Free at last, free at last: Today is Martin Luther King Day. In honor of the birth of the Rev. Dr. Martin Luther King, Jr., who for some reason gets shortened into just three names, I am posting Mark Liberman's fascinating analysis of the phonetics of the famous "I Have a Dream" speech. He notes the sharp difference in the phonetics of the speaking styles of John F. Kennedy and King, for instance. It's a good read. From Language Log:

His timing is eloquent: he speeds up and slows down in a way that conveys how his sentences are put together. Every fluent speaker does this to some extent, and he does it abundantly and at the same time precisely. But within most phrases in this speech, his pitch is relatively level, almost as if he were chanting or singing rather than speaking.

In particular, his phrases often end with a sustained or slightly falling pitch, instead of the steeper relaxation to low pitch that English phrases usually have. Because the expected falls are missing, some of his sutained final syllables (e.g. "today" in the opening phrases) may sound to some people as if they go up. But listen carefully, and look at the pitch contours

[...]



Of course, King's individual phrases in this speech do have a melody -- though sometimes a subtle one -- that helps convey his message. And he varied the overall pitch range much more widely from section to section of the speech, as effective speakers since time immemorial have done to embody the ebb and flow of ideas and emotions. But there was something about the way that he chanted each phrase, like a song or a prayer, that commanded attention and memory.

[Link]