Welch Allyn AM 232, Руководство по эксплуатации

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Routine test administration
HL control (F3)
The HL control increases or decreases the presented intensity in 5 dB HL steps with
the currently available intensity displayed on the LCD. Rotating the
Control knob
clockwise increases the intensity; counterclockwise decreases intensity. When the
maximum or minimum available intensity is reached for any frequency, the display will
flash to alert you that the available range can not be exceeded.
Range Extension pushbutton (F2)
This control allows the operator to present tones of up to 10 dB above the standard
maximum HL at any frequency. It will only function when the intensity is set within 10
dB below the maximum standard intensity at any frequency. This feature requires an
extra step to access or use the highest available intensities, requiring the operator to
make note of those individuals requiring testing at these levels. It also prevents
accidental presentation of the highest intensities to normal subjects, and it alerts the
operator to present the stimulus for only brief periods of time.
To enable the range extension feature, press the button labeled +10 dB . Note that a
“+” sign appears on the LCD. To disable the feature, either press the button a second
time, reduce the intensity (with the
HL control knob) to 20 dB below the standard
maximum HL or change any other parameter (Frequency or Routing).
Tone Type Selector (F9)
This control allows you to choose the type of tone presented to the test subject. It
can be set on
steady , pulsed (2.5 pulses per second) or FM (warble tone).
Pulsed tones and warble tones are often used with difficult to test subjects, such as
children and hard of hearing individuals, because they hold the subject’s attention
better than the steady tone.