Cochlear SPrint Sound Processor Información técnica descargar pdf (Pagina 33)

CLINICAL GUIDANCE | SECTION ONE

1.9.3 CIS/CIS (RE)

CIS (Continuous Interleaved Sampling) focuses on the temporal (timing)

properties of sound. It uses a relatively small number of channels (4, 6, 8 or 12)

in comparison to SPEAK and stimulates them at a high per channel rate. Higher

stimulation rates better represent the rapid timing events in sound compared

to lower rates. By default, the software chooses a ﬁxed set of 12 channels and

a 900 pps channel rate (TSR = 10800 pps). The clinician may choose other

rates (900, 1800, 2,400 or 3500 pps) and different numbers of channels (4,

6 or 8), with the stipulation that the maximum TSR not exceed 14, 400 pps

for Nucleus

24 implants or 28,000 pps for Freedom implants. The TSR is

the per channel rate multiplied by the number of channels. Custom Sound

™

provides a list of available rates and number of channels based upon the type

of implant used by the recipient. The CIS (RE) rate of 3500 pps is speciﬁc to

the Freedom

™

cochlear implant. Although the software selects speciﬁc default

channel sets, the clinician can modify these. CIS stimulates the same ﬁxed set

of channels during each stimulation cycle regardless of any changes in spectral

(frequency) information. CIS divides the acoustic bandwidth (188 – 7938 Hz)

by the number of channels (4 – 12) used. This determines the bandwidth for

each channel. The software automatically assigns a bandwidth to each ﬁxed

channel in a tonotopic way (i.e., the most basal channel receives the highest

frequencies and the most apical channel the lowest frequencies). During each

stimulation cycle, CIS determines the amount of energy in each band and

delivers the appropriate electrical current. The amount of current (between

T- and C-level) sent to the channels is directly proportional to the amount

of energy in each band. CIS cannot currently be used with the CP810 Sound

Processor unless accessed as a regional option in the Custom Sound software.

Figure 8 :

Electrodogram of

the English word

‘choice’ using the

CIS strategy

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 77 78

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Cochlear SPrint Sound Processor Información técnica Pagina 33