I'm sorry the problem was the Reminder sound in the Outlook Calendar does not
play.
Someone else had the same problem in another thread I thought I was replying
to and I had tried the steps that had been provided; running scanpst,
checking reminder settings etc., cleanreminders, verify it is the Outlook
Today default Calendar, etc.
I can no longer find the thread and 17 posts... But the good news is that
although I cannot "preview" the reminder sound by clicking the 'play' button,
it seems like the reminder sound does play when the appointment pops up.