YOU R AG
124 Australian Geographic
MATTHAUS ATKINS; PARROT: FRIENDS OF THE WESTERN GROUND PARROT/Pezoporus wallicus flaviventris; IMPLANT: GETTY IMAGESWITH DR KARL KRUSZELNICKIH
EARING LOSS IS a major
disability. People have
been working on this for
centuries. Beethoven was totally
deaf, and would clench a pencil
between his teeth and press it
against the top of his piano to feel
the sound vibrations. But today we
have the Bionic Ear.
First, let’s look at the human
ear. The outer ear catches incom-
ing sound and directs it to the
eardrum. When you are listening
to the quietest sound you can
hear, the eardrum vibrates back
and forth by a distance equal to
the width of a hydrogen atom.
The eardrum then passes the
sound energy to three small
bones. The last of these pushes
on a membrane in the cochlea
(the inner ear). This membrane
sends sound energy into the liquid
inside the cochlea, which ends up
bending some of its 16,000 hair
cells. This generates electricity,
which is then sent via the auditory
nerve to the brain, which decodes
it into what we perceive as sound.
The Bionic Ear, partly devel-
oped in Australia, bypasses most
of this, and directly stimulates
the hair cells. The Bionic Ear has
three external parts, and two
internal parts.
Externally, it has a microphone
to pick up the sound. It also has a
sound processor – which is tuned
to detect and process human
speech, split it into channels and
send it to the third part, the
transmitter. The transmitter sits
behind the ear, and (a bit like
an electric toothbrush charger)
sends electricity to the receiver.
Inside the body, the receiver is
tethered to the bone. It picks up
the incoming signal through theskin, and sends it to the elec-
trodes. Finally, this array of up to
22 electrodes is inserted into the
cochlea, to directly stimulate the
hair cells. However, 22 electrodes
are far fewer than 16,000 hair
cells – so there is a loss of quality.
Even so, the modern cochlear
implant is surprisingly good.
Four countries were involved in
its development – Australia (under
Professor Graeme Clark), Austria,
the USA and France. Australia’s^
system is arguably the best. Today,
nearly a third of a million people
have cochlear implants.DR KARL is a prolifi c broadcaster,
author and University of Sydney physicist.
His new book, House of Karls, is
published by Pan Macmillan. Follow him
on Twitter at: twitter.com/DoctorKarlBIONIC EAR
NEED TO KNOW
Sound solution. More than
300,000 people around the world
now have cochlear implants.parks: Fitzgerald and Cape Arid, both
located near Esperance. In these parks,
there are just an estimated 140
individual birds remaining. It was these
disturbing statistics that motivated
volunteers, researchers and zookeepers
to create a captive breeding program,
in hopes of reviving the population.
After 45 days in quarantine, pairs of
the birds were released into the specially
designed aviaries to improve chances of
breeding. The breeding program is
funded mainly by donations from the
public or local businesses, grants by
the Department of Parks and Wildlife
(DPaW) and the zoo. Without the
captive breeding program, the western
ground parrot has a bleak future and
extinction caused by predation from
cats and foxes, and bushfires, is all but
inevitable. I work with the Friends of
the Western Ground Parrot, who
update and inform the general public
about the captive and wild populations.
With luck, their work, alongside Perth
Zoo and DPaW, will help save this
reclusive species from extinction.
MATTHAUS ATKINS, PERTH, WA
Parrot advocate. Perth-based reader
Matthaus Atkins (top) with a feathered friend.
The endangered western ground parrot (bottom).
Continued page 126