Identify what the narrator directly observes and what is an interpretation. A first-person account may be informative while still limited to one observer's position and knowledge.
Worked example
I could not hear the announcement reports the narrator's experience; it does not prove that nobody heard it.
Original fiction: The Rehearsal Door
From the corridor, I heard a burst of laughter inside the rehearsal room. The door was closed. A minute later, Leah came out carrying a folded script and smiling. I guessed that someone had told a joke. Later Leah explained that a harmless prop had rolled across the floor at the wrong moment. My sound-based guess had not identified the actual event.