Anonymous wrote:It's casually referred to as "Locust Valley lockjaw" - see:
http://en.wikipedia.org/wiki/Locust_Valley_lockjaw
Her speech is slow and deliberate on the White House tour but if you listen to the recordings of her interviews with Arthur Schlesinger (published as "Jacqueline Kennedy: Historic Conversations on Life with John F. Kennedy") you can hear what she sounded like in a more casual setting -- less deliberate, at times (but not always) less whispery, but still with an accent.
I doubt she was faking it -- she didn't have to.