They are offering a free trial for 20 minutes or 20 farts at the link in the artocle. If you like the app, you can pick it up for a reasonable $1.99 in the Berrreview.com store.
Nice! Or you could just record yourself farting a few times with the Voice Recorder! Or record fart noises with your mouth! That way you don't accidentaly **** on you phone!