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Microphone Sensitivity
The sensitivity of a microphone is determined by the output voltage it produces
for a defined sound source.
Microphones are manufactured with numerous sensitivity levels and operate
within a specified tolerance. Different microphones of the same model may
therefore give slight differences in readings when used on the same sound
meter. To allow for this all Sonus meters have been designed to accommodate
any variations in the tolerance of the supplied microphone up to ±3dB.
Sonus models L, I and B have been designed for microphones with a sensitivity
of 25mV/Pa and model E for microphones with a sensitivity of 50mV/Pa.
Great care must be taken to ensure the microphone and sound meter
sensitivities match otherwise incorrect readings will occur.
Certifiable Calibration
The calibration process includes the microphone, pre-amplifier and sound level
meter. Any change in this measurement chain will require a new certifiable
calibration.
Castle Group Ltd offers a complete calibration service offering either a full UKAS
calibration or a standard NPL traceable calibration which can be supplied with
or without a test report.
It is recommended that your sound meter instrumentation is calibrated annually
to ensure your measuring equipment is completely accurate and fully compliant.
Removal of Microphone
The microphone can be fitted to the pre-amplifier by screwing the microphone in
a clockwise direction ensuring that the pre-amplifier spring pin is located
centrally in the microphone. To remove the microphone unscrew in an anti-
clockwise direction.
The microphone has a protection grid which can also be unscrewed and
removed, great care must be taken to ensure that this is NOT removed.
Underneath the protection grid is the microphone diaphragm which should
never be touched or be subject to dust or dirt. Doing so may damage the
microphone beyond repair or affect its acoustic response.
