Interesting point. I am certainly an introvert - I hate the telephone and love e-mail. I auxiliary pioneered for nearly 2 years, and it was an emotionally exhausting experience which made my shyness much worse, and I suffered depression for around ten years. However, I never had a problem with public speaking - I could give a public talk (in English or Portuguese) without breaking a sweat whereas even many extroverts seemed to find that difficult. Maybe because most of the work goes into preparation? Dunno.