I interviewed Bert Decker on this weeks' Duct Tape Marketing podcast show. I first ran across Bert when I initially determined I needed to learn how to get good at public speaking about 10 years ago. (Something I'm still working on.)
Bert wrote a fabulous and fascinating book on the subject called You've Got to Be Believed to Be Heard. This book sheds great light on how the human brain perceives the message you are communicating, whether it's one on one or to a group. One of my favorite quotes from the book is attributed to Emerson - "Who you are speaks so loudly, I cannot hear what you are saying."