Update - June 2022, my tinnitus has lessened. Most days I do not notice it.

I had been looking for possible sources of blood pressure in or on the Cochlea that might explain why Valsalva improves my high frequency hearing so much.

Briefly, I have to reread the information I posted here, but my hearing ends around 4600 Hz and extended briefly to 7200 Hz with Valsalva. One example of hearing is of a mail box alarm (Hanna, sensor in mailbox sends radio signal to an alarm in my house.) When it sounds, about 15 feet away, it produces a sound that I often miss at first. Valsalva transforms that sound from low to loud. Why?

To me, this observation indicates that my diagnosis of "nerve damage" does not account for my high frequency hearing loss. [High frequency hearing loss is very common among older people.] (I'm 79).

1) This briefly discusses the Kim & Lee publication.
https://dizziness-and-balance.com/anatomy/ear/vascular.html
2) This publication has some information on the arteries within the ear and Cochlea.
Kim, J. S. and H. Lee (2009). "Inner ear dysfunction due to vertebrobasilar ischemic stroke." Semin Neurol 29(5): 534-540
https://www.researchgate.net/profile/Ji-Kim-4/publication/38016105_Inner_Ear_Dysfunction_Due_to_Vertebrobasilar_Ischemic_Stroke/links/00b4952d3fc25114a8000000/Inner-Ear-Dysfunction-Due-to-Vertebrobasilar-Ischemic-Stroke.pdf
I'd like to find ear & hearing researchers with interests in this subject.