Here is how to convert the “Subliminal” signal back to speech again:
1. Select the entire “Subliminal” audio track.
2. In the Audacity “Effect” menu, open the “Nyquist Prompt” and copy the following into the text field of the “Nyquist Prompt” window:
(defun ssb-demodulator (sound)
(highpass8 (lowpass8 (s-max 0 sound) 3000) 300))
(scale 5 (multichan-expand #'ssb-demodulator s))
Then click the “OK” button below the text field.
Do expect a very distorted speech signal, because there is not much “room” for sound quality in the range between 17500 and 22050 Hertz on a soundcard with only 44100 Hertz sample frequency. It probably sounds as if you shout with a megaphone into a telephone.
- edgar