King Benjamin goes to considerable effort to make sure that the people receive the message. First he causes a tower to be built so that his voice can project to a larger audience. However, that is not enough. The multitude is too great and they cannot all hear his words. This is unacceptable to Benjamin. He has his words written and delivered to the people. One can imagine that this task alone would be a great amount of work without the benefit of voice recognition transcription software and copy machines. Having done all this, when Benjamin had finished, he sent among them, desiring to know of his people if they believed the words which he had spoken unto them (Mosiah 5:1).
Neal A. Maxwell
"So concerned was Benjamin with his major sermon that he sent among the people to see if they really believed in his words. Benjamin was much more concerned over connecting with his spiritual constituency than with his political constituency. He was continually concerned about communicating." (John W. Welch, and Stephen D. Ricks, King Benjamin's Speech: Made Simple, p. 3)