I definetly hear ear tones....

However my experiences with tones have ALWAYS been after a loud concert or when I've been out drinking. Unlike PEtras or yours, Cathryns, my tend to last ALL night or at the very least hours at a time. They are really annoying. I have NEVER had a tone like you described where I have been at work and all of a sudden had one suddenly come on, change pitches, change ears, fade or go up and down.