I setup a simple animation nodes node tree to experiment with the animation of a shape key and a material node of an object (cube). This is the node setup: Although, as stated in the comments below, this does not necessarily seem to be an animation node related issue ..
I added the sound sample in the video editor and then matched the animation end frame (140) to the length of the sound file strip. When I play the sound by pressing play in the timeline (still video editor) the sound exactly matches the length from start frame to end frame.
But when I change back to node editor and press play in the timeline the sound has already finished on a much earlier frame (like 87) but the animation will go on until frame 140 without sound.
I tried to tweak the all over fps value but with no success.. (and without knowing WHY exactly)
Any ideas what I miss(do wrong here? Thx ..