Down the tunnel Hackworth walked, following the woman, and as he went the 
light grew dimmer and the tunnel narrower. He suspected that the walls of the 
tunnel had mediatronic properties because he kept seeing things from the 
corners of his eyes that were no longer there when he snapped his head around. 
He'd assumed that he would soon reach a chamber, a swelling in the tunnel where 
this woman's friends would sit pounding on enormous kettledrums, but before 
reaching any such thing, he came to a place where the tunnel had gone 
completely dark, and he had to crouch to his knees and feel his way along. When 
he touched the taut but yielding wall of the tunnel with his knees and his 
hands, he felt the drumming in his bones and realized that audio was built into 
the stuff; the drumming could be
anywhere, or it could be recorded. Or maybe it was a lot simpler than that, 
maybe the tubes happened to transmit sound well, and somewhere else in the 
tunnel system, people were just pounding on the walls.