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;
};