How Brain Entrainment CDs Really Work

So, you've read the claims for brain entrainment CDs, but you're skeptical. Sure, listening to music can relax you. Everyone knows that! But how will listening to a CD make you smarter or more energetic?

In this article, we're going to look at the some of the science underlying the Brain Evolution System and earlier products like Equisync and Brain Sync.

There are many brain entrainment CDs on the market, but all of them trace their origins back to Hans Berger's development of the EEG machine a century or so ago. By making it possible to study electrical activity in the brain, Berger's machine enabled researchers to explore brainwaves and their relationship with consciousness.

Brainwaves are patterns of electrical activity. While everyone's brain is unique, all brains have some qualities in common. For instance, in deep sleep, your brainwaves settle into a characteristic cycle with peaks of electrical activity occurring between one and four times a second -- 1-4Hz. When you're awake and relaxed, another kind of pattern emerges, with cycles at 8-12Hz.

Neuroscientists recognised these brainwave frequencies and gave them familiar names. The deep-sleep pattern is called a delta wave, and the relaxed-concentration one an alpha. Other states include beta (alert, active, anxious), and theta (associated with meditation and creativity). Soon, there were attempts to deliberately 'switch on' different brainwave frequencies -- putting insomniacs into a relaxing delta sleep, or teaching manic, hyperactive types to chill out in their own alpha waves.

Various methods for controlling brainwaves have been explored, but the most effective turns out to be the simplest. If you subject the brain to a rhythmic stimulus, it will tend to go into the corresponding brainwave frequency. Need some delta sleep? Find a 1-4Hz stimulus, and in a few minutes your brain will do the rest of the work. This so-called frequency following response (FFR) is the basis of all brain entrainment.

If you're looking for a convenient stimulus, music and sound are clearly a great choice. But there's a basic problem... our ears are calibrated wrongly! For most people, the lowest audible note occurs at 20hz. It's difficult to get a really low-frequency stimulus into the brain via the ear.

But there are methods. Back in the 70s, work began on entrainment using binaural beats, which still provide the basis of older systems like Equisync, Brain Sync, Holosync, and a few others.

Binaural beats rely on stereo headphones. Sounds of slightly different pitch are played in the two earpieces. Because the brain cannot distinguish between the two, it interprets the difference between them as a low-frequency 'beat note' providing stimulation at the desired brainwave frequency. Additionally, research suggests that the extra effort made by the brain to interpret a single tone from the two different 'sound images' can improve synchronization between the two hemispheres.

Of course, CD developers choose tones that will produce beat notes at exactly the right frequencies, perhaps with variations intended to take the listener through different brainwave states. Commercial CDs usually layer on atmospherics and background music to make the computer tones which produce the binaural beats more enticing -- and modern programs like the Brain Evolution System and its 'DEAP' architecture combine binaural beats with other, subtler entrainment mechanisms for a more profound and complex experience.

But the underlying concept of entrainment remains the same -- you're literally reprogramming your brainwaves using the power of sound.