1) Dowload the file (taken from the original french demo, repacked and uploaded) here
https://drive.google.com/file/d/0B45YJj6bhfxaSlpOSG5Ga3R1UlE/view?usp=sharing
and save it anywhere you like.

2) Extract the file into the game folder (normally Steam\Steamapps\common\Sinking Island)
So the included file OPDSound.dll will be in Steam\Steamapps\common\Sinking Island\modules overwriting the existing file.

3) Start the game and enjoy the game the way it was meant to be.

Like already said the file was taken from the french demo version of the game. In case you don't trust the uploaded file feel free to search for the french demo yourself by googling "lile noyee demo". You will be able to install the demo into any folder you like to get the file needed extracted.

No matter if you should use the fiel included in my archive or the one from the french demo be aware that you do this at your own risk. I tested the file by loading a savegame near the end of the game and everything worked fine. However this is not a guarantee that the file could not lead to any other problems. If you should experience any problems and you supect the file to be the reason simply verify your game files and steam will download the original file - without any lip movements. I also like to add that I tested this only with the German version (being German myself) so no guarantee that this will work with every language even though I do think so.