ROBERT SIEGEL, HOST:
Communication is about more than just the words we say. It's about how we say them.
(SOUNDBITE OF TV SHOW, "THE TONIGHT SHOW STARRING JOHNNY CARSON")
ED MCMAHON: Here's Johnny.
SIEGEL: That's how Ed McMahon used to introduce Johnny Carson on "The Tonight Show." And here's Jack Nicholson's version from "The Shining."
(SOUNDBITE OF FILM, "THE SHINING")
JACK NICHOLSON: (As Jack Torrance) Here's Johnny.
SHELLEY DUVALL: (As Wendy Torrance, screaming).
SIEGEL: Not quite the same message. Well, now scientists have identified a group of brain cells that help listeners figure out what a speaker's words actually mean. NPR's Jon Hamilton reports.
JON HAMILTON, BYLINE: When we speak, we do a lot more than produce a stream of vowels and consonants. Our voices rise and fall in a way that adds meaning to every sentence.
EDDIE CHANG: Some people think about this as sort of the melody of speech.
HAMILTON: Eddie Chang is a neurosurgeon at the University of California, San Francisco. He's been studying how the brain keeps track of this melody or intonation.
CHANG: Intonation is about how we say things. It's important because we can actually change the meaning even without actually changing the words themselves.
HAMILTON: It's the difference between really and really. To learn more, Chang's lab monitored the brain activity of ten people as they listened to speech produced by a computer.
CHANG: What we did was change where the intonation contour or where the pitch changes were happening in each of those sentences.
HAMILTON: So the volunteers might hear a statement like...
COMPUTER-GENERATED VOICE: Movies demand minimal energy.
HAMILTON: ...Or a question like...
COMPUTER-GENERATED VOICE: Movies demand minimal energy?
HAMILTON: And Chang says certain brain cells were responding only to intonation.
CHANG: We found that there were groups of neurons that were actually specialized and dedicated just for the processing of pitch.
HAMILTON: The cells didn't care whether they heard a high female voice or a low male voice. Chang says it was the pattern of pitch changes that mattered.
CHANG: To people like musicians, this is not a surprise because you can take a melody and shift all of its notes higher or lower, but it's still recognizable.
HAMILTON: Chang says the cells that recognize intonation work with other specialized cells to help us understand what someone is trying to say. Nina Kraus, a neurobiologist at Northwestern University, says it's remarkable.
NINA KRAUS: Processing sound is one of the most complex jobs that we ask our brain to do.
HAMILTON: And Kraus says it's something some brains learn better than others. She found that out when she studied whether musicians were better at recognizing the subtle tonal changes found in Mandarin Chinese.
KRAUS: The English-speaking musicians were able to process with high precision those contours. And the non-musicians didn't.
HAMILTON: On the other hand, Kraus says, recognizing intonation is a skill that's often impaired in people with autism.
KRAUS: A typically developing child will process those pitch contours very precisely. But some kids on the autism spectrum don't. You know, they understand the words that you're saying, but they are not understanding how you mean it.
HAMILTON: Perhaps because the brain cells that usually keep track of pitch aren't working the way they should. The new research appears in the journal Science. Jon Hamilton, NPR News.
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