I've noticed this myself for my DSAI. As soon as the player dies and the "death cam" begins, you can hear all the sounds "said" by other units as clear as daylight. Weeeird.
Hm. Here's a random idea (completely untested): in ArmA, unlike OFP, I believe that radio commands that are said by a specific unit are actually said by the unit, not just transmitted to the radio net immediately. Thus you can hear the enemies shout things like "5, attack that...BARREL". But I don't think these shouts are "bugged" in the same way (since you don't start hearing a ton of battle chatter the moment you die).
Only problem with using the radio channel is of course that the "blip" sound when starting and ending are automatically applied, and I think there's even static automatically added to the whole clip. So that -might- not work. Then again, I've never heard the "blips" transmitted when your enemies are shouting in group radio, so they might not be audible outside. Also I haven't actually tried this with custom radio sounds, so I don't know if they're "said" by the unit or not...
Worth a shot?
Wolfrug out.