Although I have not heard the audio tapes to tell you if they work or not, I can definately say, yes! they do work. And I can say this without even listening to the audio tapes because its a proven fact that individuals are able to learn and listen in their sleep. I am not a college professor nor am I at the top of my class when it comes to difficult problems. I just know from experience that you can learn in your sleep. I have left the T.V. on plenty of times to tell you, I know exactly what they where saying and what the topic of discussion was about without even having to be phisically awake.