To put it very short (if you will like it I will elaborate our idea in a more proper intro): we would like to propose you audio-banknotes, i.e. specially produced audio files whose duration is identical to the nominal value of the note, so one hour banknote is an audio track that lasts one hour. To protect it against counterfeiting Morten has produced audio-watermarks (a different watermark for each denomination) that could be embedded in the banknote. In the version we send you now the only thing that is audible is actually the water-mark itself - you can listen embedded in the audio-file, or as isolated water-marks on http://0o0o0o0.org/time/
Let us know what you hear.