ALL EARS
'(<a href="http://www.j-archive.com/media/2011-04-29_DJ_18.wmv">Kelly of the Clue Crew shows an anatomical animation on the monitor.</a>)  When you come down from high elevations, the air pressure outside your ear can be greater than inside; swallowing can push air from the nasal cavity through this tube into the ear, causing a popping sound'
the eustachian tube