Ear potential that is transmitted along the spiral ganglion, which sends information through the auditory portion of the vestibulocochlear nerve to the temporal lobe of the brain. The human ear can generally hear sounds with frequencies between 20 Hz and 20 kHz (the audio range). Sounds outside this range are considered infrasound (below 20 Hz) or ultrasound (above 20 kHz) Although hearing requires an intact and functioning auditory portion of the central nervous system as well as a working ear, human deafness (extreme insensitivity to sound) most commonly occurs because of abnormalities of the inner ear, rather than in the nerves
CB usage in the United States types of diathermy machines commonly operate in this range. These devices centered on 27.12 MHz with a tolerance of ±163 kHz, that is, 26.957 to 27.283 MHz. The Business Radio Service has several channels just above the Citizen's Band, at 27.430, 27.450, 27.470, 27.490, 27.510, and 27.530 MHz. The federal government has the frequencies from 27.540 up to 28.000. Many civilian agencies use, or used to use, the frequencies 27.575 and 27.585 for low-power use. These frequencies are often used by illegal operators using modified CB or amateur radio equipment. The 10 meter amateur radio (ham) band runs from 28.000