Replacing sounds?
 

I tried replacing some of the explosion sounds of the depth charges because they don't sound as intimidating enough.

I located the one sound that is the sound of depth charges you hear from the submarine,its called:
Depth charges exploding from submarine.wav

I downloaded a sound I liked from a sound effect website that is also .wav format and renamed it to replace the original.

But it doesn't seem to work in the game,there isn't any sound.Is it because of the length of the sound,the one I downloaded may have been a bit longer than the original.

This is the sound I downloaded,its the last one called big bomb:
http://soundbible.com/suggest.php?q=depth&x=15&y=12