Quite recently on certain TV progs I can hear a voice in the background .Where you get subtitles for the dialogue this voice is setting the scene ie" "John goes over to the picture on the wall he takes out his glasses to study it"
or " the lady in the white coat gets into a taxi" It's driving me up the wall,have I pressed a button somewhere ? It seems as though it's a help for the partially sighted or blind.
It sounds like you have the audio descritpion option enabled - this is intended for blind or partially sighted people to aid their understanding of what's happening. There will be a way to find it and turn it off from the menu on your handset.
You must have accidentally pressed the "Audio Description" button. To turn it off press the button marked AD. Exactly as you say, it's for the partially sighted/blind viewers.