I'm currently learning to play Comptine d'un autre été from Yann Tiersen (Sheet music(pdf) - youtube video) and when I play starting from the 13th bar I barely hear the notes my right hand plays.
Obviously I should play my left hand less loud but this seems a hard thing to do for my brain as it seems to play both hands in the same volume, and when in some occasions it works to play some of them quietly, the timing is off between the notes.
What are some good techniques to learn to play one hand less loud than the other whilst the timing stays correct?