Facial muscles are important because to use them can ‘make your face live’, providing animation and life through talk. An expressionless face can be taken by those listening as meaning the speaker is not really interested in what she or he is saying. Speech is helped by a ‘living face’ and pleasant expression.
Most of the time, conference and audience pictures are simply of people sitting and listening. Is there a chance that conference ‘action’ pictures might show people engaged more interactively in participative opportunities offered by presenters?
Maybe a weakness of presenters and their presentations is the fact they go on and on and on. Interactivity between presenter and the audience can add to the dynamics of the presentation.