Brainwave Entrainment And Isochronic Tones: How Do they Work?

If you’ve landed on this site, you’re presumably curious about using brainwave entrainment and isochronic tones, perhaps to improve your meditation sessions, explore altered states of consciousness, or solve some problem or other. While you don’t have to know how these technologies work to benefit from them, they’re fascinating all the same, so if you’re not sure exactly what brainwave entrainment or isochronic tones are, then read on.

Measuring Brainwaves

When brain cells (neurons) communicate with each other, they collectively generate a large amount of electrical activity, which can be measured by means of medical equipment such as an electroencephalogram (EEG) machine. This activity is cyclic in nature, taking the form of waves of activity – hence the name ‘brainwaves’.

Like other types of waveforms, brainwaves are measured in terms of Hertz (Hz), or cycles per second. Brainwave activity is classified into various ‘bands’ on the basis of frequency, and these bands are associated with different physical and mental states. The main brain wave activity bands are as follows:

  • Delta brainwaves (< 4 Hz) – Delta waves occur naturally in deep, dreamless sleep. They are associated with the regeneration of the physical body. Experienced meditators may also produce delta waves when in very deep trance states.
  • Theta brainwaves (4 – 7 Hz) – Theta waves are linked with deep trance meditation and hypnotic states, as well as light sleep.
  • Alpha brainwaves (8 – 12 Hz) – Alpha waves are produced in states of light relaxation and meditation, daydreaming, hypnosis and visualisation. Just closing your eyes will naturally cause your brain to go into the alpha state.
  • Beta brainwaves (12 – 30 Hz) – Beta waves are linked with normal waking consciousness, when you’re in a state of alertness and focus.
  • Gamma brainwaves (> 30Hz) – The existence of gamma waves is disputed by some researchers, but where recognised they are linked with states of transcendental consciousness.

Note that the boundaries between these bands aren’t agreed on by all researchers, and are approximate, rather than absolute.

What Is Brainwave Entrainment?

Many people wish to be able to voluntarily enter the mental states associated with different brainwave frequencies, and this ability can be learned. However, some find it difficult to learn the necessary control of their mental focus, or simply don’t have the time to develop it. This is where brain wave entrainment can come in useful.

Researchers have found that by using brainwave entrainment, brainwaves of the desired frequency can be induced at will – and so can the mental states associated with them. Brainwave entrainment takes advantage of the so called ‘frequency following response’, which is the brain’s natural tendency to synchronise with the frequency of a periodic external stimulus, such as sound or light pulses, if the rate and pattern of those stimuli is close to those of the brain’s own rhythms. If you listen to a sound recording which contains frequencies that correspond to those of the alpha state, for example, your brain will begin to produce predominantly alpha waves as you listen (it may take some practice to sustain the state).

Although brainwave entrainment has only been studied scientifically since the 20th century, it isn’t a new phenomenon, and has been used by cultures throughout the world for centuries (in the form of shamanistic drum beats, for example).

Types of Brainwave Entrainment Technology

Brainwave synchronisation is most often achieved using sound, light, or a combination of the two. Other types of stimuli can be used too; basically anything that pulses in an appropriate rhythmic manner has the potential to be used for entrainment. However, aural methods are the most convenient and economical for most people, so we will focus on those here. There are three main types of sound-based brainwave stimulation: binaural beats, monaural beats and isochronic tones. These work slightly differently, but all produce good results.

Binaural Beats

Binaural beats are the oldest and most thoroughly studied type of aural entrainment method, and are probably still the most popular. They were originally discovered in 1839, by Heinrich Wilhelm Dove, researched in a scattered manner throughout the 20th century, and first seriously examined in the 1970s, by Gerald Oster.

Binaural beats are sound pulses that originate inside the brain, when two pure sounds of different frequencies are played through headphones (one sound to each ear). These two tones must be below 1000 – 1500Hz, and the frequency difference between them around 30 Hz or less. For example, you might listen to a 300Hz tone in your left ear, and a 308 Hz tone in the right. The brain will process the sounds and an 8Hz pulse will be perceived within the head (that is, the pulse will repeat eight times per second). The brain will then entrain to this pulse, producing brain waves of a similar predominant frequency. Sometimes the two tones are masked to some extent by using pink noise, ambient music, running water or similar sounds.

Although binaural beats are so widely used as to be almost synonymous with brainwave entrainment in many people’s minds, they’re not usually the most effective method.

Monaural Beats

The difference between binaural and monaural beats is that with monaurals, the two sine waves are mixed together before entering the ear. In this way a pulse is produced with the frequency of the difference between the two tones, but unlike with binaural beats, the brain itself does not have to produce that third sound. Many people believe that this process is easier on the brain than binaurals, and more effective, since the monaural waveform is more clearly defined, and thus has a stronger entrainment effect.

Monaural beats may be played with or without headphones, although it is best to use headphones if possible, to reduce distractions.

Isochronic Tones

Isochronic tones are the third and newest entrainment method, and are the most effective in most cases. They consist of a single tone of a specific frequency that plays at clearly defined intervals. These intervals are varied, depending on the effect required. They also differ from monaural beats in that monaurals consist of a single pulsed sine wave, whereas isochronics feature completely separate pulses with a very clear interval between each one. These discrete pulses have been found to be extremely effective in entraining the brain to the desired frequency.

Like monaural beats, isochronic tone recordings don’t require the use of headphones, although again, they’re recommended if possible.

The following video illustrates the difference in the waveforms of these technologies – you can see how much more clearly defined the isochronic tones are in comparison to the others:

Which Are Best – Binaurals, Monaurals Or Isochronics?

In most instances, isochronic tones are the most effective method, because the ‘spaced out’ nature of the pulses has the strongest entrainment effect – when listening to an isochronic tone recording, your brain should synchronize with it more quickly and deeply than with binaurals or monaurals. Unlike binaural beats, isochronic tones can be used without headphones, which can be more convenient and comfortable for many people. They can also be used to synchronize each hemisphere of the brain individually, which is required for some purposes.

Isochronic tones aren’t always best however; some people find the more ‘jagged’ noise they produce to be distracting or irritating (especially at the deeper theta and delta frequencies), and they can’t be hidden in pink noise and other sounds in the same way that binaural beats can, because the tones must be audible to be effective.

Personally, I prefer isochronic tones for most brainwave entrainment purposes, followed by monaural beats, then binaural beats. However, all three methods do work, and I recommend experimenting with all three to find what suits you best.

Uses Of Brainwave Entrainment

Brainwave synchronization technologies have many uses. They are popular with those who wish to explore altered states of consciousness such as lucid dreaming or astral projection, or who wish to develop extra sensory abilities like telepathy or remote viewing. They are also used to normalize mental functioning, such as in the treatment of depression, anxiety or sleep problems, or to enhance mental performance and creativity. Some also use brainwave entrainment to boost their physical health or healing abilities.

The articles on this site explore many of these uses in more depth, and if you want to start trying out isochronic tones or other types of brainwave recordings yourself, check out The Meditation Club. I personally like using their alpha and theta meditation recordings regularly, and am experimenting with some of the other tracks. They’re all fully guaranteed, and you can get some free samples too.

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