According to Dr. Chang, you should not consider getting a hearing aid until your hearing has stabilized. That means no change in your audiogram results year over year (12 months apart). If you get a hearing aid now, you could be chasing a moving target (hearing response changing often), making it difficult to adjust the aid's response properly.
As for what to do now, be as healthy as you possibly can be. Eat a balanced diet. Avoid sugar, caffeine and alcohol. Get plenty of sleep and aerobic exercise. The healthier you are, the faster you will recover and the better the chance the treatment will be successful. Perhaps your tumor may also shrink, although this is relatively uncommon, so you should not expect it.
Taking natural anti-inflammatory supplements (such as the curcumin PaulW suggested) will help lessen any side effects due to the tumor swelling from the radiation treatments. This is not just wacky hippie theory. When I asked Dr. Chang's assistants if there was any problem with my taking natural anti-inflammatories, they told me it was actually a good idea. The most effective anti-inflammatory I found was bromelain (an enzyme contained in pineapple and which some clinical studies have shown shrinks some tumors). I found it helped keep my symptoms manageable. Along with other things I did, I believe it was partly responsible for my tumor shrinking (although I have no way of knowing this for sure). Bromelain must be taken on an empty stomach to be effective.
A few things to consider, in brief:
1. Sleep increases blood flow to the brain, which is necessary for healing and to carry away inflammation.
2. Cane sugar goes straight to any tumors in the body, feeding them. This is why radioactive isotopes are put on sugar cubes for a patient to eat, when doctors seek to find the location of a suspected tumor.
3. Walking helps to retrain the brain's sense of balance, compensating for loss from a damaged vestibular system. The more you walk, especially on uneven ground, the faster your balance will improve (assuming it's not already perfect).
Best wishes,
TW