The term you want is (Veteran) Service Officer, VSO, typically just service officer. Your state should have an organization of them. The seem to be from American Legion, VFW, or similar organizations. Mine was from VFW.
Get help from an accredited representative
I used one from the VFW. He did an interview, told me what documents I needed to collect prior to our meeting, and then filled out everything I needed. All I needed to do was make it to the appointment.
File for the disability. A clock starts when you file. If your claim is approved, you get back pay back to the point you put in your claim. You will have an appointment/exam (compensation & pension (C&P) exam) to measure your loss. Generally your hearing has to be bad to get a hearing loss disability. If tinnitus bothers you, that is a separate loss and is based on your description of how much it bothers you, not on any tests. I was able to receive 10% for the tinnitus, but my hearing loss only crosses into moderate, so I don’t get any disability for that. (0% - if it gets worse later I can re-apply.)
Hope this helps! Thanks for your service!
WH