I was just walking around in Balmora, when I heard a voice (whose source I was never able to track) say "Yes, it is hidden away, no one will find it", or something like that and there was a sound like an item being dropped. Is this some obscure quest, or just random conversation and my imagination playing tricks?

Thanks to Chronic Restarting Disorder I have never made it very far in the game. Please don't spoil unless absolutely necessary.

Never happened to me before, and i consider myslf a Morrowind vet, having played the game like half a dozen times.

Exactly where does the voice speak to you ? Could it be from a plugin perhaps ?

I was walking from the Mages Guild to the southern gate. It was just after those stairs down on the left.

As for plugins, I only have Better Bodies and the World of Faces. And both official expansions.

Sometimes the locals will have a get together in the river and banter a bit. That sounds a bit far away to be hearing them though, so perhaps it was someone on one of the rooves. Either way, there are no quests that i know of that don't start with a dialogue box or a pop-up log book notification. Certainly none with the mods that you're running.