Technical Information

What are Brainwaves? | Stimulating the Brain | Technical Info | A Brief History

Many people have asked to know more about our unique approach to brainwave entrainment. On this page we are going to attempt to explain how some of these techniques work and why we use them. It may get a bit technical at times, but should be informative. If you have any further questions please email us or visit our online community.

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Brainwave Entrainment Methods

The most well known form of brainwave entrainment is binaural beats, where a slightly different tone is presented into each ear. When pure tones are mixed together, their waveforms add and subtract from one another, resulting in a pulse. In the case of binaural beats, the two tones are mixed by the brain itself (one in each ear). The pulses, called "beats", formed by mixing these tones is what causes entrainment to occur. As you learned in the entrainment section, brainwaves are affected by rapid pulses of sound, light or other sensory stimuli.

Fig. 1

EEG Recording. Spectrogram View (4-30), ~1.2 minute time lapse, middle of an Alpha session from the NeuroProgrammer

But since any kind of pulse can be used to entrain the brain (click here for details), there are many other, more effective methods that allow more control than binaural tones. One is Isochronic tones, where a tone is manually spaced, turning on and off in a precise pattern. Another is called "Photic Driving", which involves doing the same thing with Light, using LED Light Goggles or a flashing screen (like a strobe light). Clicks, drums, physical vibrations and even electric pulses can be used to entrain the brain. In fact, photic, tactile and click-based entrainment were discovered long before binaural beats. Today, there are even more complex methods for embedding pulses into music and white noise.

Some entrainment methods do not rely on speaker assignments, and therefore can be used without headphones or any special speaker assignments. For veteran users of brainwave entrainment, this may seem strange since headphones have always been a traditional part of the brain training experience. The reality of the matter is that headphones have never been required for use with anything except Binaural beats. Monaural beats can be used very effectively without headphones. So can pulses, clicks and light stimulation. In fact, many ancient cultures used Drums to enter deeply relaxed 'trances' during Shamanic rituals. Though they may not have called it brainwave entrainment, the rhythmic stimulus of the drum could have been the cause of the "trance-like" states reported during such rituals.

The Entrainment Technology of NP2

NP2 is capable of producing all known forms of Audio and Visual entrainment, including Monaural & Binaural beats, Pulses, Filters, screen flashing and can even connect with AudioStrobe goggles for focused photic stimulation. We have also developed a range of more modern methods such as Crossfeed, which feeds sound between speakers, similar to how an auto-panning function would.

The sessions in NP2 have been meticulously designed to produce the greatest neural response during EEG tests. In order for the brain to be effectively entrained, every Pulse or "beat" must leave an individual electrical imprint on the brain, called a Cortical Evoked Response. To do that, the depth or "intensity" of the pulse must be as large and abrupt as possible.

Below is an example of an Isochronic entrainment pattern. Notice how individual and separated each pulse is.

This type of stimulation produces incredibly powerful electrical responses in the brain, more noticeable than any other form of stimulation. But, other methods do have their advantages. Entrainment can be effectively embedded into music and white noise, greatly enriching the entrainment experience, and usually creating a more pleasant, relaxing experience. Below is an example of a single filter (volume modulation) applied to music:

Although the pulses are not as individual, they are consistent and large enough to have a significant impact on the brain.

Why not use just Binaural Beats?

Binaural beats have become very popular over the years, so much so that for many people the idea of "brainwave entrainment" is inseparable from them. But there are many other ways to stimulate the brain, many of which are more effective.

We use more methods than just binaural beats for many reasons:

1) Binaural beats require headphones or special speaker assignments. This can be difficult for people who do not have headphones or find them uncomfortable.

2) Binaural beats are not capable of entraining the Hemispheres individually (because they require BOTH ears). This can be a major disadvantage because many of the modern entrainment protocols used in clinical work today involve separate stimulation to each ear, useful for deeper meditation, cognitive enhancement and particularly for depression and ADD reduction.

3) Binaural beats are not as effective as more modern entrainment methods, though they do remain the most interesting. Dr. Gerald Oster, in the 1973 issue of "Scientific American", introduced binaural beats to the main stream. According to Oster, because of the way the brain processes binaural beats, the depth or intensity of the resulting "beat" is only around 3db, or 1/10th the volume of a whisper (which is why the "beats" are usually so hard to detect). He concluded that binaural beats produced very small evoked potentials within the auditory cortex of the brain, while monaural beats and other methods produced far greater potentials.

In the brain, a binaural beat would look something like this:

Notice how shallow the wave is. The above pulse would be barely detectable. On the other hand, a monaural beat, or sine wave pulse, looks like this:

Which do you think will leave more of an electrical imprint on the brain, based on what we know about cortical potentials? It is because of these differences that it has been concluded by many researchers, such as David Siever, that binaural beats are not likely to produce much actual brainwave entrainment at all.

Yet many studies have shown that binaural beats do produce a limited amount of brainwave entrainment. A study done by Dale Foster (available here) showed that binaural beats DO entrain the brain. Unfortunately, the beats did not produce any more of the target brainwave (alpha) than an artificially generated surf sound, which was acting as a control. This study shows that while binaural beats can be useful, additional techniques are needed to entrain the brain to the levels most people need. This is exactly what we did in NP2.

Hemispheric Synchronization

Hemispheric Synchronization is a byproduct of nearly all types of brainwave entrainment.

In 1980, Tsuyoshi Inouye and associates at the Department of Neuropsychiatry at Osaka University Medical School in Japan found that photic stimulation in the alpha range produced hemispheric synchronization. Dr. Norman Shealy later confirmed the effect, finding that photic stimulation produced "cerebral synchronization" in more than 5,000 patients. In 1984, Dr. Brockopp analyzed audio-visual brain stimulation and in particular hemispheric synchronization during EEG monitoring. He said "By inducing hemispheric coherence the machine can contribute to improved intellectual functioning of the brain."

There is similar evidence that CES (electrical stimulation), motion systems, acoustic field generators and even floatation tanks can increase EEG symmetry.

The NeuroProgrammer takes hemispheric coherence a step further by delivering different stimulation to each ear in certain sessions in order to correct common hemispheric asymmetries. For example, depressed individuals tend to have an overactive right (emotional) brain hemisphere, so the depression reduction session acts to decrease right brain activity while increasing left, the end result being a more coherent, healthy and well balanced brainwave pattern.

More information available in the NP2 Documentation.

For more information

See the Technical FAQ.

Further Reading

Bermer, F. "Cerebral and cerebellar potentials." Physiological Review, 38, 357-388.

Chatrian, G., Petersen, M., Lazarte, J. "Responses to Clicks from the Human Brain: Some Depth Electrographic Observation." Electroencephalography and Clinical Neurophysiology, 12: 479-487

Gontgovsky, S., Montgomery, D. "The Physiological Response to "Beta Sweep" Entrainment." Proceedings AAPB Thirteenth Anniversary Annual Meeting, 62-65.

Oster, G. "Auditory beats in the brain." Scientific American, 229, 94-102.

Shealy, N., Cady, R., Cox, R., Liss, S., Clossen, W., Veehoff, D. "A Comparison of Depths of Relaxation Produced by Various Techniques and Neurotransmitters by Brainwave Entrainment" - Shealy and Forest Institute of Professional Psychology A study done for Comprehensive Health Care, Unpublished.

Siever, D. "Isochronic Tones and Brainwave Entrainment." Unpublished, but available through his book the Rediscovery of Audio-Visual Entrainment.

Walter, V. J. & Walter, W. G. "The central effects of rhythmic sensory stimulation." Electroencephalography and Clinical Neurophysiology, 1, 57-86.

See References for more.

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