Cochlear SPrint Sound Processor Información técnica descargar pdf (Pagina 25)

CLINICAL GUIDANCE | SECTION ONE

required programming changes. Note: Nucleus 24 system implant recipients

may upgrade to the CP810 or Freedom processor regardless of their current

sound processor type.

1.7.3 Nucleus

22 System

The Nucleus 22 System does not include a telemetry function. For recipients

using the CI22M implant (i.e. with the Spectra, ESPrit

™

22, ESPrit 3G for

Nucleus 22 or Freedom

™

for Nucleus 22 sound processors) it is likely that the

Stimulus Level or ESPrit Stimulus Level (ESL) amplitude mapping scale is used.

This Stimulus Level and ESL scales use changes to both current amplitude

(Current Level) and pulse width to control loudness. First the pulse width

is held ﬁxed and the current is increased, then the current is held constant

and the pulse width is increased to deliver increased charge. The range of

clinical programming units for Stimulus Level is 1 – 239. The range for ESL is

1 – 255. When using Stimulus Level or ESPrit Stimulus Level MAPping, it is not

possible to diagnose behaviourally that the implant is ‘out of compliance’. This

is because the charge per phase (or loudness) is increased by increasing the

pulse width rather than through increasing the current amplitude for a large

portion of the scale, i.e. for Stimulus Levels between 66 and 228, and for ESL

between 128 and 223. As a result the recipient will perceive loudness growth

as the Stimulus Level increases even though the implant is ‘out of compliance’.

To diagnose ‘out of compliance’ with a Stimulus Level or ESPrit Stimulus Level

MAP, it is necessary to change to Current Level MAPping, using a pulse width

that is narrow enough to allow presentation of Current Levels up to 190

Current Level. If the recipient reports that the loudness continues to grow up to

this level, the implant is not ‘out of compliance’.

1.8 POWER OPTIMIZATION

It is important to optimize a recipient’s power level to ensure that all channels

are in compliance, to allow the widest range of MAP parameters to be used

for a given recipient, and to maximize sound processor battery life.The CP810/

Freedom sound processors (CI500 series, Nucleus

Freedom

™

, and Nucleus 24

implant types) and Custom Sound software can automatically optimize the

power level used by the processors to power the implant. Power optimization

works by characterizing how much power is consumed by the implant in worst

case conditions. This assumes noise levels equivalent to a noisy room (> 65

dB SPL). It does this for each of the recipient’s MAPs. Then the power level for

each MAP is optimized to the minimum possible, such that the implant is in

compliance at all times.

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