off the topic, but i will follow up byte's post.
i think changing the sound settings from the plist is a bit on the dodgy side frankly speaking.
back to my previous entries on iphone version 6, i did mention that a fellow customer had his diagram blown off as result of using the app to amplify the volume output. not recommended for us, as our iphones r not really covered by the warranty. a very simple explanation to this; our speakers is obviously not built to take that output capacity and strain.

therefore, piercing holes (on strategic locations-beware!) would prove to be a better alternative. coordinates are important to prevent tiny dust particles from entering the touchscreen portion.

did u remove the original screen protector?

i dont think its the screen protector cos never had this problem before. only happened yesterday. so must be either a software or hardware problem.

thanks