You can move machines, operate computers and control other people with your mind. This may sound like an SF film, but scientists are developing technologies that enable the handicapped to move things and their body with the power of thought. Such technologies revolve around controlling brainwaves.
There is an ambitious plan to exploit brainwaves. The Defense Advanced Research Projects Agency (DARPA) is working on Silent Talk, a project dedicated to brainwave-based telepathic communication. When a person tries to say something, a certain pattern of brainwaves is first formed before neural signals are sent to the vocal cords. Once the pattern of brainwaves is analyzed, we can understand what the person was trying to say. Silent Talk is designed to develop a device that enables telepathic user-to-user communication without the use of vocalized speech.
Such a technology has distinctly sci-fi overtones. However, things that were only possible in sci-fi movies are becoming a reality. So, high hopes have been pinned on the future of brain sciences.
The human voice, sound waves and the voices of the brain :brainwaves
The human voice produces sound waves
Sound waves reverberate as the differences in air pressure make the air particles move from compressions (regions of high air pressure) to rarefactions (regions of low air pressure). Such pressure fluctuations cause our eardrums to vibrate. The standard range of audible frequencies is approximately 20 to 20,000 Hz. The frequency range below 20 Hz is called ultra-low-frequency sound waves (or infrasound) while that over 20,000 Hz is called ultra-high-frequency sound waves (or ultrasonic waves), which are used in developing various medical devices and health-related products.
The voice of the brain: brainwaves
Due to the electrical flows created by the delivery of signals between cerebral nerves in the brain, the electrical activity of the brain is constantly measured in a test called an electroencephalogram (EEG). Brainwaves have a frequency bandwidth of 0.2~50 Hz and an amplitude range of approximately 10~200uV. Brainwaves are divided into five categories depending on the frequency, amplitude and voltage gap.
Alpha (α) waves (8-13 Hz, 20~60 uV) reflects a wakeful, relaxed state that is characterized by a effortless alertness. They are also found when people concentrate on studies, meditate or ponder over something with closed eyes.
Beta (β) waves (13-30 Hz, 2~20uV) indicate an aroused, mentally alert state. They are related to our five senses. The fast Gamma (γ) frequencies (30~50 Hz, 2~20 uV) correlate with high energy states and excitement.
Delta (δ) waves (0.5-4 Hz, 20~200 uV) are dominant in a deep sleep or a coma. Delta (δ) waves are also related to the production of large amounts of growth hormones. But they also appear when the person has a brain tumour or encephalitis.
Lastly, theta (θ) waves (4-8 Hz, 20~100 uV) reflects a trans-like state between conscious awareness and dreams. They appear when people have fun or doze off. They are said to determine creativity, the power of memory, supernatural power, concentration and learning ability.