Hello Kerstin,
I just saw in Sequence of 4 random events followed by a rating event as a block which will be looped through for all stimuli that there was a similar issue but no one ever got back to him 
I have to run the experiment on another computer and tried it on a windows machine. But there is the same issue. Do you still have psychopy 1.9.3? Could you run my code with some dummy sound stimuli? I can upload the .xlsx files. teststimuli.xlsx (8.7 KB) teststimuli2.xlsx (8.7 KB)