Not possible in the way I am guessing you were thinking, but there is a way to do it.
Create an Event that triggers at the start of a level. No conditions are needed. Add Actions to the Event that play sounds announcing the levels, such that the first Action plays a sound that announces the level 1, the 2nd Action plays a sound announcing level 2, etc. Press the Action Settings button and under the Sounds section, select "Play the next sound in order".
That's it. When the first level starts, the Event should be triggered, and the first sound should play. The next time the Event is triggered should be the start of level 2, and the 2nd sound should play. Etc.
If you only want announcements at the start of Rounds (and not Breaks), then you would want to add the conditions "isRound", so that the Event is not triggered at the start of Breaks.
The only trick is that any disruption of the normal flow of rounds would cause the tournament and the Event to get out of sync, so to speak. But that can always be fixed by simply checking or unchecking the "Performed" checkbox next to the appropriate Actions on this Event. For example, assume during round 2 of your tournament things were just moving too slowly and everyone agreed to jump ahead to round 4. Once round 4 is over and round 5 starts, only the 1st and 2nd actions would have been performed (the manual jump to round 4 would not have triggered an event, I believe). So the Event would get triggered at the start of round 5, but it would play the 3rd Action, announcing round 3 blinds. To prevent this, when you jump to round 4 edit the Event and check the Performed box next to Actions 3 and 4 .
Hope that's clear.