AT235 Additional Information Page 23
When the AGC (automatic gain control) checkbox is marked, the size of the ear canal is taken into
account for adjusting the stimulus level. Without compensation, the intensity level will increase as
the size of the ear canal decreases. Note that current tympanometry standards do not yet describe
how AGC should be applied. We recommend that AGC is used when testing infant ears, as,
theoretically, with ear canal volumes smaller than 0.2 ml, the stimulus level can be increased by 20
dB or more. The AGC is applied for both the ipsilateral and contralateral insert.
The table shows which reflex latency will be tested. Selecting the bottom row enables the addition
of a new Latency stimulus. Hold the button while selecting with the wheel which
stimulus to add. Note that rotating down gives ipsi lateral stimuli and rotating up gives contra lateral
stimuli. The table below shows which stimuli are available depending on the probe tone frequency
and which side you are measuring. NB stands for narrow band noise. LP stands for low pass
filtered noise which has a spectrum from 400 Hz up to 1600 Hz. HP stands for high pass filtered
noise which has a spectrum from 1600 Hz up to 12 kHz. WBN stands for wideband noise which
has a spectrum from 400 Hz up to 12 kHz.
When a reflex Latency is selected from the table, hold the button while rotating
the wheel for changing the stimulus type. Press the button in order to remove
the reflex sequence from the table.