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

"click 1 d.wav" from TicTacShutUp
http://freesound.iua.upf.edu/samplesViewSingle.php?id=406
License: Creative Commons Sampling Plus 1.0 (http://creativecommons.org/licenses/sampling+/1.0/)


