Hi Brett,
You can actually hear a recording of the ping hitting a submarine as recorded from the inside! The recording appears to have been made in the 40s or early 50s (it was declassified by the USN in the early 60s and released by a sonar development company, apparently). I found it yesterday, and that is what I based the new sounds on.
You can listen to it here:
http://www.hnsa.org/sound/soundinthesea/track32.mp3
I think I got it pretty dead-on with Mk IIB, but I may need to make it a bit louder. My plan is to keep the impact sound at the same volume (or maybe *slightly* louder), and then make the squeak sound of the ping a fair bit louder.
This way, when you are hearing the ping without the enemy getting a return, you will hear the squeak and not really hear the impact very much. Then, when the enemy is getting a return (and your SO says "Enemy is pinging us, sir!"), the game turns the volume up on the ping sound, and that should make the impact audible. I'll probably release Mk IIC tomorrow.
I've got it so that it works pretty well on my own sound set-up (I play with headphones on mostly), but it will produce different results on everyone's rig. This is a limitation of the game - ideally, I would be able to have two sound files (ping with no return, and ping with return) and the game would alternate between them based on whether or not you were in the sonar cone. Haven't yet discovered if this is even possible, but I suspect it is not. What I have done with these files is the best possible compromise I can think of, so far.
Thanks for the links you provided, by the way! Neat stuff. I was actually going through the freesound website's pings yesterday, but they were all modern ping sounds.
