Maico MB 11 Classic, Руководство по эксплуатации

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Operation Manual MB 11 Classic
8100498-4_OM_MB11_Classic_3.18_EN_16a.docx 64 01/16
12 Scientific Background Information
12.1 CE-Chirp Stimulus™
The stimulus for an automated ABR-newborn hearing screening should
generate auditory evoked brainstem responses with an amplitude as great
as possible at the level of 35 dB HL. High response amplitudes allow a fast
objective detection with high specificity and short measuring time.
Up to now in the field of hearing screening the standard click was used as
stimulus. The standard click is generated by delivering a short rectangular
electrical impulse to a transducer. This click generates a traveling wave along
the basilar membrane. The traveling wave runs from the basal part of the
cochlea along the basilar membrane to the tip of the cochlea (apex). Hereby
it excites each of the frequency areas of the cochlea starting with high
frequency part and ending with the low frequency part. The velocity of the
traveling wave is the greatest at the basal part of the cochlea and slows
exponentially towards the apex.
Figure 32 shows the delay of the travelling wave for reaching the various
frequency bands in the cochlea calculated from the cochlea model of de
Boer. The figure shows a delay shorter then 2 ms for the region from 10 kHz
to 1 kHz but a delay of 8 ms from the area of 1 kHz to 100 Hz. Due to the
resulting greater synchronization of excitation in the basal part of the
cochlea, only the higher frequency range contributes effectively to the click-
Figure 32