Have tried all corrections listed in Goole to get video along with voice when using FaceTime. All this trouble start with downloading IOS9 and cannot seem to fix the problem(s).
So, when face timing, you get video w/o voice? have you checked the basic steps like checking the mute and volume buttons?
If you directly link it to iOS9 update, have you tried restoring? or setting up as new? If not, first back up your device, and see if restoring as new, fixes the issue.