I'm very curious about this myself. Tinnitus started for me around twelve years ago. A little louder over the years. I can hear it in both ears, spatially. But more and more so recently, I've been having a sizzling, dissolving noise that occurs, to me, in the frontal lobe, slightly right. That's how I experience it. It's definitely not the noises I hear in either ear. I notice more when going to bed and especially in the morning waking up and laying in bed. I run a fan and generally cover and ignore my tinnitus. But this noise and its location, I cannot do that with. It's a bit concerning because of that. My first hope is like what you're asking, what is it?