The Sound of a bad alternator
 

Numerous threads on this topic. Few sound clips or videos. So thought I would post mine. Engine is 1989 3.2 . The sound is quite horrible but does disappear with higher revs. Thought is was chain noise on the left side, so checked that and even replaced the tensioner (had an extra). No change. Then pulled the fan belt : Voila.

https://youtu.be/kboKTcM3KH4

Mine was dead silent. The battery light would occasionally show a faint flicker at idle. When I smelled sulfur from overcharging was when I knew it was time to replace it.

Sounds like the bearings are worn and the fan is occasionally dragging on the housing. The bearings are cheap and replaceable. Or you can wait like I did and replace the whole alternator in the parking lot of a motel.

Yes. However, I didn't find any play at all in the bearings. Everything looks fine. I suspect it's the alternator it self unfortunately.

That's the voltage regulator going kaput