I have configured Calendar on my Mac to give an audible alert and show a notification when an event begins. However, this is nothing like enough for me – I still regularly miss meetings or arrive late because the single system tone doesn't interrupt me sufficiently to ensure I process the alert. It is also annoying that the alert sound seems to use the system beep, which I'd generally like to have be quiet.
Is there some way to have Calendar alerts start an alarm that I need to actively turn off? If I need a separate app to handle this, that would be okay.