Table 1. Corrections for Computing TWA from L-AVG.
Values in this Table were computed from the formula:
Considerations of Measurement and Accuracy
An integrating meter such as the MICRO-15 Noise Dosimeter integrates all
continuous, intermittent and impulsive sound levels within its range. This avoids
many of the potential errors created by attempting to read and correctly
interpolate the readings of sound level meters in fluctuating sound fields.
However, it is important to use the instrument properly and to understand its
limits in order to achieve the maximum accuracy.
Microphone location generally has the greatest effect on the accuracy of any
noise measuring instrument. The correct placement of the MICRO-15
microphone has been discussed under "Effects of Operator Presence."
Threshold discontinuity can cause notable differences in readings on
various meters if the noise level is near the threshold of the units. Since the
instrument does not measure noise that is even slightly below the threshold, such
noise is not accumulated into the results while a noise level just slightly higher is
accumulated. This is most noticeable in the readings of dose if the threshold is
the same as the criterion level.
Peak noise levels greater than the range of the instrument are "clipped" and
act as if they were at the maximum level of either 146 dB on the 50 dB range or
126 dB on the 40 dB range.
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