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I've noticed that at times the game was really quiet, like in the sewers, when standing right in the middle of the waterfalls, there wasn't any sound - or, on the contrary, some sounds were buggy, as when standing near a flame, I could hear a loud crackling closer to a loud white noise than a nice fire spluttering.

My soundcard sampling frequency was at 48000hz (DVD quality). Turning it down to 44100 (CD quality), all sound issues were solved.

So if you hear something odd (or hear nothing), try this on your soundcard settings or Windows Sound panel. I know this helps with other old games too.