I have this also in the left ear for about a year or so. I self-diagnosed it as eustachian tube related [0] and should really see a doctor, but I also got pretty used to it by now. Only now and then it gets a bit annoying when the sound become more 'whooshing' than 'a clock ticking in the room'.

In my right ear I have another sound regularly, that I went to the doctor for, and she immediately said "Oh, tinnitus, nothing you can do". But I'm pretty sure it is something else. It feels like spasmic tiny muscle fluctuating against my eardrum, and gets triggered by a low-frequency sound, esp. when at rest. Stops after 15-30 mins.

[0] https://en.wikipedia.org/wiki/Patulous_Eustachian_tube

Wait... This is not "normal"? I thought everyone has that...

This is the first time I heard that this is an issue where the brain isn't filtering out noise properly. This explains why I have had tinnitus, the sound of breathing, whooshing in the ears from my heartbeat, etc. audible to me for as long as I've been conscious and have never understood why everyone else seemed to be really disturbed by what I consider to be supremely normal. Except I also have a sensory processing disorder that makes my brain unable to filter input well so I also come off as sensitive to touch and able to pick up smells well. Because I grew up with all this though I have normalized it enough to function.