Larson Davis SoundAdvisor 831C Reference Manual page 51

Module 5 Calibrating Your SoundAdvisor 831C
In this module:
5.1 Understanding the Calibration Process .............................................................................5-1
5.1.1 Determining Microphone Sensitivity ...................................................................5-1
5.1.2 Determining Noise Floor, Overload, and Under Range Levels ........................... 5-1
5.1.3 Understanding Calibration Stability .................................................................... 5-2
5.2 Choosing a Calibrator .........................................................................................................5-2
5.3 Reviewing the Calibration Settings .................................................................................... 5-3
5.4 Calibrating Your SoundAdvisor 831C ................................................................................. 5-5
5.4.1 Calibrating While Using Meter Security (Lock Mode) ..........................................5-6
5.1 Understanding the Calibration Process
5.1.1 Determining Microphone Sensitivity
5.1.2 Determining Noise Floor, Overload, and Under Range Levels
SoundAdvisor Model 831C
In this section:
• 5.1.1 Determining Microphone Sensitivity
5.1.2 Determining Noise Floor, Overload, and Under Range Levels
•
The primary role of sound level meter calibration is to establish a numerical
relationship between the sound level at the diaphragm of the microphone
and the voltage measured by the meter so that the sound pressure level can
be read directly from the display of the meter in dB. The result of a calibration
is the determination of the sensitivity of the meter, including microphone and
preamplifier, typically in dB re 1V/Pa or mV/Pa.
A secondary role of calibration is to determine the sound level which would
overload the instrument (Input Overload level) and the minimum sound level
(Under Range level) that can be accurately measured without being
influenced by the operational noise from the meter (Noise Floor).
Noise Floor Level
The noise floor is calculated as the energy sum of the noise generated by the
microphone, preamplifier, and instrument circuitry. The appropriate noise
floor, and nominal sensitivity compute automatically in the 831C with the
following preamplifiers and their commonly paired microphones:
• PRM831
• PRM2103
• ICP with ADP074
Understanding the Calibration Process 5-1