If you play media, music, videos or whatever uses the speaker, it plays only via the only speaker at the bottom. What this mod does, is that it enables all the speakers including ear piece speaker and thus enables the real surround sound for your device.
And how to install it? Well, it's actually pretty simple. The only thing you have to do is to flash a ZIP file in recovery.
(custom recovery needed)
What more to say, just enjoy your upgraded sound!
(If you don't like the changes, you can revert back by flashing this ZIP).