Even if a character is not trained in Spellcraft, Prot. Evil, as mentioned already, has an obvious magical effect. Likely some sort of bubble. And, it may also depend on how the DM views magic. In a lot of fantasy, if a caster's spell is disrupted or terminated by external means, they feel it physically, even if they're blinded and deafened. Sometimes, the disruption can even cause internal hemorrhaging or death, especially if the caster of the disrupting spell is much stronger than the one who cast the spell being disrupted.