The middle ear sits between your ear-drum and the ear's specialized sensor organs and balance organs. It is sealed at the ear-drum and where it links to the sensor organs but has a floppy tube connecting it to the back of the nasal passages. This tube is called the Eustachian tube.

When you move up and down in altitude the pressure changes result in a differential pressure between the middle ear cavity and the outside air. This results in a full feeling in the ear, sort of cotton-woolly, and some reduction in hearing capacity. When this pressure difference reaches a certain level air often vents through the Eustachian tube and the pressures equalize. As the pressures equalize the ear-drum moves quickly back to its normal position - the 'pop' that you hear as your ears pop. Sometimes, especially if there is fluid in the middle ear or the Eustachian tube, there is more of a 'crackle' or a 'squelch' than a pop (Sounds a bit like a Rice Bubbles commercial doesn't it?)

When the Eustachian tube is blocked the differences in air pressure can't equalize and the ear-drum can be stretched beyond it's limits and bleed or rupture. The Eustachian tube can become blocked when you have a cold or when you have hay fever type allergies. These conditions cause the blockage because the skin at the opening of the Eustachian tube swells up and squeezes the opening shut.

Most people can deliberately pop their ears during flight or when stationary at a fixed altitude. It's not difficult to do. You can often pop your ears just by wiggling your jaw or moving it with a chewing action. Then there's the Valsalva manoeuvre where you force air up into your Eustachian tubes by blocking your nose, closing your mouth and blowing to gently increase the pressure in your mouth, nose and throat. The Frenzel, or jaw thrust, manoeuvre is where you slide your lower jaw forward to open the entrance to the Eustachian tubes.

Sometime, especially in some sensitive people, when you pop your ears the sudden change in pressure is transmitted, as a miniature shock wave, into the inner ear's balance sensors. This pressure wave confuses the balance sensors which send tumbling or spinning signals to the brain. The brain receives these signals and immediately sets the eyes moving to allow for the perceived tumble or spin. This phenomenon is called alternobaric vertigo which translates roughly as ' dizziness from pressure change'.

Your first step is to learn to let your middle ear pressures equalize without sending a pressure wave up to those balance organs. The best way to do this is to not use the Valsalva manoeuvre but to try, whenever appropriate, to use either the Frenzel manoeuvre or chewing or waggling your jaw to assist in popping your ears. This may take a little practice but after a while it will come quite naturally.