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Chapter 2
Microphone
Measurement microphones by the very nature of their manufacture are
precision components that are easily damaged through incorrect use. Great
care must be taken when using the instrument to ensure the longevity of the
microphone.
Please note that depending on your instrument model, it may be supplied
with a protective white plastic cap covering the end of the microphone. If
supplied this cap must be removed prior to using the instrument.
Microphone Types
Three different types of microphone are manufactured, each designed for
measuring noise in different applications which is out of the scope of this
manual. Each one however has a different sound incidence angle. The sound
incidence angle determines the angle the instrument is held relative to the
actual noise source being measured.
Free Field
Sound Incidence Angle = 0°
Point the sound meter directly towards the noise source
Pressure
Sound Incidence Angle = 90°
Point the sound meter at 90° to the noise source
Random Incidence
Point the sound meter at approximately 70° to the noise source
All Sonus meters are supplied with
Free Field
measurement microphones.
Microphone Polarisation
Microphones require a polarisation voltage to operate and are manufactured in
two ways. All microphones supplied with Sonus meters are
Pre-Polarised
.
Externally Polarised
These microphones require an external charge for the microphone to operate
which is generally 200V and supplied by the sound level meter.
Pre-Polarised
These microphones generate the polarisation voltage internally and do not
require the externally generated 200V polarisation charge.
