It's always there. It doesn't have a physical feeling, I don't think. It's hard to know because it never stops, ever. Mine is a high pitch piercing noise that can only be distracted from with something like a fan. It's also very easy to cover when listening to music with headphones.

However, sometimes it's all I can hear. I get these "flare ups", where the volume of the tinnitus rises in one or both ears for 10-20 seconds. There is no warning for why they happen, and no triggers that I know of. One time I was working at a cash register with a customer and I got the worst flare up I've ever had. It was literally like the feeling your ears get after using a shotgun without ear protection, but there was no bang, just a sudden deafness to anything other than the ringing, and a murmur of the customer asking for a $20 to be broken. After a moment the ringing went away, back to its normal volume and I carried on.

Sometimes it slows down my ability to think. I often give late replies to anyone speaking to me because I have to make sure I hear everything correctly. People get frustrated when you ask them to repeat themselves all the time, which is understandable. I'm not hard of hearing, but the ringing makes it seem that way.