In working on an app recently I reduced many of the sound files from 16-bit mono to 8-bit mono which cuts the sound file size in half. However, it proved to have an adverse effect when using certain programs. Goldwave and Audacity seemed to add static to the sound.
From what I have read, it has something to do with the algorithm that makes voices more audible, which is why the static is in areas with sound and it ceases when there is silence. Soundforge32, an ancient program that I've had since the early 90s didn't have this problem, reducing them to 8-bit without the static-causing sound dithering.