Help, please!

[stopwatch_plz]

Ok, I'm sure this has been asked a zillion times before, so I'm really sorry if it has - I did look in the FAQs and posts and couldn't see anything, and I'm a bit of a n00b, so please be nice!

Anyways, my question is thus:

How do you write the sound of the TARDIS dematerialising? o_O

TIA