The Pipe Organ is intriguing to view, but it's even more fascinating to hear. By humming into the "keyboard" under a canopy-like rock across from the formation, you can create a resonating sound within The Pipe Organ. Souvenir hunters of yesteryear who broke off stalactites exposed natural holes in the formation that create this musical effect.
By the way... don't try to take a souvenir of your own. You'll be warned at the outset of the tour that touching the cave's formations is a big no-no. That's because cave formations undergo a process of continual natural growth that can be inhibited if disturbed.