Real Ear Measurements And Maintainance; Performing Insitu Measurements; Calibration Of The Probe Tube - Siemens Unity 2 Mode D'emploi

5.5 Real Ear Measurements and maintainance

Unity 2 is equipped with a bilateral Insitu Headset, each side providing a probe microphone port, an inbuilt reference
microphone and an inbuilt receiver for measuring RECD (Real Ear to Coupler Difference). The probe microphones can be
moved easily along the ear hanger to be fixed as close to the ear as possible.
The probe tube must be kept clean to ensure exact measurement results. Cerumen must be removed
from the probe tube by means of a cleaning wire before measurement. For hygienic reasons, a fresh,
new probe tube must be used for each new patient.

5.5.1 Performing insitu measurements

Insitu measurements allow to individually fit a hearing aid
to the patients ear and take the individual ear canal size
and length into account. A small probe tube (A) is inserted
into the ear canal to be able to measure the sound pres-
sure level right in front of the eardrum. These measure-
ments are performed usually in free field or alternatively
by using insert earphones to provide a signal to the ear.
A reference microphone (E), which is located in the probe
(C) is equalizing the signal spectra and controls the level.
The probe tube (A) is connected to the microphone port
(B) of the probe (C) and will be inserted into the ear canal.
To prevent slipping out of the ear canal the probe tube
can be fixed with the fixation holder (D).
It is expected that the user has been properly trained for
performig insitu measurements in the ear canal.

5.5.2 Calibration of the probe tube

Attach the probe tube (A) to the microphone port (B) of
the Insitu Headset and hold its open end (F) in front of the
probe reference microphone (E). For that purpose fixate
the Probe Tube end (A) between two of the three catches
(G) next to the probe reference microphone (E), as it is
shown in the pictures.
In the PC Probe Software Program Menu, start the Unity
Tube Calibration Screen from the tool bar icon and follow
the instructions which are given in the software user
interface to perform the calibration procedure. Select the
side to be calibrated and press the "Calibrate" button to
start the procedure.
During the measurement a sweeped pure tone is heard
from the speaker and a curve is drawn in the measure-
ment window of the calibration dialogue. The right side
curve will be shown in red color, and the left side curve
in blue color. The curve should look smooth as shown
in the figure above and should stay within the white col-
ored area, plus/minus 10 dB around 80 dB SPL.
44 Unity 2 – User Instruction Manual
A
E C
B
D
G
F
E