Welch Allyn AM 232 Manual Audiometer - User Manual - Manual (Page 29)

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Routine calibration check
It is good practice to make and file, at the start of each month’s testing, the audiogram
of a single subject or of a small group of subjects who are likely to be routinely
available for this purpose. Where physical arrangements permit, you can serve as a
subject.
This procedure should be performed when the Audiometer is installed, and be
performed each month thereafter. If the AM 232 Manual 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 Chapter 4, 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.