pf2e.fyi
From Pathfinder Adventure Path: Gatewalkers, which isn't enabled.

Shroud of Silence

HAZARD 4
ENVIRONMENTALMAGICAL
Stealth +15 (expert)
Description Sounds become muted in a 20-foot-wide, 100-foot-long segment of this street corridor.
Disable DC 25 Occultism (expert) to twist the magic of the ley line around you, disabling the hazard for only you; or Dispel Magic (4th rank; counteract DC 23) to disable the hazard permanently
Hush (illusion, occult)
Trigger A creature reaches the street's halfway point
Effect Each creature in the affected area must succeed at a DC 23 Will saving throw or be silenced as long as it remains in the area. A silenced creature makes no sound and can't use abilities with the sonic or auditory traits, including casting spells that don't have the subtle trait.
Pathfinder Adventure Path: GatewalkersORC