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
Radio-controlled aircraft the 1983 FCC reform that introduced "narrowband" RC frequencies - at 40 kHz separation from 1983-1991, and finally at 20 kHz separation from 1991 onwards, to the present day with fifty frequencies on 72 MHz solely for flying models. The 75 MHz band became usable only for ground-based RC modeling (cars, boats, etc.) in the same timeframe, with the transition also occurring through to 1991, having 30 frequencies available at the same 20 kHz channel separation. Canadian modelers today flying on VHF-band RC gear use the same 72 and 75 MHz frequencies as American hobbyists do, for the same types