Growing up, I never had an issue with public speeches like most of my peers did; I prepared my speech, got up and read it aloud for everyone to hear. I was never nervous, never thinking about the judgment people might place on my words (At the performance anyway; writing the speech, however, was a different animal altogether.) I simply spoke the words and asked for input after the fact.
Conversation, however, was a different animal altogether; if I wasn't anxious, I would stutter, I would not know what to say or how to respond to a question. For years I was a poor conversationalist, even with a high vocabulary and command of several subjects. Now, one may be asking, how could someone who is so good at speeches be a poor conversationalist?
The answer lies in the fundamental difference between a speech and a conversation. A speech is a prepared document, something where the presentation has been practiced and polished. In speeches, interruptions are rare and frowned upon, the signal to start is clearly given and the end dictated by the completion of the material presented. More often than not, the speaker has a decent command of the field of study presented in the speech as well. Finally, speeches are structured, and people on the autism spectrum do very well with structure.
Conversations, however, are random discourses of words, phrases and nonverbal cues, each having to be interpreted to see which idea is being conveyed. The opportunities to speak are often not seen, and interruptions are quite frequent. Trying to find that opportunity to speak becomes a chore in itself and the thought the autist may have had as well as whatever ideas the other people in the conversation may be conveying are often lost in the focus on that moment to speak. In short, a conversation is the worst way for an autist to convey an idea.
Unfortunately, most of the world operates in the conversation manner of speech, and this will be something that ultimately will take work on both sides to bridge. The autist can benefit from training in discerning nonverbal cues, and the neurotypical can benefit by verbally announcing when they have finished communicating their idea. Both sides, of course, benefit from allowing the other side more opportunities to speak in general.