Cave Rave

Cacophonous and crowded, and it stank,
Assaulting and confusing, never ending.
He tried to get the groove. He drew a blank,
But just for her he'd have to keep pretending.
She tugged his shoulder till her mouth was nearly
Inside his ear. She shouted. Even then
He struggled to make out her message clearly,
And had to make her yell it all again.
"Relax and focus far, beyond the beat
To hear the hidden image sounding through.
Ignore the rhythm shifts in each repeat.
You'll feel the magic scene pop into view."
  He did: a 3-D marvel filled the cave.
  They let go of the ceiling, joined the rave.