You've probably encountered this problem before. The awkward presence of eyes, your eyes, sensory organs constantly feasting on the rich input of the world surrounding.
What do you do? You are listening to a radio play, but your body is primed to engage visually, as it is accustomed. You aren't used to this, this imagery from within. While reading, your eyes are occupied, so busy consuming words that you can forget that they are translating text into narrative. With audio drama, your eyes have nothing to do but look around and try to distract you.
What do you look at?
Close your eyes, and you might fall asleep. Instead you choose to keep them open as the story takes your mind away from the world immediately surrounding you.
You stare at the strange spot on the ceiling, that shouldn't be there, it looks like water damage. Oh dear, it might collapse on your face. Turn away, quickly, don't think about the possibilities of structural failure. Instead, glance at the back of the head of the person in front of you. You are on a bus or train. An elbow jostles you. Now you are seated in a theatre, watching a “live” performance, with a bunch of oddly dressed actors pretending to be from the 1930's for some reason, even though the characters they portray come from different times. Ok forget the back of the head, it's a boring head. You're sitting behind a big beige ball of annoying. What else is around?
Speakers. There might be stereo speakers. You are alone in your room now, listening propped up on pillows, your hi-fi spreading delicious sounds all around like a warm blanket. They speak to you in all sorts of timbres, these voices of gods. Then your room melts away The sounds erode even the harshest imagery. Your eyes begin to forget themselves.
You are on the road, in a van that smells of old cigars, surrounded by traffic. There are cars everywhere, and engine noise and honking horns, angry commuters changing lanes, grimly baking in the Los Angeles sunset. The sun turns to brown, sooty clouds, it pours for weeks, washing the black dust from the cars, the rain patters on the tin roof of the van, and through all of this, you are lost within Gormenghast, or hopping through Planet B. Sherlock Holmes explains himself as you exit the turnpike. A million people on the highway, and only one of them is deep within the sordid lovesong of Alfred J. Hitchcock or being slyly charmed by Winston Hayballs.
Back on the road, now. The announcer lists the credits. Back in your room, now. The file comes to an end, or the tape runs out, or the CD stops. Back in your world, your eyes return to looking outward instead of inward. The actors on stage take their bows next to their steel microphones. The train halts at the final stop. The person in front of you stands up and turns around, flashing a smile. No, wait, that's an icy glare. You were staring at her the entire train ride home.