Here's what I observed over thirty years of teaching communication. It's important for today's author to be a good speaker, because we must present well before agents, editors, and audiences of potential readers. While I would hate to think we compete with each other, we are compared to other writers as we sit on panels, in pitch sessions, and so on. Many times I've bought books based on the impression a speaker made on me at a convention. Nevada Barr springs to mind; she has such a presence on stage that I wanted to read what she'd written, and it worked. Other times it doesn't turn out quite so well, but the impression an author made during a presentation had an influence, even if I only bought one book.
Listening, too, is critical for authors, and we often neglect that skill. Missing the nuances of tone and expression, sometimes even missing the words themselves, is common, especially when the listener's situation is fraught with nervousness. What exactly did that agent say? Was I too busy thinking of how to appear clever that I missed the hint of truth behind the polite phrasing? It can even be more specific: Did the agent say to send three chapters and a five-page synopsis or five chapters and a three-page synopsis?
So as writers, we have to sigh and admit that improving the other communication segments is almost as critical to our success as becoming better writers. We have to speak well and appear confident as we do. We have to listen well and sift through the chaff of all we hear in a day, finding the kernels of truth that we seek.
The last word on speaking and listening? After thirty year of observation, that one's easy: PRACTICE.