well, there are many posts like this in this forum. So, you might want to consider searching first before posting.
Anyway, change \ to / Check the spelling of your files. While PsychPy is “tolerant” to spelling errors (case, different extension), PsychoJs is not. Is the file available for online use? So, do you have a directory datittrials/audio which contains provaa.wav? How do you load your stimuli? Notice that wav is a windows-file format. Consider using mp3 for online experiments.