I know I can make it instantly worse by clenching my jaw, so that should have been a hint already.
There are some physical therapists (also dentists) that focus on maxillofacial dysfunction and TMJ disorders, so that's an avenue to go down as well.
The other two common reasons for tinnitus:
* Hearing damage (gunshots, explosions, etc.) and those are not reversible as of yet
* Ototoxic drugs. When I last did research on it it years ago, like hearing damage from gunshots, was also irreversible.
There is a well known phenomenon among people with (at least some types of) tinnitus that moving the jaw forward increases the sound, but that this also makes the tinnitus go away for a bit. The way my ENT explained it, it has to do with how your brain calibrates sound. Pushing the jaw forward makes the sound louder, which also causes your brain to adjust your hearing to be less sensitive. Or something like this.
With some types of tinnitus, there is a specific connection to the temporomandibular joint. My understanding is that the causes tinnitus are poorly understood, however. There are many hypotheses, but little solid evidence.
I've had like 2/10 tinnitus for all my life, can't remember the last time I heard "silence".
Got a C5/C6 hernia a year ago, about 6 months after that MASSIVE tinnitus in my right ear and clear increase in the left. Like "can't hear shit" levels of noise.
Eventually I figured out that doing a basic shoulder workout + going on a walk eased it off in a few hours. A month ago, due to a doctor's suggestion, I discovered that taking muscle relaxants just before going to sleep a bit, I've woken up with maybe 3-4/10 tinnitus a few times.
Definitely a neck thing.
1. Laterally sheared and rotated vertebrae in my neck that were causing compression and tension on nerves in my neck
2. Elevated first rib, which was also compressing and tensioning the nerves.
I was incredibly skeptical that PT would fix it even though I was sure it was related to my neck/shoulder. After a few sessions of working to push my first rib back down to where it was supposed to be and also press (quite hard) on my neck vertebrae to move them back into a normal position, the tinnitus went from a 5/10 to a 2/10.
The problem I had was getting the rib and vertebrae to stay put. They would, as a result of lifting things or sleeping funny, slowly start to revert to their original positions causing the tinnitus to get louder again. The PT gave me several exercises to help strengthen muscles to keep everything in place.
After about 9 days one morning the right ear completely resolved and the left ear was at about a 5/10.
Very, very, very long story short, I did a ton of digging and experimenting and realized it was related to a neck injury (a lot of people with whiplash have short-long term tinnitus). Over a year of physical therapy later, the tinnitus in the left ear is usually gone and only flares up if I lift weights with poor form.
If you've had a neck/shoulder injury in the past 1-2 years, it's something I'd look into.