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
500 kHz emergencies at sea were handled here until December 1999. However, because of the near disappearance of the commercial use of Morse code, the frequency is now rarely used. Emergency traffic on 500 kHz has been almost completely replaced by the Global Maritime Distress Safety System (GMDSS). Beginning in the late 1990s, most nations ended monitoring of transmissions on 500 kHz. The nearby frequencies of 518 kHz and 490 kHz are used for the Navtex component of GMDSS. Proposals to allocate frequencies at or near 500 kHz to amateur radio use resulted in the creation of the 630-meter band. International standards