I have been experiencing ringing in my ears A LOT lately! Its rarely my left ear though. I'm getting both high and low pitch sounds in my right ear. Several days ago I actually posted a thread asking something similar because it was driving me crazy.

That night it was only my right ear but went on for literally hours! It was never like any ringing I had experienced before though. It was going high, low, high, low and it was constant. Towards the end of the probably 5 hours it lasted the low tone was less frequent and the high tone was getting louder and lasting maybe 30 seconds each time while the low tone got to the point it was maybe 5 seconds if that. It finally ended very abruptly.