You can hear a preview of the audio book with a short clip of Philip reading from Fever Crumb here:
Despite having no free time at all lately, I've read five and a half of his Mortal Engines books since I met him at the Edinburgh Book Festival, so I guess that pegs me as a rather keen fan. (And you can read his review of Vern and Lettuce here!) Hopefully the Fever Crumb audio book will come out next year, in March, to tie in with the launch of the paperback in the United States.