User guide
60
•
A
N EDUCATOR’S GUIDE
d. Turn on the sound processor to the
program location recommended by the
cochlear implant audiologist for FM use.
e. If necessary, synchronize the transmitter and
receiver so that they are on the same FM
channel.
f.
Reduce the microphone sensitivity of the
sound processor to z
ero.This disab
les the
sound processor microphone.
• Test the child’
s speech recognition (again,
auditory-only) with speech presented
through the FM transmitter microphone.
• Perf
ormance should be similar between
the sound processor-only and FM-only
conditions.
-
If not,
the gain on the FM receiver
may need to be increased. In some
cases, however, too much gain can
cause distor
tion of the signal,
resulting
in degraded performance.
- Testing should continue, therefore,
until the optimal gain setting is f
ound
for the individual child.
g. Now, turn off the sound processor (and FM
receiv
er if po
w
ered separately). It is best
that the FM receiver is not removed while
the sound processor is still turned on. Turn
off
the FM tr
ansmitter as well.
h. Turn on the sound processor, and return the
microphone sensitivity setting to the level
used by the child for everyday listening.
i. With the teacher at typical classroom
distance, the audiologist can measure the
sound level at the student’s ear. Then, a
noise signal, which is 5dB less than the
speech signal, can be placed at 90 degrees to
the student’s cochlear implant side, about 3
feet away.
j. Obtain the speech recognition score for the
speech in noise condition (auditory only,
sound processor alone).
k. Finally, re-activate the FM system and repeat
testing in noise. For the Spectra, SPrint
™
,
and ESPr
it
™
ser
ies sound processors,
microphone sensitivity setting typicall
y needs
to be reduced slightl
y below the ever
yday
use setting in order to allow the FM signal to
be predominant, yet also allo
w the child to
monitor his/her own voice and hear his/her
classmates. With the Freedom sound
processor
, a mix r
atio is applied
automatically, which reduces the level of the
sound processor microphone when an
accessor
y is in use
. This mix ratio may need
to be modified by the cochlear implant
audiologist.
When the FM system is not in use, the sound
processor microphone sensitivity setting should be
retur
ned to the lev
el used f
or everyday listening,
or, for the Freedom sound processor the setting
should be returned to the “M” setting (see
processor user guide).