Hearing occurs when sound waves strike the eardrum, sending vibrations through a set of tiny bones leading to the inner ear. There the sound is transformed into nerve impulses that then travel to the brain. The ear boasts two main passageways, one visible, the other hidden. Riding atop the inner ear are the semicircular canals, which help us maintain our balance. To maintain health, air in the middle ear must be at the same atmospheric pressure as that outside the ear.
Air reaches the middle ear via the eustachian tube, which is connected to the back of the nose.
Air passes through this tube to equalize pressure 1,000 times a day. The nose is the main entry point of air for the lungs. Inhaled air is cleansed, moisturized, and warmed by the cilia and mucus that line the nasal passages. In addition, when cilia are touched by air, they send nerve impulses to the olfactory areas of the brain, which register our sense of smell. A Close Look at the Throat Return to top The throat consists of the pharynx, epiglottis, and larynx.