What exactly are subliminals and how do they work?

[sunnycat]

Title

[HypnoEMG]

A subliminal is a file where the audio portion is barely audible or masked with music or some other sound. The theory is that your subconscious mind will process that information and accept it much the same way it does hypnosis.

[Crowb]

Can it be completely unhearable? (hmmm, now i see how stuff happened; put it at same loudness as file and so i got 3 voices talking the script canon and i couldn't hear a thing xD)