How do you make people listen?

One of the great secrets to efficient communication is: limit the length. The shorter the better. All TED-talks are less than 20 minutes long. Perhaps the most famous speech of all time, 'I have a dream ', Martin Luther King, spoke in 17 minutes. The inaugural address of John F Kennedy took 12 minutes. And the legendary Abraham Lincoln's Gettysburg Address lasted 3 minutes only. The wording of that speech was so impressive that it is chiselled on a column in Washington. Why should you speak any longer. An adult's attention span is on average 10 minutes.