Shannon what do you think

[Shannon]

I have jus read this in an audio forum where they create subliminals, is this true
 There had been a predecessor "ultrasonic" plugin in the german Audacity forum, that had originally been written for a dog training school. They had a 192kHz soundcard playing ultrasonic "dog commands" over a piezo speaker system. The dogs, who can hear ultrasonic sounds, then learned to do things according to the signals, where the humans hear nothing. Some time later I was notified via some posts in the german Audacity forum that people reported success by using the "ultrasonic" plugin to produce subliminal messages. To me it was instantly clear that the "ultrasonic" plugin couldn't work on a 44100Hz soundcard because the signals produced by the plugin were above 30000Hz, which cannot be reproduced with 44100Hz sample frequency. In some subsequent discussions I prooved several times that the "ultrasonic" plugin with 44100Hz sample frequency only produced signals containing not more "message" than contained in dust-buster noise, but people were still continuing claiming "astonishing success"

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.
The sound quality is poor because for a sample rate of 44100 Hz and a carrier frequency of 17500 Hz, the audio bandwidth is less than 4500 Hz, which is not enough for high quality audio. You will need to use a lower carrier frequency, or a higher sample rate, or a different method for making the voice "silent

Assuming that they are AM encoded, the upper limit for 320 kbps MP3 is 20000 Hz. For the message to be "silent", the carrier frequency must be at least 15000 Hz, so at best the audio band can be no more than 5000 Hz (just about enough for voice). So that means that you can do the filtering in two stages and get virtually complete isolation.

I'm not sure what you're wanting to know here.