Silent Subliminals [solved?]

Better quality conversion of the “Subliminal” signal back to speech again can be achieved like this:

(defun demod (s-in cf)
   (mult s-in (hzosc cf)))

(multichan-expand #'demod s 17500)

This assumes that during “encoding” a carrier frequency of 17500 Hz was used. If this is not the case, change the number as necessary.