But I had a problem. I had a copy of his outline, so I glanced at it. That's when it hit me with force that a message that would be clear to a reader requires special skills and adjustments to make it clear for a hearer. Consider the many built-in aids to clarity that occur in a manuscript that we lose when speaking. There is nothing in oral communication that corresponds to paragraph indentation.
Readers can go at their own speed.
They can re-read a section if they didn't get it the first time. They can benefit from visual cues such as italics, bold print, subheadings, and punctuation. They can look up unfamiliar words. Since oral communication has none of these things, a speaker must adjust if the message is to remain clear. Whenever you come to a key sentence in your message, restate it.