Yass uses the following sound files from Freesound (http://freesound.iua.upf.edu): 

License, unless otherwise mentioned, is Creative Commons Sampling Plus 1.0
http://creativecommons.org/licenses/sampling+/1.0/


editor: "click 1 d.wav" 
(c) TicTacShutUp
http://freesound.iua.upf.edu/samplesViewSingle.php?id=406
