No sound in last frames of render.


I hope this is the right forum for this, scince it is more about the sound render than the video. I have go the problem, that always when I render a scene in Blender (Blender Render) with Audio, the last 3 frames of the scene a kind of muted. This happenes in all of the scenes I render with different origin sounds.

Does anybody have a clue what to do about it?