For some reason, the audio volumes for Ep2 are inverted for me… for example, sounds that are produced behind the player are always louder than sounds produced in front of the player, whereas it used to be the other way around.
The same thing with distance: the farther away a sound is, the louder it is, and if sounds are produced directly in front of the player, it is practically nonexistent.
I am confused. This just started happening and hasn’t happened before. 
Change from 2 speakers to headphones or vice versa.
It’s been like that (2 speakers when I have speakers, headphones when I plug in headphones). Haven’t ever encountered problems with those settings before.
I just started having the same problem yesterday with my 5.1 sound setup.
This is by far one of the trippiest glitches I’ve ever heard of. Tried updating your sound drivers?
Yes I have. It only happens on mods for me.
Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.