Maintenance; General Maintenance Procedures - Interacoustics AD629 Gebrauchsanweisung

AD629 Instructions for Use - EN

4 Maintenance

4.1 General maintenance procedures

It is recommended that routine check procedures are carried out weekly in full on all equipment in use.
Check 1-9 outlined below should be followed on the equipment on each day of use.
The purpose of routine checking is to ensure that the equipment is working properly, that its calibration
has not noticeably changed, and that its transducers and connections are free from any defect that might
adversely affect the test result. The checking procedures should be carried out with the audiometer set up
in its usual working situation. The most important elements in daily performance checks are the subjective
tests and these tests can only be successfully carried out by an operator with unimpaired and preferably
known good hearing. If a booth or separate test room is used, the equipment should be checked as
installed; an assistant may be required in order to carry out the procedures. The checks will then cover
the inter-connections between the audiometer and the equipment in the booth, and all connecting leads,
plugs, and socket connections at the junction box (sound room wall) should be examined as potential
sources of intermittency or incorrect connection. The ambient noise conditions during the tests should not
be substantially worse than those encountered when the equipment is in use.
1) Clean and examine the audiometer and all accessories.
2) Check earphone cushions, plugs, main leads and accessory leads for signs of wear or damage.
Damaged or badly worn parts should be replaced.
3) Switch on equipment and leave for the recommended warm-up time. Carry out any set-up
adjustments as specified. On battery-powered equipment, check battery state using the
manufacturer's specified method. Switch on equipment and leave for the recommended warm-up
time. If no warm-up period is quoted, allow 5 min for circuits to stabilize. Carry out any setting-up
adjustments as specified. On battery-powered equipment, check battery state.
4) Check that earphone and bone vibrator serial numbers are correct for use with the audiometer.
5) Check that audiometer output is approximately correct on both air and bone conduction by
conducting a simplified audiogram on a known test subject with known hearing; check for any
change.
6) Check at high level (for example hearing levels of 60 dB on air conduction and 40 dB on bone
conduction) on all appropriate functions (and on both earphones) at all frequencies used; listen for
proper functioning, absence of distortion, freedom from clicks, etc.
7) Check all earphones (including masking transducer) and the bone vibrator for absence of distortion
and intermittency; check plugs and leads for intermittency.
8) Check that all switch knobs are secure and that indicators work correctly.
9) Check that the subject's signal system operates correctly.
10) Listen at low levels for any sign of noise, hum, or unwanted sounds (break-through arising when a
signal is introduced in another channel) or for any change in tone quality as masking is introduced.
11) Check that attenuators do attenuate the signals over their full range and that attenuators which are
intended to be operated while a tone is being delivered are free from electrical or mechanical noise.
12) Check that controls operate silently and that no noise radiated from the audiometer is audible at the
subject's position.
13) Check subject communication speech circuits, if appropriate, applying procedures similar to those
used for pure-tone function.
14) Check tension of headset headband and bone vibrator headband. Ensure that swivel joints are free
to return without being excessively slack.
15) Check headbands and swivel joints on noise-excluding headsets for signs of wear strain or metal
fatigue.
The instrument had been designed to provide many years of reliable service, but annual calibration is
recommended due to possible impact on transducers.
We also required –recalibrating of the instrument; if something drastic happens to a part of it (e.g.
headset or bone conductor is dropped on a hard surface).
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