Welch Allyn AM 232, Руководство по эксплуатации

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Calibration
The biological listening check, or routine calibration check, should be performed at
least monthly. (See
Routine calibration check in Chapter 3).
The following checks should be made at periodic intervals, even if routine calibration
checks do not reveal any problems. These procedures presuppose normal hearing on
the part of the person doing the checking.
Earphone cords
With extended use, earphone cords tend to fray internally at the junctions of both
earphone and audiometer connectors. This fraying will ultimately either decrease the
signal level in the associated earphone or cause signals to be intermittent as the cord
is flexed.
To check for either condition:
1. Set the Audiometer frequency control ( F7 ) to 1000 or 2000 Hz.
2. Set the HL control ( F3 ) at a comfortable audible level.
3. Press the Present bar ( F4 ) and flex earphone cord next to plug at both ends,
listening for intermittent signal, abrupt changes in signal level, or a scratchy
sound superimposed over the signal that coincides with the flexing of the cord.
The presence of any of these three conditions signifies that the cord should be
replaced.
4. Repeat the test for the other earphone.