In 1839, physicist Heinrich Wilhelm Dove discovered that signals of two different frequencies playing a specific tone in one ear, and a slightly different tone in the other ear, make our brain detect the phase variation between the frequencies. Binaural beat is how we call the difference between these two signals. For instance, your right ear is presented a 100 Hz frequency and your left ear a 110 Hz, your brain perceives a third frequency pulsing at 10 Hz, the difference between the two frequencies. Brainwaves receive a direct influence by binaural beats, so that the listener may experience different states such as:
- deep meditation
- deep sleep
- creative zone
- deep focus
Every moment in our brain is characterized by infinite bioelectric processes. A huge number of signals travel continuously from one neuron to another, carrying specific informations with it. Some of these signals can be recorded and reported on an electroencephalogram (EEG) like waves, being rhythmic fluctuations of tensions among brain components. All brainwave states are present in varying quantities in different parts of the brain. There are five common states for brain waves:
The frequency of these waves is relative to the state of consciousness and this state determines a resulting type of emotion and/or mental function. The state of consciousness is relative to the dominant waves at a given moment.
Delta (0.1 - 3.9 Hz)
The lowest frequency of brain waves, which is usually reached only in the stage of deep and dreamless sleep or in trance (even hypnotic); mind in this state is not active, man is in a state of unconsciousness and has no rational control. It is thought that this state is connected to what Jung called "collective unconscious".
Theta (4.0 - 7.9 Hz)
Brain waves in this category are those of REM sleep (rapid eye movement, the stage of sleep in which we dream) which are associated with states of very high creativity, healing, intuition, deep understanding, lucid dreams. Usually, this category is reached in the waking state only with deep meditation: experiments with EEG have found Theta waves in Zen monks during their practices. Some psychologists believe that this state is the gateway to the subconscious.
Alpha (8.0 - 12.9 Hz)
Brain waves in this category are those that accompany states of relaxation and deep concentration. In the high end of this category we find states of concentration related to what can be called "super learning" while in the low end we find states of relaxation such as moments before sleep, light meditation, introspection, etc. In an even lower range, just before the Theta category, there are mental conditions associated with inner peace and satisfaction.
Beta (13.0 - 40.0 Hz)
This is a quite fast range of frequency, it corresponds to the state of normal consciousness and is associated with attention, wakefulness, concentration and physical and manual activity; for most people and most of the time beta brain waves are more prevalent than others. In the high end of this category (above 30 Hz and even over 40 Hz) we can find states of discomfort, stress, anxiety, neurosis, etc.
Gamma (40.0 - 100.0 Hz)
Gamma brain waves are the fastest brain waves produced inside the brain. They are evidence of an achieved peak concentration, when the brain is intensely focused and very actively engaged in solving a problem. They are related to tasks with high cognitive processing. They help process information. People with mental or learning problems tend to have lower than average Gamma wave activity. States of happiness show high peaks in these brain waves.