(Illustration by Richard Daub)

Brainwaves: a refresher course.

We've all heard the term "brainwaves" bandied about, but does it mean? What, exactly, inside the brain is waving? Well, as you know from basic science class, any form of electromagnetic energy (visible light, sound, microwaves, X-rays, and so on) exists as waves. Waves sometimes act like particles, but to understand why would require a detour into quantum physics and there's a big KEEP OUT sign there and it's not important to our discussion here anyway. For now, think of energy as existing in nice, perfect sine waves, like the kind you seen displayed on an oscilloscope.

As we go through our day, our metabolic rate changes due to an internal clock, to the coffee or alcohol we put into our bodies, the amount of sun we get, and a whole host of other things. Our brains reflect this speeding up or slowing down by emitting electrical energy at higher or lower frequencies. This is in the form of waves, but they are sound waves, which are mechanical, longitudinal waves that require a medium in which to operate. Let me explain that last sentence. A longitudinal wave doesn't go up an down like an electromagnetic wave, it compresses and contracta, like a slinky or an accordion. (Confusingly, it can still be modeled on as an up-and-down signal, but the ups and down now mean frequency rather than amplitude. I'll leave it at that for our purposes) The frequency of a sound wave is the number of times a peak passes by a certain point per unit of time (say, a millisecond). With sound, our subjective experience of a change in frequency is a change in pitch: A high-frequency sound has a higher pitch than a lower-frequency sound.

At either end of the table, so to speak, the pulsating waves of energy cease to be audible to us, but their effects can still be felt at times. At the high end, we get into frequencies our ears are happy to pick up, but our eardrums are not sensitive enough to vibrate when hit by them, and our brains are just not constructed so as to translate them into a "sound" at that level anyway. Same thing happens when you drop below a certain frequency, the ultra-low bass sound seems to fade and then disappear and it gets deeper. All animals have difference ranges of frequencies to which their ears and brains have adapted to be sensitive, depending on their evolutionary needs and pressures. Dogs famously can hear higher frequencies than we can, but they can only hear low sounds as well as humans. Cats do even better than dogs on high frequencies, and can also hear into a lower register than we (or dogs) can. Cats, obviously, rely upon sound greatly for hunting at night (as well as having keen nightvision). Elephants can hear amazingly low sounds, while a porpoise can hear sounds at higher than twice the frequency of cats! The important thing to know is that sound waves, which are really pressure waves (the compressing and decompressing slinky model we talked about earlier) that push air or water along at a certain frequency, and whether or not we "hear" it as sound when it bangs against our eardrums or resonates within our body cavities is entirely a feature of our evolutionary sensory makeup, not anything to do with the waves themselves.

It so happens that researchers, through EEGs, have monitored the human's brain electrical activity during many different states of awareness and activity, and the frequency of this activity can tell us a lot about our level of alertness or relaxation, which in turn can affect things like mood, creativity, stress, and concentration. These are subsonic frequencies to us; in other words, they are all below the threshold of being perceived as sound, and a good thing too, or our brain would be making noise all the time. Anyway, the frequencies we normally see in the brain can be roughly categorized into four groups:

Beta waves have frequencies from 30-13 Hz, and are associated with alertness, concentration, and high left-brain activity. During a busy workday, if you are actually working, you are probably operating mostly within this level.

Alpha waves (13-8 Hz) are associated with quiet, reflective mental states. When you relax in the tub, zone out watching TV, or read a comforting book, your brain is generally operating in this frequency range.

Theta waves (8-3.5 Hz), are interesting, because they represent the boundary between consciousness and sleep. At this diminished electrical activity, the brain fails to perceive much of its surroundings, and thus is freed to speculate, dream, and have flashes of inspiration. This is that twilight state that's not really asleep and not really awake, or certain times within sleep characterized by rapid eye movement and increased brain function, usually indicating a whole lotta dreaming's going on.

Delta waves (3.5-0.5 Hz) are well below our level of perception but we create them and react to them nonetheless. This is the brainwave signature of deep, dreamless sleep, the lowest metabolic rate, heart rate, body temperature, and blood pressure. In other words, out cold. Interestingly, it is possible to achieve theta and delta wave activity levels while being wide awake; this is one aim of meditation. An experienced meditator can calm her brain down to produce mostly delta wave activity, which gives the subjective state of complete detachment from the outer world, of being in the void. This is very rejuvenating just as it is when the sleeping version occurs, but since the mind is NOT asleep but in a deeply slowed and altered state, interesting visions or insights can occur while in a waking delta or delta/theta state.

