Cochlear SPrint Sound Processor Información técnica descargar pdf (Pagina 6)

SECTION ONE | CLINICAL GUIDANCE

• Current Level (CL) – the amount of electrical current delivered to the

implant recipient expressed in clinical programming units from 1 – 255.

Current Levels represent the amplitude of the biphasic current pulse

in microamperes (µA) on a log scale similar to dB (5.7 CL = 1 dB). The

amplitude range of the cochlear implant stimulator is 10 µA - 1.75 mA (see

Figure 1 on page 3).

• Pulse Width (PW) – the amount of time the stimulator delivers current,

expressed in microseconds (µs) per phase of the biphasic current pulse (see

Figure 1 on page 3).

• Charge per phase of the biphasic current pulse – the product of

current pulse amplitude and width: the greater the charge, the louder

the sound. Increasing the current amplitude or widening the pulse width

results in more charge and a louder sound.

When setting T- and C- levels, the clinician uses a ﬁxed pulse width and

increases the current amplitude using CLs from 1 – 255.

• T-level – Threshold Level – the lowest amount of stimulation in CL that

elicits a very soft, but consistent hearing sensation (the level at which a

recipient can just begin to hear sound).

T-level Assessment Procedures

Determine T-levels using an ascending approach because it gives a more

reliable measure of threshold. Starting at a low level (the software default is

80 CL, but you can decrease this if necessary), use your computer mouse to

increase CL by clicking on the up arrow next to the “set Ts” box in Custom

Sound. Alternatively, you can use the up arrow on your computer. By default,

the software increases the CL by 5 units; you may want a smaller step size

when you are near threshold. The software sends one stimulus at the speciﬁed

level, but you can increase the number of stimuli.

To conﬁrm that recipients consistently hear at T-level, you may ask them to

count the number of sounds they hear. To do this, increase the number of

stimuli (by increasing the number next to the blue ball) and present the stimuli

at the speciﬁed CL by pressing the blue ball icon. The recipient should correctly

count the number of stimuli. This is called a “counted T-level”. Typically,

counted T-levels are slightly higher than standard T-levels because the sound

must be a little louder in order to count the stimuli reliably.

It is not necessary to measure the T-level on all active channels. As part of

Custom Sound, the streamlined programming method selects 5 channels

(including channels 1 and 22) spaced along the array for T-level measurement.

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