Thanks nightflyr. When I get home tonight or sometime tomorrow I’ll see what belt(s) I can remove. Elsewhere someone suggested removing the serpentine belt and starting it up briefly to see if the sound persists. I honestly don’t remember seeing any other belts, so I guess I’ll only be able to determine if it’s something driven by the serpentine or not.
The unusual shifting nature of the sound is what really has me baffled. I sure wish someone could explain that to me.