To compound all this, it's not only the electrical frequencies our brain generates by itself that tell the entire picture. We're bombarded (usually) by sounds of various frequencies all day long. Some of these happen to fall into the same subsonic categories described above, and when they do, they resonate with the brain's own natural waves and tend to amplify them. In fact, the brain will "entrain" itself to alter its emissions slightly to purposefully resonate with a closely proximal sound frequency if it can, so that amplification (intensifying) rather interference (canceling out) occurs. Here's where things get wild.

You obviously know that music has an emotional and sometimes intellectual effect on you. It can make you cry, experience joy, or feel artistically inspired just by hitting the right notes or chords. A lot of this is due to the words, the talents of the musicians, and so on, but a lot has to do with just basic brainwave activity. Most phenomena like music emit a whole spectra of sound frequencies, but some music in particular, and certainly artificial sounds generated with a synthesizer, generates all or most of its sound in a narrow band, with resonance nodes or "echoes" occurring above and below our range of hearing. You may have heard all the propaganda about babies who listen to Beethoven grow up smarter, or certain types of classical or ambient music/sound being more beneficial to an alert state needed to study, say, while other are prone to put you in a kind of trance, or make you fall asleep altogether. This isn't an accident and it's not pseudoscience: it's the result of sound of a dominant, focused frequency hitting your brain and "entraining" it to enter one of the four states more strongly than before. Strongly enough to affect your subjective conscious or unconscious experience.

Lots of people now think that places like Skara Brae in Scotland, Teotihuacan in Mexico, and the Great Pyramids at Giza acted as made-man resonance chambers that, in addition to meditation and ritualized song or instrumentation played at just the right frequency (one which matched the acoustics of the chamber), could alter the perceptions of a shaman or priest and allow him to have visions, out of body experiences, and even a deep sense of being one with a god or gods. That's why he was the priest, no doubt. It's called "The Perennial Philosophy" and the author Aldous Huxley was famously interested in it. Whether these people consciously understood what they were doing and had some inkling that science rather than mysticism was going on, we can only wonder. Likely it happened from our earliest days spent in cave hollows that resonated particularly well and made people who played the right music or chanted in that room of the cave "feel" a certain way, and this was reproduced when civilizations arose and we began to build our own artificial structures.

I could go on an on about how brainwave activity can induce feelings of flight, of omniscience, and how these feelings may have inspired the art and mythology of entire cultures, and account for the many instances of flying men or gods in ancient lore throughout the world. Maybe that will be the subject of a future piece. For now, I wanted to share with you how sound waves can profoundly affect our brain, and therefore our mind, and therefore our mood, energy level, and our whole subjective experience. Whether we are "in the zone" or feel "out of sorts." Inspired or bored. Hyper or chilled out. There is much more research to be done in this field, but I encourage you to use this as a starting point if you are interested and go out and do more research on your own. Not too long ago (in my own childhood), this was considered maverick science in the West - though on the other side of the iron curtain much more progress was made by Bulgarian scientist Georgi Lozanov and others that has only since the 80s and 90s really come to be known and accepted worldwide. In fact, it's become practically mainstream; you'll find no shortage of books, documentaries, musical/ambient CDs, guided meditations, and university researchers looking for volunteers concerned with the subject.

Just how can we use this phenomenon to our advantage? Can we control our level of brain activity not only by meditation or sleeping but by listening to the right tonal ranges of sound as well? I believe the answer is a strong "yes," and there is now a wealth of science to back that opinion up. We can make ourselves more alert and receptive to learning; we can tone it down and relax, tuning out the world. We can increase our chances of finding creative inspiration, and we can deepen our sleep to feel more refreshed. If we are a bit more adventurous, we can combine states in such a way that we are alert while dreaming, say (lucid dreaming), and use that to further explore states of altered consciousness. It's pretty exciting stuff, so get out there and check it out if that's your bag. I can answer questions you may have if you care to share them in the comments section, though I warn you I'm no expert, just an interested student of the emerging science of consciousness.