I have had this issue out of the box. I was just advised by Samsung tech support in Australia that they believe the sound issue could be resolved by a simple backup and reset. *Yet* to be tested since my screen cracked (and proceeded to spider crack over two days) on removing it from a flip case (the rubber surround not the hard plastic types) - which they will not cover under warranty (since the cover was not Samsung supplied), although I suspect (and so do 2 local repairers) was faulty to crack during cover removal.
You cannot simply replace the glass as with the S4 as Active does not have Gorilla Glass (funny, was advised otherwise by salesman - my fault for believing). If you do, there is serious risk the touch screen will not work or causing further damage in the repair, so, you must buy the LCD/Digitizer/Housing in one unit. A good 50% of the unit for more than half the cost of purchase of the new phone altogether...
Note: If you want a physical repair and unable to take it to your states repair centre (only in capital cities) then you are expected to courier your phone at $49.50 for a repair QUOTE. If you decide not to go ahead with their price at that time, they keep the $49.50. It is deducted from repair cost should you proceed but who knows if competitive with local repairers (local quotes around $340). Living 2 hrs south from Sydney I asked for a regional repair centre. I was advised of Granville.... not exactly regional. God help rural Samsung owners. THIS IS FOR ALL SAMSUNG MOBILE REPAIRS.
Do yourself a favour and consider another brand with better after sales service and support (better yet, a phone with no issues out of the box), with locations in your area or free postage as with Nokia, LG and some other phone brands have for me in the past (hence why I went the S4 active - water splashes etc). There were no approved repairers outside of Sydney in NSW
The Samsung S4 Active is a THROW AWAY when factoring cost to repair your purchase should any issues occur.
And for those who have only seen the fluffed up reviews around online IT IS NOT RUGGED. Tradies, look elsewhere!