All very interesting!
Perhaps I may be of some help to you guys.
The ear is divided into 3 parts:
Outer ear = ear canal and ear drum.
Middle ear = air filled cavity behind the ear drum.
Inner ear = even deeper behind the middle ear where all the nerves are and nerve impulses leave to go to the brain.
The middle ear is as I said an air filled cavity. Air in this cavity is supposed to be at an equal pressure to the air outside the ear. This is maintained by a small tube which leaves the bottom of the middle ear and opens at the top of your nasal/throat area. This auditory tube has a small muscle at its base which opens the tube and allows the pressure in the middle ear to equalise with the pressure outside. This can be induced by yawning, swollowing etc.
Equalising pressure in this way is normal whether you find it hard or easy to do.
Some times the tube gets blocked and leads to a build up of fluid from the walls of the middle ear. This can take time to drain once the cause of the blockage has gone and may be heard as a popping sound. In children this is more common due to their anatomical proportions but less common in adults.
Grommets are small plastic circles with a hole through the middle, like a Polo mint. Inserted into you ear drum they are useful if your ear is finding it very difficult to drain on its own.
A small hole in your ear drum (Tympanic Membrain) caused by diving should heal on its own in about 3 months. If you have a hole like this you will not hear so well and if it doesn't heal the you may need a small Op to cover the area.
On the subject of damage due to pressure changes I think the jury is still out. I see plenty of divers and pilots with hearing impairments, however, it's impossible to say whether in a pilots case the cause is more noise related pressure related or both.
Hope this is of some use to you even if a little long winded.
Aiki.
[This message has been edited by Aikipilot (edited 22 August 2000).]