I don't see that setting in my accessibility settings so I'm guessing its off?
It might be called something different on Touchwiz (I'm using a Google Edition ROM on my S4 so I can't check) but there is definitely a setting somewhere for assisting people with vision problems by speaking things out. I'll try to look it up.
edit: system settings -> accessibility -> text to speech -> driving mode?
edit2: People are saying Lightflow can cause this issue, are you using Lightflow?