watermark.freesound.highfreq.wav

the text 'http://freesound.iua.upf.edu' made with noise at a frequency NOT AUDIBLE. If mixed with a common audio file (see examples in this pack) this file could be used as a digital watermark. You can see it looking at the spectrogram. In Audacity, for example, select the spectrum view instead of the more commonly used waveform view. To get a decent resolution the spectrogram should have a relatively narrow FFT band (1024 or above), results are best in grayscale. The original stero audio file was produced with GNU/GPL Enscribe 0.0.4 by Jason Downer, then converted to converted to a single channel with Audacity