It seems if you use a custom AudioDescription, no one but the host can hear it.
I have noticed how Stratofortress' Blackhawk does not have a working one either, and he defines a custom AudioDescription too.
datablock AudioDescription(ClockTowerBellDesc)
{
   volume   = 1;
   isLooping= false;
   is3D     = true;
   ReferenceDistance= 125.0;
   MaxDistance= 750.0;
   type     = $SimAudioType;
};
datablock AudioProfile(ClockTowerBellSound)
{
   filename    = "./bell.wav";
   description = ClockTowerBellDesc;
   preload = true;
};