Greetings!
Im no doctor, but I got a tiny bit of personal experience.. My advice is that you try out the easy parts in the preavious posts before you do any of the more extreme things. Clearing out excessive wax and such is a good idea. Then simply:
Plug your ears in the morning of your next test-day. Silence and reduction in sounds around you will sharpen your hearing a lot! I used this trick in my military days due to all the noise and sounds around me..and it worked! Just remember to remove the plugs before you put on the audiometric headphones.
Best of Luck,
TJB