Level Calibration
This paragraph describes level calibration using a pistonphone. This is the kind of calibration you
would most often perform prior to measuring. How to perform a frequency calibration is described
on page 16.
Do not attempt to remove the microphone from the RA0045. You will be calibrating the RA0045
as a whole with a Pistonphone fitted with a ½” coupler. This, in effect, increases the coupler
volume such that the signal from the Pistonphone will be reduced by 1.03 dB
.
1) Snap the spring-loaded clamp (see Fig. 1) to its upright position, or remove it.
2) Unscrew the collar of the Pistonphone and remove the O-ring (see Fig. 11).
Entrance to
Pistonphone coupler
O-ring
Collar
RA0045
Ear Simulator
Fig. 11.
Calibration using the Pistonphone
a) Unscrew Pistonphone collar and remove O-ring.
b) Place coupler over RA0045, push gently down to the stop
c) Switch on
3) Place the coupler of the Pistonphone over the RA0045, push it gently down to the stop and
switch on.
4) Set the analyser to either wide band or to the
⅓
octave band whose centre frequency is
250 Hz.
5) When conditions are stable, adjust the analyser so that it correctly gauges the Pistonphone
signal (nominally 114 - 1.03 = 112.97 dB). See Pistonphone manual for making barometric
corrections.
6) Switch the Pistonphone off and remove it from the RA0045.
7) Re-assemble the pistonphone.
15
LI0070 – 28 June 2017
