soundcheck with no band, just the room breathing

I'm standing in a venue the size of a cathedral, but there's no band, no crowd, just me and a board with faders that go up to eleven hundred. Every time I touch a fader, the room exhales — not a note, just air moving. I keep trying to find the channel that makes it stop, but it's not on the board, it's behind the back wall, and I know it but I still keep flipping.