At Nuance, whose headquarters are outside Boston, speech engineers try to anticipate all the different ways people might say yes, but they still get surprised. For example, designers found that Southerners had more trouble using the system than Northerners did, because when instructed to answer “yes” or “no” Southerners regularly added “ma’am” or “sir,” depending on the I.V.R.’s gender, and the computer wasn’t programmed to recognize that. Also, language isn’t static; the rules change. Researchers taught machines that when the pitch of a voice rises at the end of a sentence it usually means a question, only to have their work spoiled by the emergence of what linguists call “uptalk”—that Valley Girl way of making a declarative sentence sound like a question?—which is now ubiquitous across the United States.
John Seabrook, Hello, Hal, The New Yorker.