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
Room modes insulation, is very effective, but needs to be very thick (perhaps four to six inches) if the result is not to be a room that sounds unnaturally 'dead' at high frequencies but remains 'boomy' at lower frequencies, so that it provides absorption across a broad range of frequencies. Curtains and carpets are only effective at high frequencies (say 5 kHz and above). As a rule of thumb, sound travels at one foot per millisecond (344 m/s), so the wavelength of notes at 1 kHz is about a foot (344mm), and at 10 kHz about an inch (34mm). Even six inches