Volume 25 Issue 6 - March 2020

Michael Arnowitt
PHOTO COURTESY AMI
This affiliation has now been thoroughly documented. One of
the first researchers to link the two qualities was Adam Ockelford,
professor of music at England’s Roehampton University. Ockelford
found that an astonishing 40 percent of the blind children in his
studies had perfect pitch, (compared to only one in 10,000 people in
the regular population). This capacity springs from the youngsters’
lifelong reliance on auditory data to make sense of their world, says
Ockelford. Right from birth, the blind children paid more attention
to everyday noises than their sighted peers, and their attunement to
aural input reinforced their sensitivity to sound.
Ockelford’s theory of brain adaptation has been validated by a host
of evidence. The hearing of blind people surpasses that of the sighted
in in several modalities – they are better at discriminating between
different pitches, localizing sounds in space, and processing speech.
Their sense of touch is also more refined and they’re able to detect
finer-grained differences in the feel of objects.
The brain’s ability to compensate
for visual loss with enhanced
perception in other domains, is
adaptive, says McGill University’s
research associate Patrice Voss.
If you’re born without vision, or
you lose it early in life (when the
brain is especially mouldable),
the sight-processing centre in the
brain (the visual cortex), does not
receive input from the eyes. In
response to these absent signals,
the unused visual cortex gets
repurposed to process sound and touch stimuli instead.
Anatomical changes accompany this transformation. Imaging
studies have shown that the visual cortex is thicker than normal
among those who become blind early in life. This growth results from
new pathways springing from the sound and touch processing centres,
connecting these to the transformed visual cortex, reorganized to
interpret signals from the ears and skin.
While amplified sound sensitivity is more prominent amongst those
who are born blind or lose their sight early on, recent research shows
that the brain can adjust to vision loss at any stage in life. In one study,
mice were blinded temporarily after being shut in the dark. Afterwards,
researchers played tones of varying frequencies and measured the electrical
activity of cells in their brains’ sound processing centre (auditory
cortex). After just one week of light deprivation, these cells fired faster
and more powerfully, enabling the blind mice to detect quieter noises
and distinguish between pitches much better than the sighted mice.
Lead researcher Hey-Kyoung Lee, professor of neuroscience at
Baltimore’s Johns Hopkins University, attributes these impressive results
to strengthened connections between nerve cells carrying sound data
from the environment and those neurons which translate the signals
into conscious sound experience in the auditory cortex. These alterations
dial up the volume of external sound to increase its impact in the
brain, says Lee, who was surprised by the extent of the animals’ adaptation.
“We didn’t expect that level of change…(it) was pretty amazing.”
Violinist McCleary illustrates this plasticity of perception. She was
born with Leber’s congenital amaurosis, which damages the lightsensing
tissue in the eyes (the retina). But the fiddler makes up in
her hearing what she lacks in vision. She can detect noises at lower
volumes than her sighted friends. “If someone’s phone’s going off I
can hear that better than anyone else,” she says. McCleary also has
perfect pitch, which enables her to transform everyday noises, from a
beeping microwave to a fork hitting the table, into musical notes.
Those without sight depend on
An astonishing 40 percent of the
blind children in [Adam Ockelford’s]
studies had perfect pitch (compared
to only one in 10,000 people in the
regular population).
their acoustic acumen for survival,
says Voss. Their supranormal ability
to map space using sound helps
them get around. “They can’t rely
on sight to cross the street, and
need to (depend) ... on hearing to
recognize where traffic is,” he says.
The same faculty is also critical
for conversing, says registered
psychotherapist and neurologic
music therapist Amy Di Nino, who
runs her own business, ADD Music
Wellness (addmusicwellness.com), in Cambridge, Ontario. The timbre
of a particular voice identifies the speaker, while qualities such as
tone, rhythm, and pitch convey nuances of meaning. In the absence
of visual cues like body language, the blind draw on their listening
skills to intuit emotions in others – a rapid pace of speech can signal
anxiety, while loudness can convey anger, for example.
McCleary has always depended on her heightened hearing to make
sense of her world. The sound of a television in a familiar house guides
her to the living room, while a squeaky noise signals the washroom
door in her home. She’s also adept at extracting information from
voices, and readily picks up on her mother’s feelings. “If she freaks out
about something…she changes to a high voice,” says her daughter.
McCleary’s exceptional ear ultimately led to her career as a violinist.
The musician showed an affinity for tunes right from infancy. “(Music)
was a way in,” says her mother, a pianist and music professor, who
calmed her daughter with soothing Renaissance polyphony. “She was
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