Otodynamics Otoport Advance, User Manual, Page: 16 / 296

Stim F2 (Hz) Stim F1 (F2/1.22) (Hz) DPOAE (2F1-F2) (Hz)
1000 820 640
1189 975 761
1414 1159 904
1682 1379 1076
2000 1640 1280
The pts/oct setting chosen depends on the requirements of the test. The
higher the resolution the more accurately the cochlea is assessed but the
test duration is longer.
There are two points to note when choosing pts/octave:
• DPOAEs are generated by regions of the cochlea, not individual points
on it. These regions are estimated to be about 1/3 octave wide, so
testing frequencies which are very close together results in repeatedly
testing a very similar cochlear region.
• DPOAEs have several sources. These sources can interfere so that
at a particular test frequency the resulting DPOAE can be enhanced
or reduced by the interference. Often referred to as fine structure, this
interference is very dependent on frequency so small changes in test
frequency can enhance or depress the OAE level recorded, with the
change having no bearing on cochlear health.
A 4 pts/oct test can effectively test all of the cochlea across the frequency
range selected. However individual DP points might be artificially
depressed by interference so testing at a higher resolution around a
frequency where DPOAE was low or absent can give a better interpretation
of cochlear health in that region.
Higher resolution testing is also useful when the DPOAE levels drop
dramatically at a particular frequency reflecting a change in the cochlea.
Higher resolution testing can help to define the frequency at which this
change occurs.
The Otoport allows the user to rapidly test a wide frequency range at 2 or
4 pts/oct or to ‘zoom’ in on a narrower frequency range and test at up to 16
pts/oct.
Introduction
CHAPTER ONE
Introduction
16