When NPCs in the party get silenced, they won't say anything when you click on them. Know what I mean? Like when you select Minsc, you'll hear something like "Swords, not words!" or "Minsc and Boo stand ready." But if he's under the effect of Silence, you click him and he's mute.
After all the times I've been silenced, I can't believe I just noticed it. And that is some serious attention to detail.
The Toe