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Chapter I: What is a Tone?

Simply stated, tones are quite literally vibrations. Any object of mass has its inherent fundamental frequency, or a tendency to vibrate in a very particular way. From the string of a guitar in tension, to a building, to the planet we live on, to the people that live on it! Why then, do we not hear bridges sing and the earth whistle? This is because not all vibrations are hearable through our ears.

Human hearing allows us to pick up only a narrow band of the spectral stretch of possible vibrations, roughly those vibrations with frequencies between 20 and 20 thousand cycles per second. Now it is time to clarify some physical concepts:

> Sound as we hear it, is generated by a vibrating body of mass, which pushes and sucks back pockets of air cyclically from its immediate environment. (This is why there is no sound in a vacuum).

> Sound then “travels”, as this difference in air pressure propagates through the environment in all directions.

> Our ears have tiny little hairs that sense these subtle changes in air pressure. Our brain decodes this information as sound.

> The magnitude and polarity of the pressure in the medium (air, water or other) oscillate regularly due to the vibration of the source and so this process can be thought of as a propagating wave.

> A wave can be mathematically modeled with two basic parameters: the length of a whole repeating cycle (wavelength), and its magnitude or volume.

> All sound waves propagate through air at a constant speed. Knowing this and the wavelength we can say how many such cycles are repeated per unit of time. This we call the frequency of a wave, and it is usually expressed in cycles per second, or Hertz.

The frequency of any given tone determines what our brain understands as “pitch”: the higher the frequency, the higher the perceived pitch of that tone. We can hear very low-frequency tones, such as the roar of a lion. But below that there are tones so low, that we can’t pick them up with our ears, such as some sounds emitted by whales. An even more extreme example would be the rotation cycles of our planet. We also can’t hear those, but the planet is sure moving with a constant frequency! Figuratively speaking, maybe God has big enough ears, that He can actually hear the Harmonice Mundi, or the harmonies of the planets, as proposed for the first time by Pythagoras, and later elaborated on by the 17th century German astronomer and mystic Johannes Kepler.

On the higher-end of the spectrum, we can hear very high tones, such as flying bugs or tinkling keys. But beyond that, our ears won’t be able to register them. For example, we can’t hear some sounds made by bats, or those specially produced dog whistles, which create tones that only our hairy friends can hear.

So whales produce sounds under 20 Hertz, and bats can squeak tones well over 20 kilo Hertz, neither of which we can hear. But then an intuitive question arises:  could we somehow sense these extra sonar vibrations with other organs, and maybe even unconsciously? Sure we can! We perceive higher vibrations as light, through our eyes. Vibrations in this registry take the form of colors when decoded by our brain. Furthermore, we perceive infra-sonic sounds as pressure in our chests; remember that concert, where you stood real close to the speakers?

And unconsciously we could be picking up all kinds of vibrations, high and low. Could other kind of information be coded into and transmitted through ultra sensorial vibration? This possibility gave rise to a large number of commonly occurring extra sensorial experiences being interpreted by people, such as a person giving you “a bad vibe” or a place having a very harmonious atmosphere.

Let us for now go back to the measurable frequency range. Research in the field of brainwaves has successfully linked the different ranges of brainwave activity (Beta, Alpha, Theta and Delta) with associated states of consciousness. Even the current Dalai Lama has been the subject of brainwave analysis by western scientists, who want to explore the rhythms of the brain during states of deep meditation. As we begin to see, there is definitely much more to sound and vibrations than that, which we are used to experience!

As we learn more about the nature of sound, some important aspects of tones must be introduced and explained.

Tones are known to interact with one another and with other vibratory bodies they come in contact with in very interesting ways. For example, two tones can interfere constructively (amplifying the sound), or destructively (cancelling the sound altogether), depending on the phase difference between them.  A partial cancellation of tones that are slightly different in frequency can lead to an emerging third vibration or beat, known as a Binaural Beat.  A structure, which is flexible to vibrate at more than one rigid frequency, will have the tendency to synchronize its movement to the influence of a dominant vibration.  Being our brain (and for that matter, our whole being) exactly that, namely a structure with varying ranges of vibration, it starts to become apparent, how sound and vibration could influence our state of mind and through it, perhaps even our consciousness, our health and our general well-being.

Another very intriguing characteristic of tones and vibration in general, is the presence of so called Overtones or Harmonics. A single vibratory source has, given the right conditions, the capacity to produce not only its fundamental tone, but also other subtler versions of itself and manifest a series of many different sounds ringing at the same time! More about Harmonics and Overtones is presented in the next chapter.


 Read More: What are Harmonics and Overtones?

Audio Samples: Hearable Frequency Range

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