Thanks guys

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@Steve ... as a matter fact, I'm pretty sure that I saved one or two of the ogg files in stereo, 'cause I figured it would maybe sound better, but the originals were mono. I suspect you've hit the nail on the head, and I'll have a look at that first

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edit/add: Oh, btw, one thing I was messing with was the relative volume of different sounds which play at the same time. eg background hydrophone noise and own prop noise. I was adjusting them by tweaking the volume in the sound file itself, but I'm finding that when they play in-game, they're not getting the relative volumes that I thought they would. I'm thinking that there must be a controller file which adjusts/controls the sound file volumes. What file would that be (if I'm right) and can it be tweaked? :hmm: