A question about Dog's Ear

Burning Wheel First Reading
1

Hi all,
I finally started GMing BWG and I already found something I don’t understand (yay me!).

One of my player’s character has the spell Dog’s Ear (he’s a conman with the Gift and wants to be able to overhear useful conversations).

The manual says the spell’s Ob is “Perception” but… whose Perception? Not the PC’s I assume (or the spell would be more difficult as the stat goes up, which doesn’t make much sense to me). How does it work?

Thanks!

2

The Ob is the Perception of the target of the spell. The idea is that the better your Perception is, the harder it is to enhance.