Do your friends cover their ears when you sing along with the
radio? Does the choir director ask you to lip-sync? If you're one of the unlucky people who is tone-deaf, it turns out your brain may have a wiring problem. That's what new research suggests.
People who are tone-deaf can't detect differences in musical
pitch but usually have normal hearing and speech. Tone-deafness
runs in families, and estimates of how many people have the problem
range from 4% to 17%.
In the small study done in Boston, brain scans showed there was
a difference in a particular brain circuit between those who were
tone-deaf and those who weren't.
Among the tone-deaf, researchers discovered there were fewer connections between two areas of the brain that perceive and produce sounds.
The study's lead author, Psyche Loui, likened the connection to
a highway between two islands in the brain.
In tone-deaf people, "there's less traffic on the highway," said
Loui, who studies music and the brain at Harvard Medical School and
is also a musician.
How the study was done
Loui and her colleagues took brain scans of 20 people, half of
them tone-deaf. Those who were tone-deaf had fewer nerve fibres
between the frontal and temporal regions of the brain, or in some
cases the fibres couldn't be detected at all. The researchers reported their the Journal of Neuroscience.
"It's a new piece in our understanding of tone-deafness and the
processes that are involved in the perception of pitch in general,"
said Nina Kraus of North-western University, who wasn't involved in
Loui said the brain connection they examined was long known to
be involved in language. "Now that we know which brain pathways to
train," she said, there may be ways to help people with
tone-deafness, and perhaps those with other language disorders. – (Sapa, August 2009)