CHAPTER THIRTY-ONE
Technical specifications
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31.4
EN60645-3 conformance notes
These notes are provided in compliance with EN60645-3 “Electroacoustics
audiometric equipment - Part 3: test signals of short duration.”
(a) Types of short duration stimuli:
The Otoport TEOAE test uses short duration stimuli. During test setup a
‘rectangular stimulus’ is used. During data collection a ‘bipolar stimulus’ is used.
The rectangular is a unipolar pulse of 78uS length. The bipolar stimulus is 1
cycle of a triangle waveform of 240uS period. Both stimuli are low pass filtered
by a 10kHz anti-alias filter, which ‘rounds’ any ‘sharp edges’.
(b) Transducers and headband force:
The stimulus is delivered to the patient’s ear using a UGS or UGD Otodynamics
probe. The probe tip holds the probe ear piece in the ear canal, with no
headband or other retaining device required.
(c) Sound field system:
The sound field is generated by the probe sealed in the ear canal by its tip.
(d & e) Calibration cavity and measurement type:
For the purposes of EN60645-3 calibration was performed in an occluded ear
canal simulator conforming to IEC 60711 (Bruel and Kjear type 4157). The probe
was mounted in a DB2012 adaptor using an Otodynamics probe tip. The sound
ports of the probe were aligned with the 4157 reference plane. A UGD probe
was used for the calibration. Sound levels from the 4157 ear simulator were
measured in dB SPL peak-to-peak equivalent, as defined in EN60645-3.
(f) Signal levels:
The following conversion factors convert between the stimulus level reported on
the Otoport screen and the signal level in the IEC 60711 occluded ear simulator:
rectangular stimulus: -6.1dB
bipolar stimulus: -7.1dB
The following conversion factors convert between the signal level generated
in the ear simulator by the Otoport stimulus and the level that would be
generated by a ‘reference stimulus’ of the same peak to peak electrical drive.
(The ‘reference stimulus is a 100uS unipolar rectangular pulse, as defined in
EN60645-3.):
rectangular stimulus: +3.0dB
bipolar stimulus: +2.4dB
Technical specifications
Summary of Contents for Otoport Advance
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