Quite excellent.

I wonder why people are having a hard time seeing the usefulness of this app. It worked well on my 3G, and seems to be working even better on the iPhone 4, perhaps due to the faster processor. I find the "wind" preset to work the best, with rain a second-place. Turn up the sensitivity, and it works even better. I find this well worth the cash.

OnlyShawn about SoundCurtain