Brains have a reputation for outperforming the most expensive computers, and yet they accomplish even their most spectacular feats at a leisurely pace. Most computers are restricted to performing one or a few calculations at a time, which they then replicate billions of times every second to get their results. Brains, on the other hand, perform millions of calculations at the same time but only step forward through those calculations twenty or so times a second. These steps are locally synchronized and consequently show up as pulses of electrical activity which we call brain waves.
For example: The video frame rate changes 30 times every second, which is faster than the brain processes an image, resulting in the illusion of motion. This cycle rate is associated with hyper-attention (Gamma waves) and may be a part of what captivates our attention.
Brain waves are clustered into four primary groups; Beta, Alpha, Theta, and Delta. There is much information available on what these groups indicate for brain function, here it will suffice to say that they range from peak concentration (Beta) to deep sleep (Delta). Brain function is easily entrained by an external source of these frequencies. There are many audio and visual products available that do just this for purposes ranging from helping insomnia to guiding meditation practice to focusing concentration and workflow. They all follow the same basic principle of imposing a rhythm that the brain quickly drops into lockstep with, thereby affecting brain function. For a brain that is dysregulated, brain wave rhythms can help focus attention appropriately, from sleeping at night to lessening hyperactivity.
The configuration of our brains was established in an environment that had very little rhythmic activity, especially above several cycles per second. It is very unusual for a natural system to cycle more quickly than this. Therefore our brains were quite safe evolving to operate at frequencies above this rate. Our modern environment is just the opposite and is filled with rhythms that are auditory, visual, kinesthetic, electromagnetic, or otherwise. Many toys are designed to operate in this frequency range, and it is not surprising that children find them captivating. It is therefore quite handy to recognize these rhythms, and what they represent in terms of entraining and influencing brain function.
Fortunately, we can represent these frequencies in the audible range so it is easy to develop the skill to recognize them. An effective method for doing so is to get two frequencies to ‘beat’* together at the brain wave rhythm rate. I have included links to four 30-second audio files which demonstrate these rhythms. The files are based on pure Sine waves around 440 Hz (A) and are therefore a little hard on the ear, however, they accurately represent the frequencies of interest. If you listen to them several times you should begin to recognize the same patterns in your environment.
On 440 Hz carrier wave
If you have had seizures, do not listen to these samples.
Once you become familiar with these frequencies, you will recognize them all around you, and even where and how they are used to intentionally direct our attention. Think of Las Vegas and even music. More importantly, you may begin to see them influencing your child or even yourself unexpectedly. I have seen hyperactive children staring mindlessly into blinking lights in the mid-theta region. These rhythms are not bad, however, it is helpful to remember that they are not natural and to recognize the influence they may be exerting on brain function.
* Beat Frequencies are changes in volume at the rate which is the difference between two tones. The two frequencies interfere with each other to either amplify or cancel out the tone, at the beat frequency rate. Beat frequencies are very useful for representing frequencies below the audible range. For example, if you have two tones, one at 440 Hz. and one at 444 Hz. they will beat at 4 Hz. or 4 cycles per second, a deep delta pattern. If you again take the 440 hz (A) and combine it with a 465 hz tone, you get a much higher pitch beat of 25 hz which is in mid Beta, useful for concentration. An interesting thing to do with brain wave beat frequencies is to listen to them through headphones*, where different frequencies pass into each ear. The brain then electrically combines the tones into the beat, so that it becomes an electrical beat rather than an audible beat. This can quickly change the state of the brain and is quite disorienting, but lots of fun.
*If you have had seizures, do not listen to these samples, especially through headphones