D-0114042-D – 2020/03
Sera™ - Additional Information Page 21
Electrode impedance check with Sera
TM
Figure 14: Impedance check
After attaching the electrodes and cables to the baby, it is
essential to check if the impedances are acceptable for testing.
Typically, the impedance of each electrode site should be as low
as possible, however testing is still possible with higher
impedances.
After pressing start, the system will automatically detect the
electrode impedance and an indication of the impedance
acceptability will be displayed on the infant picture in either green
or amber (Figure 14). A green dot indicates an impedance
between 0 and 50kΩ (Acceptable). An amber dot indicates the
impedance is above 50kΩ (Poor).
Electrode impedance is monitored only before and after testing.
Therefore, during testing only the cable color indicators are
shown on the infant picture. Just before a recording stops the
electrode impedance is measured and saved with the session.
Historic sessions show these saved electrode impedances.
If an electrode falls off or becomes disconnected during testing,
the Preamp will detect an abnormal input and a message will be
displayed to ask the user to “Reconnect electrode”. A warning
tone can also be heard when an electrode is disconnected.
Please note that when it is not possible to get low enough
impedances (> 50kΩ), the software will not allow you to start a
measurement.
Transducer information area in Sera
TM
On the preparation screen of Sera
TM
, the type of transducer to be used
is displayed next to the baby’s head.
The transducer is automatically detected when connected to the
preamplifier. Because the transducer contains its own calibration data it
can be freely connected to any Sera
TM
The following transducers can be used for Automated ABR testing:
• IP30 insert earphones with ear tips
• IP30 insert earphones with EarCups
• OWA probe
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