In reply to aln:
I got it towards the end of last year too! Age 49.
Same reason! Lots of gigs & clubs especially in small venues with incredibly loud bands.
Previously I had it persist for a few days after gigs but it always faded away. Maybe I always assumed that would be the case?
It wasn't bad at all until what I think was a stress induced 'panic attack' early into the first lockdown when suddenly it came to the fore of my attention while sitting at my home work desk. It waivers on a daily basis and on how occupied I am, and is concentrated in my left ear (at least that's my perception of it). Its like the hiss of waves or static mostly and means I need subtitles for the TV most of the time!
Those empty lockdown days were difficult at first. Then I started listening to long play sounds on YouTube, like waves crashing or rain on a tent: really helped me sleep.
Rarely notice it when at the climbing centre or with friends, or out hillwalking (if its windy, all the better!). If I'm camping I will but I bring music with me for those evenings.