Hearing auto-attacks and spell casts in the fog of war

I wish I could have captured this (I couldn't), but it was happening for a bit of the game I just played.

The enemy Kalista was taking everything in her bot side jungle, and we had no vision there. However, I could hear her auto attacking and rending at the different camps and could call out where she was in the jungle in all chat. When I did call it out, the enemy Kayle admitted that she could hear me taking their blue buff (which was also in the fog of war) multiple times throughout the game, which is also how she caught me out once. Kalista also responded that our Malzahar's voidlings were making noise in the jungle, once again, out of vision. To all of us, however, we didn't see any particle or visual effects coming from the fog of war. Maybe it was a glitch with ghost poros or something.