The experience we hear that's known as 'Binaural Beats' is actually an illusion.
When two separate frequencies are played close to each ear eg. 392hz on the right and 400hz on the left, the brain interprets the sound as one slow rhythmic pulse of 8hz. This frequency is the mathematical difference between the two frequencies: 400hz - 392hz = 8hz.
The brain then ‘follows’ this frequency to produce brainwaves of the same frequency, thereby altering the brainwave state of the individual.
This process, known as entrainment, is measurable using Electroencephalography (EEG), a scan where electrodes are placed on the head and the brainwave patterns and frequency measured.
So, even though what we hear is our brain's interpretation of the sound, the slower brainwave frequencies induced are very real, and initiate a variety of relaxing mental states.
The specific brainwave patterns for sound therapy are:
- Delta pattern: The delta pattern operates at a frequency of 0.5–4 Hz and are the slowest brainwaves. They are usually produced during the deep stages of dreamless sleep, and are linked to regulating unconscious bodily processes: heart beat regulation, kidney and digestive functioning and hormone release. The benefits associated with Delta waves include: better sleep, boosted immune system functioning, improved healing and increased empathy.
- Theta pattern: The theta pattern operates at a frequency of 4–7 Hz. It is associated with meditation, the subconscious mind, intuition, daydreaming, creativity, emotional response, inability to focus or concentrate, and deep relaxation. It is also the brainwave state experienced during hypnosis, and sleep in the rapid eye movement (REM) or dream phase.
- Alpha pattern: The alpha pattern operates at a frequency of 7–13 Hz and is associated with relaxed wakefulness or can occur during light meditation. The alpha wave is typically produced by the right hemisphere of the brain, but often is synchronized across both right and left hemispheres. The alpha range becomes dominant when a person closes their eyes and focuses on relaxing. Alpha activity is linked to drowsiness, calm, and boosted mood. The alpha state facilitates a bridge between conscious thought and the unconscious mind, and plays an important role in our sleep-wake cycle. Researchers believe that it is a natural cure for anxiety and stress.
Other brainwave patterns are:
- Beta pattern: The beta pattern operates at a frequency of 13–30 Hz, and is associated with normal, wakeful consciousness. This frequency range may help promote concentration and alertness, but it can also increase anxiety in the higher end.
Low Beta activity of 12 Hz – 15 Hz is often associated with quiet, focused, introverted concentration.
Mid-Range Beta Waves of 15 Hz – 20 Hz are commonly associated with increases in energy, anxiety, and performance.
High Beta Waves in the 18 Hz – 30 Hz are associated with significant stress, anxiety, paranoia, high energy, and high arousal.
- Gamma pattern: This frequency pattern is the fastest at a range of 30–50+ Hz. They are able to link and process information throughout the entire brain. Gamma wave activity has been associated with having increased problem solving skills, increased/peak focus, compassion, self-control, and intelligence. They have also been observed in short bursts during REM sleep. They play a role in helping us perceive reality, with memorisation, and are associated with ‘Lightbulb’ moments of inspiration, higher meditative states and transcendant moments of epiphany.