This is very cool! Kudos to the authors. I had the idea about this about a year ago (when style transfer for images was gaining traction), and wanted to do it in my master's thesis. I ended up doing something related, though: Evolving neural networks that transform sounds with the help of audio effects. For example, they can process white noise so it sounds like a drum loop. Sounds are available here:
http://crossadaptive.hf.ntnu.no/index.php/2016/06/27/evolvin...