Well my best guess it's fear as in the spell, so that Bay SA seems a good fit. Still, it seems rather potent for a 4HD creature, so I would fancy making it HD dependent.
Frightful Groans (Su): Lost souls constantly emit terrifying moans and shrieks, all living creatures within a 300-foot spread must succeed on a DC X Will save or be affected for 2d4 rounds. Affected creatures are shaken if they have at least as many HD as the lost soul, frightened if they have fewer HD than the lost soul, but at least half the lost soul's HD; or panicked if the lost soul has more than twice their HD (e.g. a 6HD lost soul will panic 1-2 HD creatures, frighten 3-5 HD creatures and shaken 6+ HD creatures). This is a sonic mind-affecting fear effect. Whether or not the save is successful, an affected creature is immune to the same soul's frightful groans for 24 hours. The save DC is Charisma-based.