The study I mentioned in my previous post states that excess red blood cells in PV can result in stalled cerebral capillarly blood flow.

Ringing in ears (Tinnitus) is commonly described as an MPN symptom. This is from the Discussion section of a published 2014 study that showed platelet aggregates cause stalled cerebral capillary blood flow in mouse models of ET. "Finally, in a prospective study of ET patients, neurological symptoms including blurry vision, headache, tinnitus and dizziness were reported. Therapies that decrease capillary stalling could play an important role in reducing microvascular thrombotic and vasomotor complications of the MPNs, including not only neurological disorders but also others such as erythromelalgia, which is caused by capillary occlusions in the extremities."

Ringing in the ear is for sure a rather common symptom in MPNs. One hopes specialist doctors know this.
One hypothesis for tinnitus, over and above hyperviscosity, is the formation of microthrombi due to platelets in ET being hypersensitive. PubMed is a good source for finding studies.

"ET may also cause hearing problems, such as tinnitus (ringing in the ears). These symptoms are believed to be associated with hyperviscosity — thicker, stickier blood — that also contributes to clotting problems."
https://www.mympnteam.com/resources/symptoms-of...
For some people, tinnitus is the only disturbing symptom they have that leads to a diagnosis of MPN:
https://doi.org/10.3889/oamjms.2020.4688
https://entokey.com/pulsatile-tinnitus-as-a-fir...

Pulsatile tinnitus as a first symptom of essential thrombocythemia

https://entokey.com/pulsatile-tinnitus-as-a-first-symptom-of-essential-thrombocythemia/

Symptoms of Myeloproliferative Neoplasms (MPNs) | myMPNteam

https://www.mympnteam.com/resources/symptoms-of-myeloproliferative-neoplasms-mpns

Polycythemia Vera Presenting as Tinnitus and Hearing Loss: A Case Report | Open Access Macedonian Journal of Medical Sciences Open Access Macedonian Journal of Medical Sciences (OAMJMS).

https://doi.org/10.3889/oamjms.2020.4688

I've got big time ringing too, but some of it is from all the loud music over the years. Having ET has definitely made it worse. Over the years I have gotten used to it and I'm able to put it out of my mind for the most part. Sometimes one ear will actually lose a large percentage of hearing and then it comes back. Get used to it cause it'll be with you the rest of your life most likely.

Hi Deepak,
I am new to all of this, recently diagnosed with PV. I have tinnitus as a symptom. I believe it's a known symptom of PV but I don't know the exact cause. I plan to ask at my Drs appt next week. Good luck with everything.