Or two iOS devices...

You can also use the device in a single device mode (with headphones), as shown in the second video. I just thought that the dual device mode would be more interesting and therefore emphasized it in my submission.

Thanks for clearing this up! I will use the word accuracy in the next update!

Nobody in their right mind would buy two iOS devices just to use this app. But somebody who's got two of them already might consider buying this app for under a dollar. (Just one purchase required if you have both devices on the same iTunes account.)

Please watch the second video, it shows how the app can be used with just one iOS device and headphones.

I agree that by having the clocks exactly synchronized this could be a lot easier. (But even 1 ms of deviation means an uncertainty of around 34cm.) The challenge was to do it without having the devices synced by an external source (it works on iPod touch devices and iPad as well) and without using a communication channel other than sound.

Minor correction: the so called one time pad is easily proven to be uncrackable by any method. The only problem with it, of course, is the key exchange. (The key is as long as the message, and needs to be securely transferred beforehand.)

The "App Store lottery". That's what I keep reading on developer forums. But except for buying a ticket you have to work really hard creating an app or game.

I hope to hit the jackpot with my newest app called Acoustic Ruler Pro which lets you measure distances of up to 25 meters (82 feet) by clocking the time delay of the emitted sound waves.

Here are two short videos showing what the app can do: http://iqtainment.wordpress.com/acoustic-ruler/.

Hello, anonymous submitter,

About I year ago I've started a small project with a friend, written in C++, that does some improvements to lossless audio compression (currently to FLAC). It calculates the autoconvolution of the audio signal to find similar parts in the audio. Especially for electronically generated music, this can be used to predict other parts in the audio, and thus reduce the entropy of the signal (i.e. compress the file better).

If you (or anybody else) are interested in further development, I would open-source the project, and may be start working on it again a bit myself. Just drop me a line, at polarspaceflo (at) googlemail (dot) com.

I recommend you find some source code virus, one that finds a source file and copies itself into the source file... While it has to rely on somebody compiling the source in order to spread (if it is written in a compiled language), this is easier to understand and analyze (and remove!) than a "binary virus"