This ability is PERFECTLY fine. Remember, when you're in a world where you NEED to adapt and hone your senses, your hearing will be more sensitive and effective. Joel being able to do this makes total sense. 20 years of surviving in this world will do that. Besides, you are very vulnerable when using this mode (from what I've heard.)
Awww Yiss, clearly the Naughty Gods were listening and have answered my prayers. They've made this (the wallhack listen mode) an option in the settings which you can toggle on/off.
You can also toggle game hints, lock on aiming, and a couple other things on/off. Good call on all of it!
And what do the "hardcore" have to say about this decision? http://www.neogaf.com/forum/showthread.php?t=55884
only 3 1/2 more weeks of waiting....sigh....