Neural Oscillation and Other Curious Frequencies

Sound therapy or sound healing has an extensive history. Ancient Egyptians, Greeks and Mayans among others have used sacred sounds for healing ceremonies and religious occasions. In this article, we will expand on the topic of frequencies and explain what happens in the brain when we listen to sounds.

Neural Oscillation

It was around the 1920s when a German researcher Hans Bergman noticed that neural activity in the brain was rhythmic and investigated this phenomenon using his invention - the electroencephalography device (EEG) that measures electrical activity. Bergman found what we now call “neural oscillation” or in other words, rhythmic vibrations of the neurons in the brain. Not only did Bergman discover that the brain “vibrated” but he also noticed that vibrations changed depending on the mental state. Hence, Bergman distinguished between four brain states or “waves” that he identified and named after the first four letters in the Greek alphabet. - Alpha waves with 7.5 – 12.5 Hz frequency that our brain emits when it is in an awake but relaxed state. - Beta waves with 12.5 - 30 Hz frequency are brain activity when we are awake, but actively engaging our brain with thinking, speaking, reading or writing. - Gamma waves with 25 - 100 Hz frequency are associated with a type of Zen state such as when we are practising meditation. - Delta waves with 0.5 – 4 Hz frequency are the waves associated with a deep sleep state when we are dreaming. Notable scientists after Hans Bergman discovered there were more than these four states, with subtle frequency bands and waveforms adding Mu, Sigma and Theta waves to the mix.

Entrainment and Binaural Beats

The term “entrainment” was first coined by a Dutch physicist Christiaan Huygens in 1665, nearly two centuries before Bergman. It refers to the phenomenon that can be observed when two independent waves with different frequencies can interact with one another if they come in proximity so that after some time of modulation, they will eventually reach an equilibrium state where both frequencies will match. Huygens' discovery sparked great interest because scientists speculated that if brain waves behaved like physical waves, then this principle should explain how the brain manages to modulate sound from the two sound sources, the ears and modulating it into one soundwave in the brain. With Bergen's EEG device researchers were able to test Huygens' hypothesis for the first time and this is how binaural sounds or binaural beats were invented. Binaural music is special in that it must be listened through headphones where different frequency sound is played for each ear. The intended effect is that the two waves will modulate in the brain and make it vibrate at a desired frequency - alpha, beta, gamma or even a custom one. Scientists were convinced that binaural beats had a positive effect on the brain and believed they would be able to use the principle for medicinal and healing purposes.

Sacred Frequencies

With decades of research in sound therapy, physicians have examined the effects that individual musical instruments produced and also were curious to test some of the supposedly “sacred” frequencies. One example of a sacred frequency is called the “fundamental frequency” or simply “fundamental” that represents the lowest frequency in a periodic waveform. If this sounds way too complicated, just try imagining hitting a Tibetan bowl or a Japanese gong because these instruments are based on the fundamental frequency. Another example of a sacred frequency was the original six tone Solfeggio Scale developed by the Italian musician Guido of Arezzo who based the six tones on mathematical principles discovered by Pythagoras in Ancient Greece. Some speculate the Solfeggio scale was based on the Bible's numerology which may or may not be true, but it's a fact that the six tones were used by monks to sing sacred Gregorian Chants. In ancient Vedic and Hindu traditions, mantras and chants have strictly defined frequencies at which they must be pronounced in prayers. Did you know that the frequency of the sacred mantra OM should be precisely 7.83 Hz? Clearly, this frequency has not been chosen at random. For the last thousands of years sound healing practices evolved hand in hand with the advancement in scientific discoveries about the wave nature of sound and the mathematics behind music. If you ever wondered why certain music makes you happy, sad, sleepy or ecstatic, then you should know that the frequencies are to blame. On the other hand, some frequencies if utilised properly can elevate our brains into a higher state of being.