9
Chapter 3
Measuring Sound
Always calibrate your dBAir sound level meter prior to and after taking measurements
using a known sound source, such as the Castle GA607 Sound Level Calibrator.
Your dBAir can be set for calibration immediately after the unit has been turned on, see
Startup Options
for further details.
Incidence Angle
It is essential that you hold your dBAir sound level meter at the correct angle to the
noise source depending on the microphone type supplied with your meter.
The type of microphone supplied with your instrument will either be
Free Field
or
Pressure Field
, see below for details of the measuring incidence angle for each
microphone type: -
Pressure Field - (meeting ANSI Standards)
Pressure Field microphones required incidence angle of 90°, therefore whilst
measuring ensure your dBAir sound level meter is at 90° relative to the noise source
being measured.
Free Field - (meeting IEC Standards)
Free Field microphones require an incidence angle of 0°, therefore whilst measuring
always point your dBAir sound level meter directly towards the noise source being
measured.
To comply with legislation all dBAir sound level meters outside of the US are
supplied with a
Free Field
measurement microphone, and a
Pressure Field
measurement microphone within the US
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