otometrics Aurical Hit - 5.11 How to test the directional microphone; 6 Maintenance and Calibration; Maintenance; Repair

5.11 How to test the directional microphone
Directionality measurements as described in the hearing instrument test standards cannot be performed with regular desk-
top test chambers such as AURICALHIT. Such measurements require large anechoic chambers. Small test chambers always
exhibit acoustic reflections that obscure the true directional behavior of the hearing instrument.
However, in AURICALHIT you can make a functional test of the directional microphone in a hearing instrument. In this
test, the signal is first presented to the front of the hearing instrument and then to the back of the hearing instrument.
This is done automatically when you start a Directional Test. The signal used for this test is a flat spectrum Broad Band
Noise, band-pass filtered between 750 Hz and 5kHz, and presented at 70dBSPL.
The procedure
1. Position the hearing instrument as described in Traditional BTE hearing instruments ► 11, Thin-tube hearing instru-
ments ► 12 and ITE hearing instruments ► 13 depending on the type of hearing instrument.
2. In the field Directionality Adaptation in the OTOsuite HIT module, you can define the duration of the signal present-
ation before the actual measurement is made. This value accommodates any adaptational behavior of the hearing
instrument. Adaptive directionality often takes 10 to 15 seconds or more before the directionality of the hearing
instrument is fully efficient.
3. You can either combine the Directional Test with your standard test sequence by checking the sequence checkbox,
or run it separately by clicking the Start button.
The result
The Directional Test result is shown as a 1/3 octave curve of the difference between the measurement with noise presen-
ted from the main loudspeaker and the measurement with noise presented from the rear loudspeaker. The numerical dir-
ectionality result shown in the Measurements table indicates the average front/back difference in the measured
frequency range.
The Measurements table also includes the adaptation interval used in seconds.
6 Maintenance and Calibration
Warning• Under no circumstances disassemble AURICALHIT. Contact your supplier. Parts inside AURICAL HIT must
only be checked or serviced by authorized personnel. Calibration of the coupler microphone, and calibration of a new
reference or coupler microphone must only be performed by authorized personnel.
Maintenance
AURICALHIT requires no preventive maintenance except for cleaning and regular calibration of the reference microphone.
Repair
For any type of repair, please contact your supplier.
For the sake of safety and in order not to void the warranty, service and repair of electro-medical equipment should be car-
ried out only by the equipment manufacturer or by service personnel at authorized workshops. In case of any defects,
make a detailed description of the defect(s) and contact your supplier. Do not use a defective device.
Otometrics - AURICALHIT
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6 Maintenance and Calibration