A *.WAV file (or any other format, for that matter) is required to be converted into .AU format (Sun/Next) to allow direct use within Model Builder. There are various audio editing packages available however one we recommend is 'Cool Edit'.
Since the initial writing of this application note, Adobe purchased the rights to the Cool Edit software & the resulting software is named Audition. The instructions below were written with Cool Edit in mind, so may not match the steps needed to do the same thing in Audition.
Assuming you use Cool Edit, the process is (relatively) simple: