In a fantastical bit of communication irony, Alan Greenspan is credited with the tongue-twisting line "I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant."
However, the earliest known print attribution of the quote comes from a 1984 TV Guide edition and is credited to Robert McCloskey, a U.S. State Department spokesman during the Vietnam era.
It's a beautiful encapsulation of the George Bernard Shaw quip, "The problem with communication ... is the illusion that it has been accomplished."
That brings us to the process of communication.

To communicate: a sender (me!) encodes a message (the English language!) that is then sent using a channel (this blog post) and is decoded (language norms) by a receiver (you!).
It's straightforward.
But noise—the all-encompassing metaphor—inhibits the ability to communicate effectively. Communication noise is all the things—preconceived notions, biases, ineffective channels, language understanding, emotions, technical knowledge, etc., etc., etc.—that influence the interpretation of conversations and prevent successful communication.
And that brings us back to the McCloskey/Greenspan misattribution: "I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant."
This quote, I believe, gets to the root of innumerable organization problems—unsuccessful communication: ignored HR announcements, boss/employee expectation conversations, new (or old) policy diffusion, poor execution, work process breakdowns, and a long list of a lot of other things.
Communicating well is surprisingly difficult given how much we do of it.
That brings us to the last component of the process I've yet to mention: feedback—the receiver's response to a message indicating their level of understanding. It is in feedback—head nods, raised eyebrows, clarifying questions, statements of assurance, etc.—where we learn whether or not our intended message has been understood by the other party.
I believe it is most often the absence of appropriate feedback mechanisms where otherwise successful workplace communication breaks down. It's the result of full email inboxes, large group settings, rushed meetings, and the like.
So improving communication at work begins with recognizing communication as a process and ends by embracing the all-important (but often ignored) feedback element of the process.
Because as George Bernard Shaw reminds us, communication hasn't happened until the sender has been assured the receiver has understood the message.
Absent feedback, communication is an illusion.