FEATURE ARTICLE
The Design and Function of Cochlear Implants
Fusing medicine, neural science and engineering, these devices transform human speech into an electrical code that deafened ears can understand
Michael Dorman, Blake Wilson
An Elusive Pleasure
Scott and others like him who achieve high levels of word
recognition report that speech sounds natural and clear through the
implant. No patient (in our experience) has described music in this fashion.
This result points to a fundamental difference in the requirements
for speech understanding and music appreciation. Implants do not
need to reproduce the precise frequencies of speech to preserve
meaning. But precision is absolutely essential for music. An octave,
for example, cannot be stretched in the way that frequency
components for speech can be stretched. If the A above A440 is to be
heard as an octave higher, then an implant must convey a signal at
880 hertz. A small error yields a different note. Although we have
had a small amount of success using octave intervals to tune signal
processors for a few patients with extensive musical backgrounds,
creating pleasant—or even tolerable—musical experiences
for the majority of cochlear–implant patients remains an
elusive goal.
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