When I attempted to import the file directly into GarageBand to add music, credits, disclaimers, etc., the audio would play sloooooowwwwwly. I couldn’t understand why. Some of my co-workers in the audio production department at Audible suggested that it might have been a problem with the way the application wrote the headers on the files. Subsequently, I would convert the AIFF file to WAV and upon import into GarageBand, the WAV file would play just fine.
I was recording at a 48 kHz sample rate. GarageBand expects a sample rate 44.1 kHz and more importantly, it’s not designed to downsample the file in order to play it back properly.
Who woulda thunk it?
Now I’ll know what to do when it happens in the future. Thanks to the iLifeZone gang for the solution.