Stereo v surround mix content differences

[RodHQ]

I recently got my first 5.1 set up installed, and I've while I've been rewatching some old favorites, I've noticed a question tends to pop up into my head a lot "was that sound always there?"

Now, granted. Some of these movies I've only watched once or it's been a while since I did, but it did make me wonder, do 2.0 and 5.1 contain the same info? Does 5.1 add new sounds, or is it only the same sounds with the extra channels?

 

[William Lemmerhirt]

I recently got my first 5.1 set up installed, and I've while I've been rewatching some old favorites, I've noticed a question tends to pop up into my head a lot "was that sound always there?"

Now, granted. Some of these movies I've only watched once or it's been a while since I did, but it did make me wonder, do 2.0 and 5.1 contain the same info? Does 5.1 add new sounds, or is it only the same sounds with the extra channels?

Yep. They were always there. If listening to 5.1 or 7.1, or even Atmos, in stereo, all the sounds get folded down into 2ch stereo.