Sounds of Silence
The human ear can only hear a limited part of the sound spectrum. Above that range is ultrasound and below it is infrasound. Although largely unheard, vibrations in these ranges can still affect the human body in ways that are quite different from the informational aspect of simply listening. These higher and lower registers of sound frequencies are, today, the stuff of imaginative speculation. While the conspiracy watchers believe they are the basis of secret weapons research for covert operations, mind control and other conspiratorial uses, another, more idealistic, school associates them with meditative states and magical technology.
Sound is a waveform, with low infrasonic frequencies having a long wavelength that can cover great distances, and with high ultrasonic frequencies having a short wave length. The medical profession, chiefly for diagnostic imaging, employs ultrasound most usefully. Both ultrasound and infrasound are inaudible to humans but can, on occasion, be f... more
Dina Jacobsen