In 1954 Schumann and König reported on their discovery of naturally occurring electromagnetic pulsations on the Earth. Schumann resonances are natural waves excited by lightning strikes in the cavity between the Earth's surface and the ionosphere. In essence, lightning pumps energy into the earth-atmospher cavity, and causes it to vibrate or resonate at extremely low frequencies. The electromagnetic waves created by lightning travel around the Earth at the speed of light, reflecting from the ionosphere to earth and back again in cyclical fashion. These waves circumnavigate the globe an average of 7.83 times per second. As noted above, this frequency correlates with the average frequency of alpha brain waves in human beings.
There is an enormous range of electromagnetic frequencies either already in use or suggested for use in health care. Most of these frequencies deliver signal shapes of the simple sine wave variety. The frequencies in use range from the extremely low frequency (ELF) range of 3 to 300 Hz to the upper end as high as 50 billion Hz (50 GHz). For wellness and safety for the use of devices at home, it is recommended to stay with a device that delivers electromagnetic pulsations in the ELF range.
The basic frequency (and highest intensity) mode of Schumann resonance, or the "tonic frequency," is 7.83 Hz. An overtone is a natural resonance or vibration frequency of a system. Those who sing or play guitar are familiar with the creation of overtones – frequencies of sound that are often created by superimposing one fundamental frequency upon another. Further resonance modes occur at 6.5 Hz intervals due to the Earth's spherical geometry. These resonance modes (overtones) are detected in the background radio noise of the Earth's energetic field as separate peaks around 14.3, 20.8, 27.3 and 33.8 Hz. Furthermore, these overtones seem to be essential for our bodies.
If our bodies are blocked from natural exposure to these natural waves (e.g., due to living and working in buildings constructed with concrete, steel and metal alloys, driving in cars on paved roads, and by the electro-pollution of ultra-high frequency radiations from cell phones, microwave ovens, wireless phone and computer networks, and radar/satellite signals, etc.) we are more susceptible to illness, loss of cell membrane integrity, compromised immunity, and depression. Recorded dips in the Earth's Schumann resonances have had strong correlation to heart attacks, car accidents, and in a general increase in the death rate. (Beck 1992)