Am I using CocosDenshion correctly?

Question

I have found a tonne of leaks in my code. All of them come about when I play a sound or a song.

Here is how I call a sound effect:

 [[SimpleAudioEngine sharedEngine] playEffect:@"myeffect.wav"];

Here is how I play a song:

 [[SimpleAudioEngine sharedEngine] playBackgroundMusic:@"mysong.mp3"];

Am I somehow supposed to be releasing these after they are finished or something?