Baldur's Gate : The Sword Coast Chronicles : NWN2 Persistent World

If you detect a sneaker through a listen check you can target him but he will get the sneak attacks on you and you're considered flat footed, if you detect him with spot you are not sneak attacked (unless you don't engage).

all you gotta do is throw a grenade at the ground or an aoe effect, so i guess it doesn't make that much of a difference