You really want to know how bad it is?
Go camping somewhere where there is no cell signal AT ALL.
Stay for a week, then come back into cell signal areas again.
Ears ring very loudly, and you can even hear voices and conversations going on.
Granted it's not very distinguishable audio, you can still tell what it is.
I had it happen to me this past July, and for about 3 days I kept hearing voices.