a graph. In addition, it can summarize the overall sleep quality with a sleep score (e.g. 1 - very bad sleep, 10 - perfect sleep) . The sleep quality can be computed as a function of the frequency of S S and REM occurrences. The format of visual presentation doesn't limit the scope of this invention.

[0033] Figure 3 shows the physical implementation of this embodiment. It's understood that the form factor illustrated here is only exemplary. It might differ from the actual product embodying this invention.

[0034]

Third Embodiment

As the third embodiment, the Entrainment Embedding block (101/201) of the first and second embodiment further includes a Signal Splitter, an Entrainment Signal Database, an Embedding block, two Gain blocks and a Summation block. These processing blocks are shown in Figure 4.

[0035] The Signal Splitter (401) block splits the input music x into two signals, x_x and x₂. For example, by using lowpass and highpass filters for splitting, x_x is the lowpass signal of x, and x₂ is the highpass signal of x. The split signals should also be delay- aligned.

[0036] The Entrainment Signal Database (402) contains entrainment waveforms associated with different entrainment types requested by the user or the Entrainment Programmer (104/204) . In one example, isochronic beats are adopted, and the waveforms with beat frequencies associated with different states of consciousness are stored in this database. This is shown in Table 2. The entrainment waveforms can be pre-generated or synthesized dynamically. Dynamic synthesis is suitable for smoothly switching entrainment type in fine frequency steps over a time interval.

Table 2 : Entrainment waveform for different type of entrainment

[0037] The Embedding block (403) embeds the selected entrainment waveform e into the lowpass signal Xi to generate an embedded signal x₃. For example, the embedding process can be amplitude modulation:

[0038] The Gain blocks (404, 405) scale the highpass signal x₂ and embedded signal x₃ by g₂ and g₃ respectively to produce scaled signals y₂ and y₃:

y₃ = g₃-¾

[0039] Ihe values of g₂ and g₃ are decided by the music volume v and the degree of entrainment Θ chosen by the user. For example, if Θ has a value between 0 and 1, then

g₂ = v Θ

[0040] The Summation block (406) sums the scaled signals to produce an entrained music:

[0041]

Fourth Embodiment

As the fourth embodiment, the Entrainment Programmer (104/204) of the first and second embodiment derives a sleep program based on objective indexes like sleep onset, sleep duration, the frequency of SWS and REM occurrences, and the time taken to wake up from the first alarm had rung. The program can also be based on user's subjective feelings. For example, the device asks user how he/she felt about previous night sleeping via user interface, and then, the Entrainment Prograrrmer generates sleep program using either or both of objective indexes and subjective feelings. The sleep program comprises the entrainment types, entrainment degrees volume and durations throughout a sleep session. These parameters can be variables of sleep stages when the prograrrmer changes its output dynamically along with the user's sleep stages.

[0042] Figure 5 (a) shows a plot of feedback data (sleep data in this example) generated by the Entrainment Effect Analyser (103/203) block. The sleep onset value marks the transition from awake to NREM. The Sleep duration value is the time from sleep onset to the next awake stage, fr and fs are total intervals of REM sleeping and SWS during the sleep, respectively. This plot can be based on the sleep data from the previous sleep session, or the average of several prior sleep sessions.

[0043] Figure 5(b) shows the entrainment type derived by the Entrainment Programmer (104/204) for future sleep sessions. In this example, the entrainment type starts with alpha to relax the user, and smoothly changes to delta to make the user drowsy over the course of the sleep onset period. In the sleep duration, the entertainment type changes along with current sleep stage of the user. In this example, entrainment type is changed to shorten the transition time from SWS (REM) to REM (SWS) using alpha (delta) wave shortly after the sleep stage changed from SWS (REM) . After that, in the end of the sleep, the entrainment type switches to beta to make the user feel alert.

[0044] Figure 5 (c) shows the entrainment degree Θ derived by the Entrainment Programmer (104/204) for future sleep sessions. For example, it can be based on total REM and SWS episodes, tr and ts

Θ = f (tr,ts)

[0045] A large value should be assigned to Θ if tr and ts are low, vice versa.

[0046] Figure 5 (d) shows volume v derived by the

Entrainment Programmer (104/204) for future sleep sessions. For example, the volume v can gradually decrease toward zero shortly after the sleep onset, but sometimes increase when the device try to use entrained sound to shorten transition time. After that, the volume gradually increase again prior to the user's awakening.

