When making an oral presentation, a skilled presenter will use the full pitch range in order to structure and segment their monologue. Pitch can be useful in a presentation to highlight, among other things, the division of the talk into spoken paragraphs (paratones). Less skilled presenters often use a narrower pitch range which gives them less headroom in which to show these divisions.
Consider the two pitch traces below. The first one is taken from a student of English doing an oral presentation; he is a relatively ‘novice’ presenter. The second one is taken from an experienced university lecturer. Visually, we can see how the expert presenter is making full use of the pitch range with sweeping highs and lows. The NNS novice, in contrast, has a much narrower pitch range.
This difference can also be perceived when we listen to the two samples. Click on the link below to listen to the audio sample. First you will hear the NNS novice, then you will hear the NS expert. Listen and compare the difference in the way the pitch of the voice (intonation) changes over the speech.