when you have multiple things that can be percieved... do you roll a perception for each one?
scenario: the enemy is in a room some distance down a hallway but and has rigged a simple trap to trigger an alarm when anyone reaches a point in the hallway.
If the party has not already told me something like "we walk carefully down the hallway checking for traps and listning for voices" I plan to give them a perception roll when they reach the trip wire.
my problem is that when they roll should they roll 2 perceptions (one to hear the voices of the enemy down the hall and the other to notice the trip wire
or should they simply roll one perception give them all the information for the DCs they surpassed.