So folks, after I played through the fifth chapter of the german version of the game, which was really annoying in reference to the occuring sound problems, I changed to the english version, where I couldn't find the same failures. It worked fine, though I didn't get warm with the synchro.
But one thing took my attention: the speaker of the english version are talking very fast in comparison to the german ones, just as I mentioned in an earlier post. I'm sure, that the cuts at the end of some sentences aren't a problem of the hardware of my system, jumping to conclusion, I'm nearly confident, that this won't be a problem of anyone, who plays the german version of the game, either. It would rather be a sheer coincidence.
I hope you will take your moneymaking in germany more serious in the future. We are not as stupid as you think. Nobody will buy games from you, if you don't learn from your own mistakes.
I regret buying the full game, before I even played the first chapter. wish you luck with the second season, I will spend my money otherwise, not to lecture you, but to avoid your traps.