Very good post! Your are so right! It is very important to speak clearly so you say what you want to say and also to listen carefully so you listen what the other person wants to tell.
Many many times we want to say one thing but efctively give another message, and also you listen what they tell you but you don't pay attention and understand something else.
Also, in business environment is a good idea to communicate by written media so people can go back to the message and ready it as many times is required to completely understand.
Nice article!