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12 | Chapter 1
INTRODUCTION
With cochlear implants, electrical pulses can restore sound to deaf ears and provide speech perception
abilities to many deaf patients. The success of this technique is underscored by the large number of implanted
patients; more than 300,000 patients have received implants over the last three decades [Clark et al., 2013].
Cochlear implant components
Contemporary multichannel cochlear implants consist of external and internal parts (Figure 1). The external
part contains a microphone that receives the sound signal. The sound signal is then processed by a speech
processor. Briefly, the speech processor codes the auditory signal into separate frequency bands. The coded
signal is then sent through the skin to the internal receiver via a transmitter coil. The received signal is then
transmitted to the electrode array, which is located in the scala tympani of the cochlea. The currents exiting
the various electrode contacts stimulate the auditory nerve fibers in that portion of the cochlea.
History
The invention of an electrical capacitor called the Leyden jar in 1745 allowed electrical currents to be
stored. This innovation provided considerable inspiration for experiments with electrical currents. The first
description of the use of an electrical current to elicit hearing in deaf individuals dates back to 1748. In a
report from that period, Benjamin Wilson describes eliciting hearing in a deaf woman [Wilson B., 1752].
In 1800, Volta describes the sound evoked by the electrical stimulation of his own ear [Volta A., 1800]. The
unpleasantness of the sound prevented him from repeating the experiment.
Figure 1: The basic components of a cochlear implant. 1: The speech processor 2: the
microphone 3: the internal receiver 4: the electrode array in the cochlea
Introduction
With cochlear implants, electrical pulses can restore sound to deaf ears and provide speech
perception abilities to many deaf patients. The s ccess of this tec nique is und scored by he large
number of implanted patients; more than 300,000 patients have received implants over the last
three decades [Clark et al., 2013].
Cochlear i
la t components
Contemporary multichannel cochlear implants consist of external and internal parts (Figure 1). The
external part contains a microphone that receives the sound signal. The sound signal is then
processed by a s eech pro essor. Briefly, the peech pr c ssor cod s the auditory signal into
separate frequency bands. The coded signal is then sent through the skin to the internal receiver via
a transmitter coil. The received signal is then transmitted to the electrode array, which is located in
the scala tympani of the cochlea. The currents exiting the various electrode contacts stimulate the
auditory nerve fibers in that portion f th cochlea.
History
The invention of an electrical capacitor called the Leyden jar in 1745 allowed electrical currents to be
stored. This innovation provided considerable inspiration for experiments with electrical currents.
The first description of the use of an electrical current to elicit hearing in deaf individuals dates back
to 1748. In a report from that period, Benjamin Wilson describes eliciting hearing in a deaf woman
[Wilson B., 1752]. In 1800, Volta describes the sound evoked by the electrical stimulation of his own
ear [Volta A., 1800]. The unpleasantness of the sound prevented him from repeating the experiment.
Djourno and Eyries, who began their experimental work in the 1950s, are considered the pioneers in
the field of cochlear implants given their direct electrical stimulation of cranial nerve VIII [Eisen,
2003;Djourno and Eyries, 1957]. Based on their ideas, William House developed the first single
Figure 1:
The basic components of a cochlear implant. 1: The speech processor 2: the microphone 3: interna receiver 4: the electrode
array in the cochlea