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Amusia is a deficit in musical memory, recognition, and in pitch processing that people can be born with or acquire through brain damage. Some people may think of themselves as being "tone-deaf", but most of these "bad" singers are just that. People with amusia are so unable to hear tones that they even struggle to differentiate between questions and statements when spoken. Language, like music, uses sound to convey meaning; be it a story, or simply an emotion. In fact, music and spoken language use many of the same structural elements: pitch, duration, intensity and melodic contour, to name a few. Melodic contour is the pattern in which pitch changes from high to low over time. This contouring of pitch is often used to express emotion in music. The emotional effect of contouring is appreciated across many cultures and across many age groups. In speech, melodic contour is created by intonation, which allows us to place emphasis upon certain words and distinguish the purpose of the sentence; e.g. whether it is a question, statement or command. These comparisons provide evidence for the overlap of brain areas and mechanisms that underlie speech and music processing. In addition, the storing of sound patterns in short-term memory is also overlapping for both language and music.

Scientists are reporting in the journal Science that they have identified specialized brain cells that help us understand what a speaker really means. These cells do this by keeping track of changes in the pitch of the voice. "We found that there were groups of neurons that were specialized and dedicated just for the processing of pitch," says Dr. Eddie Chang, a professor of neurological surgery at the University of California, San Francisco. Chang says these neurons allow the brain to detect "the melody of speech," or intonation, while other specialized brain cells identify vowels and consonants. "Intonation is about how we say things," Chang says. "It's important because we can change the meaning, even - without actually changing the words themselves." The identification of specialized cells that track intonation shows just how much importance the human brain assigns to hearing, says Nina Kraus, a neurobiologist who runs the Auditory Neuroscience Laboratory at Northwestern University. "Processing sound is one of the most complex jobs that we ask our brain to do," Kraus says. And it's a skill that some brains learn better than others, she says. Apparently, musicians, according to a study conducted by Kraus, are better than non-musicians at recognizing the subtle tonal changes found in Mandarin Chinese. On the other hand, recognizing intonation is a skill that's often impaired in people with autism, Kraus says. "A typically developing child will process those pitch contours very precisely," Kraus says. "But some kids on the autism spectrum don't. They understand the words you are saying, but they are not understanding how you mean it." The new study suggests that may be because the brain cells that usually keep track of pitch aren't working the way they should.

Elise Piazza, lead author and a postdoctoral research associate with the Princeton Neuroscience Institute, said, "Motherese contains exaggerated pitch contours and repetitive rhythms that help babies segment the complex noises around them into building blocks of language." She added that the speaking style also helps parents capture the attention of their babies and engage them emotionally.