Hey I have an o3 also and the noise is just like you said. It did not start sounding like that until about six months ago. About 40 it chimes in real good. I haven't had it checked yet but I was kinda thinking wheel bearing. Did you get it figured out yet? Also my service engine soon light came on I took it to a mechanic which pulled the code. He took off the gas cap, worked the big O ring off turned it over and haven't had any problem since. The book says check fuel cap and the light will go out but check that O ring. Let me know about the noise what you find out.
Railroadman