Actually, breakNum will be greater than 0 once the first break occurs, and will continue to remain greater than 0, meaning that would trigger at the start of every level.
Set the conditions to "!isRound". Also, you can add multiple actions that play sounds. So add an action for each sound you want to play at each break. Then press the Action Settings button, and in the Sounds section select "play the next sound in order". That will play the sound for your first action at the first break, the sound for the second action at the second break, etc.