As discussed in the last chapter on Brainwaves Frequencies, in order to understand how Brainwaves are altered, we need to answer following two questions :
(1) How any external sound can alter our brain wave frequency? We listen so many sound everyday. All of them must have an effect on our brainwave. Then how come a particular sound of a particular frequency will bring change in our brainwave’s frequency?
(2) The frequency of alpha, theta and delta are in the range of 1 to 13 Hz whereas human ears are capable of listening to sounds only within the frequency range from 20 to 20,000Hz . So how can we listen an external sound that produce an effect within 1 to 13 Hz to attain alpha, theta or delta level of conscious?
Let us discuss these questions one by one.
First of all, we need to understand how an external sound can alter our brainwave’s frequency.
An external sound alter our brainwave’s frequency with the help of a simple natural phenomena known as ‘Entrainment’.
Please notice the spelling: It is NOT : Entertainment
It is ‘Entrainment’
Entrainment is defined as “a synchronization of two or more rhythmic cycles”
When two closely related rhythmic cycles interacts with each other, they synchronize with each other resulting in the conservation of energy. This is known as Entrainment.
It is actually a very common phenomena. Let us understand it with some real life examples.
Entrainment was first of all discovered by a Dutch scientist Christian Huygens in 1665 (it is that old !). One of the experiments that led to this discovery was when Huygens set up a room full of pendulum clocks and got them all started one at a time. He found that when he came back to the room a day later, the sway of their pendulums had all synchronized. From this, he extrapolated that entrainment represented the phenomena of synchronization of closely related rhythmic cycles on their interaction with each other to conserve energy.
So the principal behind entrainment is very simple and has universal appeal :
“Any two vibrating bodies will entrain if exposed to each other for long enough”
i.e. they will synchronize if exposed to each other for long enough”.
It’s true of clocks and electric driers sitting in close proximity to each other; it also describes the way musicians manage to play in time together in groups, the way women’s menstrual cycles fall into synch when they live with one another, and the way our body systems interact.
Within our bodies, our various rhythmic systems never fight each other—they always fall into synchronized rhythms—and a lack of synchronization, like in the case of a bad heart valve that is not quite timed to the flow of blood, leads to sickness. It also seems to be the case that these body systems entrain, become synchronized, to the environment, to its oscillating features. There is overwhelming evidence that circadian rhythms (our biological clock) keep us entrained to the rhythms of the earth relative to the sun, and that various systems within our bodies entrain to repetitive stimulation. Other examples are the way that two people walking next to one another will fall into step with each other, or the way that people clapping in a full room will synchronize their claps given enough time.
Entrainment and Brainwaves
So what actually happen in the case of brainwave is that an external audio stimuli (specialized sound with a particular frequency) is repeatedly played which result in the entrainment of that brainwave with the external sound. As this process is continued for sometime, the brainwave is tuned to the frequency of external sound and thus achieve the particular frequency level of that sound (alpha, theta or delta). This is known as brainwave entrainment.
This entrainment of brainwaves is also called as Frequency Following Response (FFR) in many literature.
So the methodology of brainwave entrainment is very simple. Just listen to the sound of your desired frequency using headphones and soon that sound will entrain your brainwaves to its own frequency level. For example, if a person is in beta stage (highly alert) and a stimulus of 10Hz is applied to his/her brain for some time, the brain frequency is likely to change towards the applied stimulus. The effect will be relaxing to the person. This is what we call called the frequency following response.
When the brain’s state is close to the applied stimulus, entrainment works more efficiently. Thus, when doing a sweep from one frequency to another, the starting frequency should be as close to your current brain state as possible. The sweep speed should be such that your brain’s state changes steadily with it, so that the difference never gets very large. In practice, it is difficult to determine your brain state without extra equipment (like EEG devices). However, you can quite safely assume that during the day your brain is in the beta stage (about 20Hz) and you can start the sweep from there. If you are already somewhat relaxed, you can use a start frequency of 15Hz or a few Hz lower.
So this is all you need to know about brainwave entrainment, the method of altering your brainwave frequencies.
However, we still need to answer another important question. From where are we going to produce these specialized sounds with a frequency range of 1-20 Hz and how we can make them hearable to human ears when it can only listen the sounds of the frequency between 20-20,000 Hz ?
The answer to this question lies in a specialized sound known as Binaural beats.