I'm spending the weekend in Northern Arizona on a photo shoot. It's dry up here, but I took along a little iPhone/iPod touch app that put me in the center of several dramatic thunderstorms.

The app is called Thundergod [iTunes link]. With creative microphone technique, and a good set of headphones, you'd swear you were in a raging storm, or a rain forest, or one of 5 other environments, listening to nature at its most spectacular. You can listen and let your mind drift off, consider the state of the universe, or just fall asleep in a soft rain using the built in sleep timer.

I suspect the techniques used to make these recording are similar to the highly regarded binaural technique, using 2 microphones separated by the approximate distance between your ears. Then when you play back with good headphones, you are instantly transported to a hyper-realistic, almost holographic place that closely duplicates being in a real space with real sounds.

This effect doesn't work through speakers. It can sound nice, but it's not startling or compelling. With headphones the sound comes alive, and you can begin to have an emotional reaction to what you are hearing.

The app also allows for a special equalization curve if you are using earbuds like the ones Apple includes, and it is effective. This app as produced by Holographic Audio Theater, who gave us the free app Naturespace that shows off their recording and producing prowess. It's a good introduction to their technique.

Thundergod is not cheap. It's a U.S. $9.99 app, but of you look at the App Store reviews you'll be surprised how many purchasers thought the app was worth the money.

The sounds are not short repeating loops, but something like a long concert that has a beginning, a middle and a conclusion. I liked the 'Thor' environment the best, because it was the most dramatic and attention-grabbing. It's not for relaxation, but for stimulation. If relaxation is what you want, there are sonic environments included for that as well.

My suggestion is that you try the free intro app, and if you like it, then go ahead and get Thundergod. The effect can't really be described, but must be experienced.

Naturespace [App Store] for the iPhone and iPod touch is a free app that lets you sample very natural and realistic sounds to relax to. They come from the folks at Holographic Audio Theater, who produce some very serene audio tracks for meditating, relaxing, or helping you sleep.

The app itself is attractive and easy to use. It provides 5 different audio environments for headphone listening. While there are some other nice apps that provide similar features, I thought this had the best audio and the most enveloping sound I had sampled. I especially liked the sound of waves lapping on a beach because of the gentle right to left movement.

I listened on both regular headphones, and iPhone earbuds. The software has a switch to turn earbud equalization on, and it did seem to deepen the bass and improve the realism of the presentation.

The app is very well thought out, and if you change to one of the other ambient recordings the sounds slowly fade down and then the new selection fades up. You can go to sleep using these sounds and turn on the iPhone sleep timer. The developers will be glad to sell you additional low cost ambient recordings, but the free app is not crippled in any way and has no advertising. The positive reviews at the App Store are a pretty good indication that this is a well conceived piece of software.

This app will be worth a couple of bucks to many people, but since it is free, I think it's a no-brainer to try and see if you get swept into the sonic environments that are provided. The loops are seamless, so there is nothing to interrupt your reverie as you s l o w l y... r e l a x... a n d... b e g i n... t o... n o d... o f f ...........

Here are some screen shots: