The need to raise meaningful questions to the speaker stimulates active listening that can result frequently in a lively exchange of views. It also gives audience members an opportunity to express their views and it gives the speaker an opportunity to practice impromptu speaking under meaningful conditions. Questions can be asked about the speech preparation and presentation itself. Questions can be asked seeking additional information. Questions can relate to an audience member's disagreement.
Questions can relate to an audience member's agreement.
Questions can be asked about the evidence, or lack of, in the speech. Questions can be asked relative to the perceived purpose of the speech. Questions can be asked that seek clarification of a point. Questions can be asked about the problem from which the thesis is drawn. Questions, at times, can result in just comments that indicate listener involvement.