Brainwave entrainment is any practical techniques that aims to induce specific brain wave frequency range or brain wave types using external stimulations. This process is called the frequency following response that the brain is fully adaptable and trainable and be able to respond to the external stimulations. The state of the mind can be influenced by brain wave entrainment and changed into a dominant brain wave type (alpha, beta, theta, delta or gamma) towards the frequency of external stimulus. Brain wave entrainment techniques or brain wave synchronization technology is widely applied in order to enhance the state of mind for one specific purpose (e.g. increase cognitive function, improve memory, reduce stress, facilitate meditation). It can be used to facilitate diagnosis and treatment of certain cognitive impairments and other medical conditions.

There are five major types of brain waves with different frequency ranges corresponding to different mind states (see post “Brain Waves, Brain Chemical Systems and Memory”). Alpha wave (8-12 Hz) dominates the mind when the brain is in wakeful relaxation mode with consciousness. Beta wave (12-40 Hz) corresponds to an active busy mind with active concentration, cognition or with anxious thinking, stress and anxiety. Theta wave (4-8 Hz) dominates when the brain is in deep relaxation mode just below the surface of consciousness. Delta wave is the slowest brain wave (0-4 Hz) typically associated with deep dreamless sleep without REM or NREM. Gamma wave (30-100 Hz) is the fastest brain wave, typically seen in higher mental states (intense complex higher level of cognitive activities). One essential feature of gamma wave state is that the brain is not being disturbed by stressful thoughts and anxieties. Brain wave entrainment helps the brain to enter the intended mode for which it is needed for cognition enhancement, mood optimization, relaxation maximization, or energy restoration. Studies have validated the beneficial effects of brain wave synchronization in improving physical, mental and even spiritual well-being. Research confirm the benefits of brainwave entrainment on improving learning, memory, IQ, treating cognitive impairment, mental illness (e.g. depression), reducing migraine.

Brain wave entrainment can be accomplished using auditory, visual, or tactile stimulation – all of which has been found to be able to induce different brain wave types and brain wave pattern. In fact, the brain can be affected by any kind of rhythmic stimuli. Clicks, drum beats, light flickers and even physical vibrations or electric pulses have all been found to effectively entrain the brain. Auditory approach is the most well established and dominant external stimulus. Visual stimulus are not as widely used as auditory method, but is generally good complement to aural entrainment. Audio-visual entrainment combines auditory and visual stimulus to guide the brain into various states of brain wave activities. Many commercially available brain wave entrainment uses proprietary software. They are available for PC or mobile device and are specially designed to use combinations of audio, visual (usually photic stimulus) stimulation. Photic stimulation is the use of flashes of light in conjunction with sound at the same time. In order to trigger the brain into the intended state of mind, the frequency of the external stimulus need to be configured correctly and be precisely timed.

There are three major types of Aural entrainment: binaural beats, monaural beats, and isochronic tones. They can be used in combination in any specifically designed brain entrainment products. Binaural, Monaural and isochronic, each have unique benefits. Combining them would add dimensions of use and get the most efficient and effective intended results.

Binaural beats is the third signal brain is capable to create when two audio signal with close but different frequency is presented to the brain with one frequency to each of the ear. For example, if a sound wave with frequency of 100 Hz is presented to the right ear, and a frequency of 105 Hz auditory signal is presented to the left ear, the brain will create its own third frequency of 5 Hz – the exact difference between the two frequency. The brain’s frequency following response will guide or induce the brain into a state of mind with the dominant theta waves (4-8 Hz). Research has proved that binaural beats can effectively entrain the brain to begin resonating in tune with the specific brain wave it intended to produce. The technique can quickly and easily guide the mind into any state. Binaural beats could help induce relaxation, meditation, creativity, and other desirable mental states.

Monaural beats are produced when two tones were combined digitally and naturally before the sounds reached both ears (stereo headphone is not required). This is different from binaural beats. Binaural beats effect is created by the neural output from the ears and the third frequency is produced within the brain. Monaural beats occur external to the ear and is created before the signal is perceived by the ear. There is no third frequency created after perception within the brain. Monaural beats are the arithmetic sum of the amplitude of waveforms of the two tones as they add or subtract from one another, making the sound louder,  quieter and louder again.

Isochronic tones contain a single tone which can be turned on and off in a unique and accurate pattern. Isochronic tones differ from binaural and monaural beats in that it does not require the combination of two tones. The “beat” is created manually by turning the tone on and off. Isochronic beats can induce strong response in the brain cortex. It has been found to work effectively for people who do not respond well to binaural beats. Isochronic tones are widely regarded as as one of the most effective tone-based brain entrainment technology.

Music modulation and audio filtering is a relatively new method of aural brain wave entrainment utilizing complex musical sound tracks. Modulation is done by rhythmically adjusting one of the elements in the music. This could be the volume of the music, frequency band selection. Frequency band selection is a patented technology from mind workstation – a commercially available brain wave entrainment – which can modulate only one part of the sound file. For example, only parts of the bass and cello in an classical symphony is modulated, leaving the viola and violin not affected.

Audio-visual entrainment uses flashes of lights and pulses of tones to generate various states of brain wave activities. Various methods can be used to create light stimulations including the use of LED glasses, computer screen flashing and others.

Brain wave entrainment technology maximize the potential of brain wave synchronization at the macroscopic level. At macroscopic level, neural oscillations are simultaneously activated in different areas of the brain. One notable areas of macroscopic synchronization is the thalamocortical network which is implicated in the generation of alpha, beta, and gamma waves.