I just set it to if the jump key is pressed and the player is on the ground it plays the sound. The only problem I have with that is that if the player is bunnyhopping then the sound only plays on the first jump, although its not to major of a problem because the sound isn't all that pronounced. Also, I don't think there's any reason to put in the 'alive' value because when the player dies it destroys it, so its not on the ground, although I might be wrong about that... I should test it.
Anyways, I'm uploading an update version with a different ending that should work consistantly, although I haven't played to it yet so I can't tell for sure. I've also assigned the jump button to Z. I tried to assign it to Z and the up arrow but the Z jump would act differently than the up jump and I couldn't get it to work right. Anyways, here's the file:Download