Claude Shannon was a research scientist at Bell Telephone Company trying to achieve maximum telephone line capacity with minimum distortion. He had never intended for his mathematical theory of signal transmission for anything but telephones. But when Warren Weaver applied Shannon's concept of information loss to interpersonal communication, one of the most popular models of communication was created.
According to Shannon and Weaver's model (as seen above), a message begins at an information source, which is relayed through a transmitter, and then sent via a signal towards the receiver. But before it reaches the receiver, the message must go through noise (sources of interference). Finally, the receiver must convey the message to its destination.
Suppose you have an idea in your head (information source) that you want to tell someone about. You must first move the idea from your brain to your mouth (transmitter). Since you cannot actually share your gray matter, you must select words for your transmitter to use. Once you speak, your voice (signal) is carried through the air toward the listener's ear (receiver). Along the way, your signal is joined by a myriad of other sounds and distractions (noises). The receiver then takes everything it receives and tries to maximum the message and minimize the noise. Finally, the receiver conveys its message to the other person's mind (destination).
Shannon and Weaver's model clearly demonstrates why even the simplest communications can be misunderstood. Transmitting a signal across additional media only adds to the complexity of the communication and increases the chance for distortion. It is suddenly easier to understand why other people just can't grasp what we already know.