Saturday, March 12, 2011

"Beat Deafness": Study on Inability to hear beats correctly

Science News

A man lost in musical time
Researchers document the first case of ‘beat deafness’
By Bruce Bower
March 26th, 2011; Vol.179 #7 (p. 9)

The Go-Go’s had a 1982 hit record with “We Got the Beat,” but a 23-year-old man named Mathieu never got their message. Researchers have identified Mathieu as the first documented case of beat deafness, a condition in which a person can’t feel music’s beat or move in time to it.

Mathieu flails in a time zone of his own when bouncing up and down to a melody, unlike people who don’t dance particularly well but generally move in sync with a musical beat, according to a team led by psychologists Jessica Phillips-Silver and Isabelle Peretz, both of the University of Montreal. What’s more, Mathieu usually fails to recognize when someone else dances out of sync to a tune, the researchers report in a paper that will appear in Neuropsychologia.

“We suspect that beat deafness is specific to music and is quite rare,” Phillips-Silver says. She and her colleagues plan to investigate whether Mathieu takes an offbeat approach to nonmusical activities, such as conversational turn-taking and adjusting one’s gait to that of someone else.

Language lacks the periodic rhythms found in music, so it’s unlikely that Mathieu’s problem affects speech perception, remarks cognitive scientist Josh McDermott of New York University. If periodic sounds of all kinds confuse Mathieu, this problem may loom large when he confronts complex musical beats, McDermott suggests.

Mathieu does much better — although still with room for improvement — at bouncing in sync to a metronome’s periodic tone, indicating that he has a timing problem specific to music, Phillips-Silver says. Mathieu sings in tune and recognizes familiar melodies, so musical pitch doesn’t elude him.

Hearing and motor areas of Mathieu’s brain appear to be healthy, the researchers add.

They hypothesize that the young man’s beat deafness arises from disconnects in a widespread brain network involved in musical beat, rhythm and meter. Babies recognize simple musical beats within days of birth, possibly reflecting the operation of an inborn neural timekeeper (SN: 8/14/10, p. 18).

With further research, beat deafness may join tone deafness as a music-specific disorder. Researchers regard tone deafness an inherited disruption of a brain network that decodes musical pitch.

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