[0047] Sound entrainment parameter can also be generated in different way. Another example is described in the figure from Figure 6(a) to Figure 6(d). Different from Figure5, these entrainment parameters are generated to lengthen the duration of REM and SWS sleeping. In order to this, alpha (delta) wave is entrained when the sleep stage is in REM (SWS) .

[0048] Both methods described in Figure 5 and Figure 6 are effective, but effects will differ in each user, or some users might feel annoying to hear sounds while the user falls asleep the program sets its volume smaller in the case. The Entrainment Programmer can be customized and flexible along with previous data from sensor, and/or user's feeling.

[0049] In the above embodiments, each of the Entrainment

Embedding block, the Entrainment Effect Analyser, and the Entrainment Programmer may be implemented by an electrical circuit, a programmed processor or a processor executing a stored program (such as CPU and MPU) , or combination thereof.

[0050] Although the present disclosure has been described in connection with specified embodiments thereof, many other modifications, corrections and applications are apparent to those skilled in the art. Therefore, the present invention is not limited by the disclosure provided herein but limited only to the scope of the appended claims.

References

[0051]

[1] Tina L. Huang, "Comprehensive review of the psychological effects of brainwave entrainment", Alternative therapies in Health and Medicine, Sep/Oct 2008

[2] Silber, MH; Ancoli-Israel, S; Bonnet, MH Chokroverty, S; Grigg- Damberger, MM; Hirshkowitz, M; Kapen, S; Keenan, SA et al. (March 2007). "The visual scoring of sleep in adults", Journal of Clinical Sleep Medicine 3 (2) : 121-31. PMID 17557422

[3] Bom, J.; Rasch, J.; Gais, S. (2006). "Sleep to remember", Neuroscientist 12: 410.

[4] Van Cauter, E._; Leproult, R. ,- Plat, L. (2000), "Age-related changes in slow-wave sleep and REM sleep and relationship with growth hormone and Cortisol levels in healthy men", Journal of the American Medical Association 284 (7): 861-868. doi:10.100l/jama.284.7.861. FMTJ 10938176

[5] T. Ishikawa, H. Ando, K. Kobayashi, E. Nishida, K. Watanabe, T. Nakamura,

"A Study on Sleep Stage Estimation via Non-invasive Air Mattress Sensor", Sep 2003

[6] Saper, C.B. ; Scarmiell, T.E.; Lu, J. (2005). "Hypothalamic regulation of sleep and circadian rhythms"

[7] Andrillon T, Nir Y, Staba RJ, Ferrarelli F, Cirelli C, Tononi G, Fried I. "Sleep Spindles in Humans: Insights from Intracranial EEG and Unit Recordings", Dec 2011

Claims

1. An entrainment device, comprising:

a sensor configured to capture sensor data related to the effect of entrainment;

an entrainment effect analyser configured to process the sensor data to produce feedback data;

an entrainment programmer configured to convert the feedback data into entrainment parameters or program; and

an entrainment embedding block configured to embed entrainment waveforms into a signal to generate entrained signal according to the entrainment parameters or program.

2. The entrainment device according to 1, further comprising:

a user interface configured to capture user' s entrainment parameters;

a plug/socket configured to connect to a music device; a playback device configured to render the entrained signal; and

a display configured to present the feedback data to the user.

3. The entrainment device according to 1 or 2, wherein the entrainment parameters or program comprise entrainment type, entrainment degree, volume and/or duration.

4. The entrainment device according to 1 or 2, wherein the entrainment enfoedding block further comprising:

a signal splitter configured to split an input signal into a lowpass signal and a highpass signal;

an entrainment signal database configured to provide an entrainment waveform according to the entrainment type;

an embedding block configured to combine the entrainment waveform with the lowpass signal to produce an embedded signal,·

gain blocks configured to scale the embedded signal and the highpass signal according to the entrainment degree and volume to produce gain-adjusted signals; and

a summation block configured to summ the gain-adjusted signals to produce an entrained signal.

5. The entrainment device according to 1 or 2, wherein the entrainment programmer computes the entrainment program comprising entrainment type, degree, volume and/or duration, according to the feedback data comprising sleep onset, sleep duration and the rapid eye movement (REM) and Slow-wave Sleep (SWS) episodes of the prior sleep sessions.

6. The entrainment device according to 5, wherein the entrainment programmer:

changes the entrainment type from alpha to delta over the sleep onset interval, and to beta when the user awakes;

determines the entrainment degree according to the total REM and SWS intervals; and

decreases the volume over the sleep onset interval, and increases the volume again when the user awakes.