Microphone And Pre-Amplifier; Microphone Types - Castle group dBAir Operating Manual

Microphone and Pre-Amplifier

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.

Microphone Types

Three different types of microphone are manufactured, and each is 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 dBAir sound level meter 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 Field
Sound Incidence Angle = 90°
Point the sound meter at 90° to the noise source
Random Incidence Field
Point the sound meter at approximately 70° to the noise source
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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