As a matter of fact, both are required. A good modulation of the voice with good vocabulary added to the subject knowledge will always make the talk attractive.
The talk must be addressed to the audience. It is best to avoid large expressions that are too digestible for the listeners. Speeches should be tailored to the quality and mood of the listeners. It is understood by the audience, and the speaker is responsible for resolving their doubts. Only take such a venture into such adventures if you can do it perfectly.
small drops make a mighty ocean
But the theme of the thread is intended something else that communication should be lucid and clear with all required details. I agree with it that communication should be understood fully by all people who are listening to this communication. I don't like ambiguity in speech or written work because it creates a communication gap between speaker or writer and audience or reader respectively.
Here the author has stressed that communication should be clear so that the other party understands fully and there is no ambiguity in it. This can be achieved through the practice and if we want to have these things to be included in our conversation, it is better to write the relevant points in our note books so that these things are represented in course of conversation.
"Life is easier when you enjoy what you do"
Knowledge is power.