The 2014 Biomedical Engineering International Conference (BMEiCON-2014)

The relationship between EEG and binaural beat

stimulation in meditation

T. Yamsa-ard

Department of Biomedical Engineering Mahidol University, 25/25 Putttamonthon 4, Salaya

Nakornpathom 73170, Thailand email: traisak.y@gmail.com

Abstract-The difficulty to understand meditation is the lack of exact methodology, replication of mind condition and depends on individual meditative practice. From these reasons, this research focuses on a relationship between meditation and EEG. The Quantitative EEG will be analyzed and observed in absolute power of each EEG rhythm. Coherence was also analyzed after participants practice meditation during binaural beat stimulation in both eyes-closed and opened four beat frequencies were selected, 5 Hz, 8Hz, 12Hz, and 18Hz respectively. The binaural beat stimulation will be classified into two groups which are pure beat and meta-music that combined binaural beat with other music. The result demonstrates that coherence is the significant index that shown the relationship between EEG and meditation. Theta and lower alpha absolute power also show the significant relationship which increase at frontal-midline. This research demonstrates that, coherence and absolute power are indices

which can explain a meditation practice during binaural beat stimulation.

Keywords-Meditation, Electroencephalogram, EEG, binaural beat, meta-music

I. INTRODUCTION

Nowadays, business world is very highly competItIve because the information and technology are rapidly changing every day. This cans make-people under stress from working. Moreover, there is also high academic competitive in Thailand. Students usually have exam stress. Merchants are also get stress from economic regression effect. Any people suffer from stress and accumulate it every day. Finally, a high level of stress can lead to disastrous problem.

Stress is not the only thing that leads to disaster. Depression is also the factor that can lead to invaluable loss. According to Thailand national statistics Departlnent of mental health,

Ministry of public health, Thailand sucide rate was 3,873 in 2011. Almost three thousands are men, equating to 9.45 per 100,000 men and 2.72 per 100,000 women. The most significant factor that leads to suicide is depression.

However, there are many activities to reduce stress or negative emotion. Meditation can be one of the solutions for this problem. [1] Meditation is a self-regulate body and mind training from mental affective events by specific attention set. Usually, meditation can be classified into two categories which

978-1-4799-6801-5114/$31.00 ©2014 IEEE

Y. Wongsawat

Department of Biomedical Engineering Mahidol University, 25/25 Putttamonthon 4, Salaya

Nakornpathom 73170, Thailand e-mail: yodchanan.won@mahidol.ac.th

are "mindfulness meditation and concentrative meditation". Both of them can improve an attention, relaxation and mental health to meditator. The direction that leads to meditation state is a key to classify style of meditation but many people do not know them or practice in wrong direction. [2, 3] Meditation is unclear to practice because it is a self-regulate method and it is difficult for other people to feel or know the result from meditation, which depends on individual meditation state and traits. Moreover, there has been much research which show that there are many factors related to meditation based on brain signal analysis. The brain signal is non-invasive electrical measurement called electroencephalogram or EEG.

From these reasons, the goal of this research is to investigate the meditation state based on scientific approach using binaural beat stimulation. The result will show the relationship indices between EEG and meditation during binaural beat stimulation.

II. MATERIALS AND METHODS

A. System Overview

The comparison between traditional and binaural beat stimulation during meditation practice is a key to prove a relationship between EEG and brain state. The EEG is acquired by 19 channels with 24 bit resolution and 1024 sampling frequency. Participant was examined with three experiments and each experiment has two conditions which are close and open eyes condition. The first experiment is traditional practice and another is meditation practice during binaural beat stimulation. There are two types of binaural beat stimulation that are pure beat frequency and music combines with beat frequency called meta-music. The EEG will analyze using absolute power and coherence which represents in brain mapping in Quantitative EEG (QEEG). The Fig1. shows the system overview.

B. Binaural beat

[4, 5] Binaural beat occurs when left and right of auditory sensory neurons are stimulated with slightly different frequency. Binaural beat was observed by Heinrich Wilhelm Dove in 1839. The highest frequency beat that human can sense is at 30 Hz from the source of frequency around 1000-1500 Hz. A diffuse activating system is a result from listening

to binaural beat which is infonned to reticular system. The reticular system will change the brain wave activity by that is a nature of homeostasis system. The brain will automatically regulate function and activity. The reticular system is initialized at cortical cortex.

EEG.�

Fig 1. System overview

C. Hemisphere Synchronization (Hemi-Sync)

Hemi-Sync is a technology that was developed based on binaural beat phenomena by Robert Allan Momoe in 1974. He proposed that the sound can be mixed with other music but still moderate cerebral activity or change individual emotion from deep sleep relaxation to consciousness. In 1975 Hemi­Sync was patented the scientifically-based and clinically proven audio technology. He combines Hemi-Sync and different types of music to become Meta-music. The example of Meta-music is Einstein dream which is used for improving mental ability via Mozart effect. This music can help attention-deficit hyperactivity disorder (ADHD) and, dyslexia patient. Acutely Meta-music not only reduce negative moods which are anxiety, pain and, depression, but also improve positive emotions such as creativity and concentration.

D. Data Acquisition

The EEG was digitized by BrainDiscovery 24 E from Brainmaster Company Ltd. The device was acquired 19 channels with 24 bits resolution and 1024 sampling frequency. Then, a data rate to computer is 256 samples per second. A band width amplifier is 0.000-100 Hz and common-mode rejection ratio is more than 110 db. Software interface to a device is brain discovery Vl .0.

