I thought it would be fun to create a list of ways the sound of the TARDIS (de)materialisation has been described. With so many spin-off books, many writers must have given it a go. Here is what I've got so far:
Decalog 3, Consequences
"a screeching, grinding roar, somewhere between a raging elephant and a protesting asmathic" Continuity Errors, Steven Moffat
2006 Annual
"tremendous groaning sound" Doctor vs. Doctor, Gareth Roberts
"terrible wheezing and groaning" What I did on my Christmas Holidays, Steven Moffat
2007 Storybook
"a really really strange noise like an old car engine" Cuckoo-Spit, Mark Gatiss
"a gusting, grinding noise that rose and fell like old winds grating across one another" Once Upon a Time, Tom MaCrae
"unearthly noise [...] a scraping, rasping noise[...] the noise had sounded like a hundred coffin lids creaking open..." Gravestone House, Justin Richards
2008 Storybook
"a terrible, wheezing, groaning sound, ancient engines straining" The Body Bank, Gareth Roberts
"a noise of- what, engines? Or something like coughing?" The Box Under the Tree, Robert Shearman
"vworping brouhaha" and "wheezing, groaning noise" Zombie Hotel, Paul Magrs. The former also used in his novel: 'Sick Building'.
"roar of ancient engines" The Iron Circle, Nicholas Briggs
2009 Storybook
"A short of trumpeting. Rising and falling like a rusty engine turning over. Like Erkki's old car with the chains on the tyres" Cold, Mark Gatiss
"what sounded like a herd of trumpeting elephants and the creaking of rusty chains" Island of the Sirens, Keith Temple
"a noise like a strangulated elephant [...] the wheezing of ancient engines" Hold Your Horses, Nicholas Pegg
More quotes, please? And what about your own personal way of describing the sound? I know there are fic writers among you.