Charlotte King is best known for her accurate prediction of the major eruption of Washington's Mt. St. Helens, May 18, 1980. She was a mere 12 minutes off. This prediction threw her into the limelight and attracted the attention of scientists and journalists alike, names like Human Seismograph and Incredible Ears soon found their way into print and soon she was seen on network and independent television shows.
Doctors as well as the military were perplexed by her unusual ability to hear sounds in the ULF, VLF, and ELF ranges. She began hearing these sounds in mid-May 1976. Charlotte was tested in four states by the scientific and medical communities, and the tests revealed that she could hear in the under 10hz range. Further tests revealed specifically below 2-7hz. Thus was born what the doctors and the scientists who tested her coined "The Charlotte King Effect."