This is one of my favorite sound design opportunities of all time.  Setting a show in a very dark immersive collapsing mine shaft is a sound designer's dream!  I pulled out all the stops and used 17 independent channels of audio feeding 17 speakers spread throughout the roughly 80 seat black box theater.  Combined with almost pitch dark lighting, we were able to give the effect of a mine collapsing all around the audience.  

The loneliness of the mine was emphasized through the use of body mics carefully hidden on both actors.  At specific points in the show, these were triggered to send a very faint echo of the actors voice through the room, giving the subtle effect of their voices echoing down cavernous tunnels in the distance. 

To complete the immersive experience, the audience entered the house through a back hallway that had been designed to look like a mine entrance.  A hidden speaker supplied that entrance with the above ground soundscape of a working mine that then transitioned seamlessly to the underground sounds as the audience waited for the show to begin.  All of this served to intensify the eventual silent loneliness of the collapsed mine later on.

I’ve attempted to include some mixed down versions of various moments of the show, although there is something lost when going from 17 channels down to 2.