If you noticed your build file size in Unity3d (5.1.1) to be much larger then the editor.log suggests (almost 1.5x bigger). I suggest you look over your audio assets as issue Unity seems to be having an issue with misinterpreting sound file sizes.

 

If you have any large wav files eg background music, convert them to mp3 and in Unity use Vorbis as the compression format and compress in memory in Load Type. Just my 2c as There dosn’t  seem to be much knowledge around the web.