E. Data Analysis

Data from five participants were analyzed via neuroguide software. [6, 7] A data will be both processed in frequency domain. For frequency domain, the absolute powers of each EEG rhythm were analyzed by using fast Fourier transfonn to compare a nonnal database via Z-score theory. For better analysis, the result was represented in colored picture of a head which is related to brain's area and brain function. A green color presents a nonnal activity of neuron. A red color presents an over activity of neuron in the brain, whereas blue represents an under activity of neuron in the brain compared to nonnal

people. Another parameter that was analyzed is coherence of 19 channels to observe brain connectivity during binaural beat stimulation. Coherence can calculate via mathematical equation of power spectrum which is equation (1).

(1)

Fig 2 Brainmaster (brain discovery 24e)

III. EXPERIMENTS AND RESULTS

A. Participant Preparation

The participants were chosen by considering following conditions: getting enough sleep and healthy, not under effect from medicine, no mental disorder or brain disorder. Participants have to do the experiment once per day and at the same time of each day.

B. Experiment Design

Five healthy participants who are 23-25 years old which are three males and two females took part in this experiment. The experiment is a brain recording to create brain mapping in each state of brain activity and binaural beat stimulation based on Z score of QEEG. A whole system can be separated into three experiments with two conditions. The first experiment is traditional meditation practice. Subjects sit in a rest state and practice meditation with open and close eyes for ten minutes for each condition. The second experiment is pure beat frequency stimulation. Subjects were stimulated by selected beat frequencies, which are 5 Hz, 8 Hz, 12 Hz, and 18 Hz, respectively. These selected frequencies come from frequency rhythm in EEG which is Theta, Alpha and Beta band. Each frequency will be stimulate for 3 minutes and rises up from 5Hz to 18 Hz then falls down from 18Hz to 5 Hz. The second experiment takes 21 minutes for both close and open eye conditions. The third experiment is meta-music stimulation. Subjects were stimulated by the same beat frequencies set in the second experiment but each frequency will combines with natural music. The stimulation is also similar to second experiment which rises up from 5Hz to 18 Hz and dim up from 18Hz to 5Hz in both conditions.

Fig 3 A participant during the experiment

C. Binaural beat generation

Beat frequency comes from the slightly different in original frequency at maximum 1,000 to 1,500 Hz from left and right ear. Then a base frequency that uses to generate beat frequency for stimulation is equal to 400 Hz. Thus another source of frequency will be 405, 408, 412, 418 Hz respectively to generate beat frequency at 5, 8, 12, 18 Hz respectively. Sound pressure was set up at 73 db. for every beat frequency as same as meta-music. Meta-music was modulation from beat frequency and natural music such as dolphin and sea sounds.

D. The comparison between traditional practice and

stimulation in close eyes condition

For pure beat stimulation, there is least increase in alpha power. On the other hand, meta-music obviously increases lower alpha (8Hz) at frontal-midline area compared to traditional practice which shows in table 1.

E. The EEG coherence during meta-music stimulation

Coherence of participant during meta-music stimulation was starts from anterior to posterior of the brain. Moreover, it occurs in every band frequency of stimulation at the same rhythm which is Delta wave which shows in table 2.

F. The comparison between traditionalpractice and stimulation in open eyes condition

For pure beat stimulation, there is slightly increase in alpha power. On the other hand, meta-music obviously increases theta and lower alpha (8Hz) at frontal-midline area compared to traditional practice which shows in table 3.

Table 1 THE COMPARISON BETWEEN TRADITIONAL AND BINAURAL BEAT

STIMULATION IN CLOSE EYES CONDITION

Theta

(5Hz)

Alpha

(8Hz)

Alpha

(12Hz)

Beta

(18Hz)

Traditional Pure beat Meta-music

Table 2 THE COHERENCE OF EACH BEAT FREQUENCY STIMULATION IN OPEN

EYES CONDITION.

Theta

(5 Hz)

Alpha

(8Hz)

Alpha

(12Hz)

Beta

(18Hz)

Delta Theta Alpha Beta H.Beta

Table 3 THE COMPARISON BETWEEN TRADITIONAL AND BINAURAL BEAT

STIMULATION IN OPEN EYES CONDITION

Theta

(5Hz)

Alpha

(8Hz)

Alpha

(12Hz)

Beta

(18Hz)

Traditional Pure beat

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IV. DISCUSSION

1 . 8

The experiments observe a relationship between meditation and EEG by analyzing QEEG in absolute power of each EEG rhythm and coherence compare to normal people database. The results have indicated that, when binaural beat combines with music, it tends to increase the effect of stimulation. Moreover, the effect of binaural beat occurs at frontal midline. For pure beat, there is less effect to relationship between binaural beat and EEG during meditation practice at the first time of stimulation. However, it may improve an effective of binaural beat stimulation for longer period. The last is the effect of binaural beat seems significant for coherence and concordantly to absolute power.

V. CONCLUSION

The relationship between EEG and meditation during

binaural beat stimulation can be observed via absolute power

of theta and lower alpha at frontal-midline region of the brain.

The stimulate frequency is significant related to power of

frequency in EEG rhythm. Coherence direction is affected

from stimulation which starts from anterior to posterior region.

Moreover coherence occurs in every beat frequency .

ACKNOWLEDGMENT

This research is supported in part by Mahidol University.

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