Service Manual MA 42
D-0125965 Rev. D
15
18/05/2022
Service and Calibration
This chapter contains calibration standards for the MA 42, Included here is an illustrated
guide of how to calibrate the transducer types used with MA 42.
4.1 Service, Adjustment and Repair
MA 42 can be serviced, adjusted and repaired without losing the validity of the CE-
marking, provided the measuring equipment fulfills the below demands, the adjustment
procedures are followed and staff have the necessary qualifications as approved by
MAICO.
Before any attempt is made to calibrate MA 42, it must have been powered on for 3-5
minutes in an ambient temperature that is both stable and comfortable.
4.1.1 Hardware Calibration
The hardware calibration of MA 42 is typically performed during the production of the
device and therefore does not require adjustment in the field.
4.1.2 Equipment for the Calibration
To ensure proper calibration of audiometric equipment, test instruments must be reliable,
stable and their calibration certified. The minimum requirements for calibration equipment are:
- Type 1 sound level meter
– Octave band filter set (1/3 octave, range of minimum
125 Hz to 16000 Hz) must meet Type 1 sound level meter (ANSI S1.4). The
sensitivity of the Sound Level Meters must be checked before use with a sound
level calibrator.
- Piston phone or sound level calibrator
- Acoustic couplers:
- NBS
–9A (6cc) ANSI/ASA S3.7, or IEC 60318-3, Electroacoustics – Simulators
of human head and ear
– Part 3: Acoustic coupler for the calibration of supra-
aural earphones used in audiometry.
- IEC 60318-5, Electroacoustics
– Simulators of human head and ear - Part 5:
2 cm³ coupler for the measurement of hearing aids and earphones coupled to
the ear by means of ear inserts
- Calibration reports/sheets to keep track of the measuring results and ensure that
the audiometer meets the requirements.
4.1.3 Calibration of Test Equipment
All test equipment used for the calibration of audiometers is to be calibrated annually.
Calibration of all test equipment is to be performed by a laboratory which is traceable to
the National Institute of Standards and Technology (NIST) or equivalent. Test equipment
calibration documents are to be kept on file.
