boss_ent thread breathing(); // This in boss code to thread it

breathing()
{
  self endon("death"); // This is to end the loop, when boss dies
  while(isDefined(self)) // Another check for boss being alive, just in case
  {
    self playSound("your_sound_alias_entry"); // Remember to modify this to have your sound
    wait given_time; // Change this to wanted time. Make sure its longer than sound, otherwise it will overlay, when played again
  }
}

breathing()
{
    self endon( "death" );
    self endon( "delete" );
    while( isDefined( self ) )
    {
        self playsound( "SOUNDNAME", "sound_done", true );
        self waittill( "sound_done" );
        wait( randomfloatrange( 7, 18 ) );
     }
}