LWJGL playing sound effects in the update method?

So I load my sounds with slick and need a way to play them in the update method of my game. My problem is that if I call the playAsSoundEffect method, it’s being called in the update method, so it’ll play the sound 60 times a second. I thought “Okay! I’ll just make a boolean to run it once! like this:”
if(!sound.isPlaying())
sound.playAsSoundEffect(1f, 1f, false);

Well that didn’t work, as it just plays it again once it finishes playing. How can I accomplish this, where I call like a play() method and the sound is played ONCE? All help is appreciated!