Product Manual

20 Routine Maintenance Welch Allyn AM282 Audiometer
2. Conduct similar tests with several young adults on whom subsequent retests may be
made. Record the results on the audiogram forms.
3. File these audiogram forms where they will be readily available for comparison with
future results.
If the AM282 Audiometer is to be used to monitor employee thresholds as part of an
industrial Hearing Conservation Program, this “biological listening check” must be done at
the beginning of each day the audiometer is to be used (per CFR 1910.95 Occupational
Noise Exposure, March 8, 1983).
Since individual thresholds can shift up or down as much as 5 dB from one day to the
next, variation within this range may be considered acceptable. Variations that exceed this
range, however, are likely to reveal problems that require attention. The routine
maintenance checks described in this chapter may suggest the source and solution to the
problem. If they do not, the instrument should receive technical service by a certified
technician before further use.
Earphone cords
With extended use, earphone cords tend to fray internally at the junctions of both
earphone and audiometer connectors. This fraying will ultimately 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 to 1000 or 2000 Hz.
2. Set the HL knob at a comfortable audible level and use a Steady Tone type.
3. Press the Present bar 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.
Hum and random noise
With the instrument set on 1000 Hz, move the HL knob from 0 to 60 dB and listen for low-
frequency hum and random noise (hiss or low rushing sound) at all attenuator levels.
Some audible random noise at levels above 60 dB is permissible. Below 60 dB, however,
only the signal should be audible. Any of these noises can be confused with the signal by
naive subjects and affect the accuracy of the audiogram. Schedule the audiometer for
immediate service if any audible hum or noise is detected for clarity.
Distortion and frequency shift
This check can be best made by listening to the output of the AM282 Audiometer through
the earphones while presenting all 11 frequencies at a loud, but not uncomfortable, level
(70 to 80 dB HL for normal ears.)
Listen for rattling, rasping or distortion in the tones presented. Listen also to verify that
signal frequencies change appropriately when the frequency selector is moved to a new
position. If distortion is heard in one earphone but not in the other, the chances are high
that the earphones are at fault and should be replaced. In any case, the audiometer should
be scheduled for immediate maintenance.