"Ergo draco maledicte
et omnis legio diabolica
adjuramus te.
Cessa decipere humanas creaturas,
eisque aeternae Perditionis venenum propinare."

Sam wasn't shouting, but he wasn't keeping his voice down, either. This wasn't being done in secret, after all, and he didn't need to do so. Besides, more volume could only make it harder on the demon soul.

He also wasn't hiding. Definitely could have been making a target of himself.