Mine is overall constant, but also variable, consisting of multiple high-pitched frequencies with one frequency or another becoming louder and standing out among the rest, then it fades back and another one increases in volume, only to again recede and another becomes dominant. It's really hard to determine just how many frequencies I'm hearing; seems like three or four, and they cycle in volume randomly. Different in each ear. Lot of dissonance with competing frequencies going on at times. It would be annoying, but it's been going on for so long (1972 or thereabouts) that I almost don't even notice it anymore, like people who have pendulum clocks in their house just stop hearing the constant "tick-tock-tick-tock."