Reply to Scott K: Like auditory hallucinations, sometimes tinnitus "plays back" some sound you've heard...that day or decades ago. It might be possible that you're "hearing" your old office environment replayed. If I'm exposed to more sound than usual (pretty quiet here), I often "hear" some of that sound during the night. Perhaps it's possible that our ears never just "make up" sound, but always play back something we heard at some point in our lives. Of course, norms can't begin to understand all this!