Editor: OK, that's not quite accurate, but I bet it got your
An MIT researcher has designed a cochlear implant (CI) that does
virtually all of its processing in analog mode rather than digital. What
this means is that it uses considerably less power than standard CIs
that process in digital mode, and it appears to perform every bit as
well as the digital versions.
Here are a few excerpts from the New York Times story. For the
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COCHLEAR implants that restore some hearing to the profoundly deaf
have improved steadily over the past two decades. Although they are
called implants, however, these systems still lie mainly outside the
Most of the apparatus - including the microphone, processor and
batteries that transform speech into electrical signals passed on to
electrodes embedded in the cochlea - is still typically worn behind the
ear or in a shirt pocket. Researchers hope that one day the entire
apparatus, which is designed to stimulate the auditory nerves of people
who have lost or damaged cells in the cochlea, can be implanted in the
body. But before that goal can be reached, cochlear implants will need
to use far less power. Currently the batteries must be changed as often
as every four hours.
Now a researcher at the Massachusetts Institute of Technology has
devised a processor for cochlear implants that he says consumes only
about half a milliwatt, one-tenth of the processing power of current
devices. Such an acoustic processing chip, if proven to be effective,
might be suitable for next-generation cochlear devices that are fully
To save power, the new processor reverses the traditional pattern for
chips used in cochlear implants: it does most of the work with analog
circuits, not digital ones.
"Most people digitize the signal immediately as it comes from
the microphone," turning the information into bits that a digital
signal processor then handles, Dr. Sarpeshkar said. "We did the
opposite." The signal remains in analog form for most of the
processing, including filtering the sound, and is digitized only at the
last interface to drive the control circuitry of the electrodes.
The project was underwritten by industry sponsors, and Dr. Sarpeshkar
expects the chip to be available commercially within two years.
While Dr. Sarpeshkar's processor is based on analog circuits, it
includes digital outputs so that it can be used with other parts of the
system like the programming interface. Being able to reprogram the
processor is crucial because each patient has different auditory needs
that are translated into instructions to each electrode that stimulates
a nerve ending in the cochlea.