It sounds like you very well could have noise damage but one thing I have noticed is a tendency for ENTs (and people on this forum sometimes) to automatically assume noise induced tinnitus.Isn't hard mewing forcefully applying pressure? Soft mewing is simply resting the tongue on the top of the palette, which is what I was doing. Also, I can't afford to get an MRI with my hyperacusis. CT scan and x-rays are fine though. I happened to be blasting my headphones and mowing lawns without hearing protection around the time I got tinnitus/hyperacusis. Anyway if it's some obscure nerve being touched due to mewing then I guess we are fucked lmao, I don't have the money to go through extensive testing.
To complicate it, some non primary noise causes are actually acutely triggered by noise (e.g.. Third window syndromes like perilymph fistulas or secondary hydrops which can be noise triggered) but treated very differently.
And there are people with noise induced hearing damage that can have other co-morbidities like TMJ or vascular issues that have an additive effect and make tinnitus much worse. Some people could have more mild tinnitus by dealing with these cofactors.
When someone gets tinnitus and doesn't know why, the first thing people ask is have you ever been to concerts or used headphones and almost *everyone* has.
Tl;dr: Yours could primarily be noise induced but, if possible, it's always a good idea to rule out as many factors as you can, as long as the test (e.g MRI) isn't risky itself.