Silent Subliminal Presentation System
A silent communications system in which nonaural carriers, in the very low or very high audio frequency range or in the adjacent ultrasonic frequency spectrum, are amplitude or frequency modulated with the desired intelligence and propagated acoustically or vibrationally, for inducement into the brain, typically through the use of loudspeakers, earphones or piezoelectric transducers. The modulated carriers may be transmitted directly in real time or may be conveniently recorded and stored on mechanical, magnetic or optical media for delayed or repeated transmission to the listener. in 1992 a US Patent was issued for exactly such a thing, which described what was referred to as a “Silent Subliminal Presentation System”.
The idea stemmed off the subliminal learning tapes that were sometimes used while people sleep to help them try to kick a bad habit such as smoking. It was understood that subliminals didn’t need to be visual, and that audio subliminals worked just as well, but this specific method was able to get the desired audio subliminal affect, but do it in a way that is completely silent, through the use of ultrasonic frequencies, which the human ear can’t hear, but the human mind can still decode.