Brüel & Kjær 3638 Manuel De L'utilisateur page 18

14 Exhaust Noise Inspector Type 3638 – User Manual
Subtraction of Measurement Values Setting
National regulations allow for the subtraction of certain sound level values from measurement
results to compensate for measurement inaccuracies, test site and environmental influences, as
well as vehicle age. To choose the sound level value in decibels (dB), do the following:
1) Press OK to select the parameter.
2) Use to scroll through dB values that can be subtracted.
3) Press OK to confirm your selection and proceed to the next parameter.
Number of Measurements Setting
National regulations may require a certain number of sound level measurements to be per-
formed. To set the required number, do the following:
1) Press OK to select the parameter.
2) Use to scroll through the total number of measurements to perform.
3) Press OK to confirm your selection and proceed to the next parameter.
Result Value Setting
Some regulations require the maximum RMS value to be reported, while others require an
average value from a predefined number of measurements. To choose the criteria to which you
must comply, do the following:
1) Press OK to select the parameter.
2) Use to scroll between the result RMS value options: Maximum or Average.
3) Press OK to confirm your selection and proceed to the next parameter.
Background Noise Measurement at Startup
According to national regulations, measurement of exhaust noise levels may only take place in
an environment where background noise is at least 10 dB below the exhaust noise to be meas-
ured. To ensure compliance of this requirement, you can measure background noise levels every
time you switch on Type 3638 A/B. To allow this automatic measurement, do the following:
1) Press OK to select the parameter.
2) Use to scroll between Yes and No (default). Choose Yes.
3) Press OK to confirm your selection and proceed to the next parameter.