If human speech is recorded and played backwards, mixed amongst the gibberish at regular intervals can be heard very clear statements. These statements usually appear in short sentence form and are nearly always related to the forward speech. It appears constantly throughout language, so much so in fact, that it is believed to be a natural part of our speech processes.
The pioneer and 20 year veteran of this field, Australian David John Oates, describes Reverse Speech as another form of human communication. He states that language is bi-level, forward and reverse. As the human brain constructs the sounds of speech, it forms those sounds in such a way that two messages are delivered simultaneously. One forwards, which is the conscious mind speaking, and the other in reverse, which is the unconscious mind speaking.
This is seriously amazing. I never knew such a thing existed. Go on the website and look at the examples and read some of the things that they present as evidence and stuff.