Without having to download & check your audio files, are they by any chance in mp3 format?
Mp3 support was unofficially dropped from VS, though sometimes they work & sometimes they don't. I recommend converting all your sounds to ogg (vorbis) or opus format. Stick them in same folders as they are located with same names after converting & then open up ved in a text editor like sublime text, github atom or notepad++ then select all & search for ".mp3" then do a replace all & change the extension to whatever you converted your files to.
P.S: if you are going to edit your ved in a text editor then I recommend backing it up first.
* edit: downloaded it anyway. I see there's only 3 sound files. Convert them to ogg (vorbis) format with audacity & then replace them in the editor & you should be good to go.