public speaker       
noun [ C ] uk/ˌpʌb.lɪk ˈspiː.kər/ us/ˌpʌb.lɪk ˈspiː.kɚ/
 公开演说人,演讲者,演说家
someone who speaks on a subject to an audience
  He is a gifted public speaker who can rouse a crowd with his rhetorical skills. 他是一个颇有天赋的演说人,能用修辞技巧唤起听众的共鸣。 
 - More examples
 - I don't consider myself a great public speaker, but I can deliver a message.
 - Drama classes help children to become better public speakers.
 - He was in demand as a public speaker at conferences and formal dinners.
 - She was a former talk show host who made a living as a public speaker.