I agree with ya. I can hear it whenever I intentionally seek it out, even when it's relatively loud out there. I tend to think of it as some baseline intensity (at some extremely high frequency/frequensies I've tried but yet to pin down) my brain perceives, that gets washed out more as external stimuli become stronger. This is partly what prompted me to speak about a reference level of intensity distribution over frequency (and therefore a power spectrum if you will) in the other comment thread. Normal brains have a reference level that adapts to the environmental average. Those of us with tinnitus have some nasty spikes at high frequensies. "Hearing silence", I speculate, is more of a response to a changing reference level -- some of the responses will be the brain compensating for the change and thereby inducing acoustic (?) illusions reported in this work. A tinnitus brain will respond to a receding reference level by focusing again on those nasty frequency spikes.