One method is to place the speaker on one or more tracks.
With one copy use the ExpressFX Chorus. Start with Fast Heavy Chorus
Size 2, Rate around 6 and around 20% depth.
Add Pitch Shift FX adjust each copy track either lower or higher depending on
the speaker's voice and click preserve duration box.
Adjust the "chorus" of tones volume down so you can still
understand the main speaker's track.