D-0128073-C – 2022/05
AT235 - Instructions for Use - US
Page 47
5.1 Calibration Properties
Calibrated Transducers: Contralateral
Earphone:
Telephonics TDH39/DD45 with a static force of 4.5N
±0.5N
Probe system:
Ipsilateral Earphone: is integrated in the probe system
Probe frequency transmitter and receiver and pressure
transducer is integrated in the probe system
Accuracy:
General
Generally, the instrument is made and calibrated to be
within and better than the tolerances required in the
specified standards:
Reflex Frequencies:
±1%
Contralateral Reflex
and Audiometer Tone
Levels:
3 dB for 250 to 4000Hz and 5 dB for 6000 to 8000Hz
Ipsilateral Reflex Tone
Levels:
5 dB for 500 to 2000Hz and +5/-10 dB for 3000 to
4000Hz
Pressure
measurement:
Compliance
measurement:
5% or 10 daPa, whichever is greater
5% or 0.1 ml, whichever is greater
Stimulus Presentation
Control:
Reflexes:
ON-
OFF ratio ≥ 70 dB
Rise time = 20 ms
Fall time = 20 ms
A weighted SPL in Off = 31 dB
Impedance Calibration Properties
Probe tone
Frequencies:
226 Hz 1%, 678 Hz 1%, 800 Hz 1%, 1000 Hz 1%
Level:
85 dB SPL 1.5 dB measured in an IEC 60318-5
acoustic coupler. The level is constant for all volumes in
the measurement range.
Distortion:
Max 1% THD
Compliance
Range:
0.1 to 8.0 ml
Temperature
dependence:
-0.003 ml/C
Pressure dependence: -0.00020 ml/daPa
Reflex sensitivity:
Reflex artifact level:
0.001 ml is the lowest detectable volume change
≥95 dB SPL (measured in the 711 coupler, 0.2 ml, 0.5 ml,
2.0 ml & 5.0 ml hardwalled cavities).
Temporal reflex
characteristics:
(IEC60645-5 clause
5.1.6)
Initial latency = 35 ms (5 ms)
Rise time = 42 ms (5 ms)
Terminal latency = 23 ms (5 ms)
Fall time = 44 ms (5 ms)
Overshoot = max. 1%
Undershoot = max. 1%
Pressure
Range:
Values between -600 to +400 daPa can be selected in
the setup.
Safety limits:
-750 daPa and +550 daPa, 50 daPa
Barometric pressure
The barometer
pressure chances
influence on the
impedance
measurement in the
specified range (97300
– 105300 Pascal).
Admittance can vary inside: ± 4%
The pressure accuracy is: ±10 daPa or 10%, whichever
is greater.
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