38 Maintenance and service
6.4 Metrological check / electrical safety
Only persons with the appropriate technical knowledge may perform this test. Interna-
tional and country-specific regulations must be complied with. ATMOS recommends:
Work should be carried out by an authorized ATMOS service partner.
When the test is completed make sure the following is available:
•
Test report with the target and actual value of all parameters as well as the error
limits
•
Seal of approval with information on the testing organization and the date for the
next check
At least the following will be tested within the metrological check:
•
Visual check, wear parts will be replaced
•
Function check
•
Patient probe and patient communication test
•
Disturbing noise, cross-talk, distortion test
•
Pressing force of the headphones
•
Frequency accuracy of the test tone
•
Total harmonic distortion (THD) of the air conduction
•
Tone level attenuation
•
Deviation of the sound pressure level tone and noise masking per setting frequency
air conduction
•
Total harmonic distortion of the bone conduction
•
Deviation of the force level bone conduction per setting frequency
•
Speech sound level measurement
•
Measurement of the frequency response for the speech reproduction via the head-
phones
•
Deviation of the tone sound level / speech in free field
•
Repeat test of the electrical safety acc. to IEC 62353