Jingle jingle goes the alternator?

I can't figure out what might be making this noise. It doesn't seem to increase in pitch or volume with higher rpms but the sound is definitely there. All the pulleys look good and the belts are almost brand new with no signs of wear. Sound seems to be coming from the top of the motor as evidenced by hearing the sound through the sunroof when I pass under trees on the road. I'm assuming this sound might be due to the alternator getting ready to go south. Does this sound about right? The only problem I'm having with this is that the sound comes and goes. When I first started the car this afternoon, it was really loud. Drove it 20 miles down the highway and by the time I pulled into the driveway the sound was almost gone.

Everything else on the car looks good and the car runs excellent.

Use a stethescope to pinpoint the sound. I like a piece of garden hose as my stethescope.

I used my mechanic's stethoscope yesterday and the sound seems to be coming from the alternator. Of course, as soon as I bitched about it on the forum the sound pretty much went away. I think it might be a noisy alternator or a sign that it's about to go south. Might be time to hit up Ed for another.