How do you spell the sound ghosts make?

There's no one agreed-upon way to spell the sound ghosts make! It's a sound that's often described as:

* Boo

* Woo

* Oo-ooo

* Hiss

* Shhh

* Eerie silence

It really depends on the portrayal of the ghost and the context. You can use any of these spellings, or even invent your own, to create the desired effect.