Re:English speakers (Score 1)

I agree. The person who gives the presentation most likely knows what he is saying, but for the audience it is likely the first confrontation with the subject (or a decision, point of view, ... about it).

They have absolutely no need for difficult words. Using normal vocabulary will make it easier for the audience to understand you.

Also the vocabulary has to be adjusted to the audience. Talking to 17 year olds is not the same as talking to scientists :)