This is a question about manipulating sound (wav files).
The goal is to produce something that sounds like a number station broadcast, see e.g., 4:00 in http://www.youtube.com/watch?v=EdnoAJ7KoFE
It is easy to generate a random string of numbers,
and send it to the linux program
-v de for German and
-w out.wav for saving the sound as a wav file.)
Now, the resulting voice is too clean to sound like a radio recording, so the challenge is to distort the sound a bit and make it sound more like a strange radio recording. Adding a little echo and some white noise maybe?