void main()
{
    object oTarget;

    // Get the creature who triggered this event.
    object oPC = GetEnteringObject();

    // Only fire for (real) PCs.
    if ( !GetIsPC(oPC)  ||  GetIsDMPossessed(oPC) )
        return;

    // Make changes to the sound object "croydecaveyells.
    oTarget = GetObjectByTag("croydecaveyells");
    SoundObjectStop(oTarget);
}