Sorry to bring something up again - I considered starting a new topic, but this only happens in RC7, and there's a similar issue on page 2-ish in this thread.
I still experience sound clipping, but not to the extent that it cuts off voice messages or anything like that. For example, hitting afterburner plays the sound relevant to the afterburner initiating - but it's quickly cut-off but the next sound, which is the loop of the burner actually burning. Firing subachs and prom's at the same time only plays the subs, with the prometheus sound occassionally playing. Flak firing rapidly, as another example, only plays one explosion at a time, and only for half the duration of the actual sound before it gets cut-off by the other explosion's sound; I.E. I don't hear two complete explosions simultaneously.
Another example is beams not playing a charge-up sound; only playing the sound of the beam firing.
The fix that Iss Mneur linked to works fine, as well as every other version of FSO that I have (including RC6). I feel this may have already been patched. I hope I'm not looking in the wrong place if this has already been patched for the next release.