Did you get an extended audiogram? That could potentially reveal damage that wouldn't show up on a standard audiogram.
Tinnitus Talk Support Forum
How did he determine you have ETD? I don't think a tympanometry test alone is sufficient. Sometimes the ear pressure is off due to other reasons such as air flight, etc.
I think it was just a standard audiogram. What is an extended audiogram test - do I just ask for one? I have a second opinion in a week's time, so I could ask them.