Strutt|Criteria|Curves|Noy inserts the equal-noisiness (Noy) curves from ISO 3891 into the current row of the worksheet. The user can adjust which noy value is displayed by changing the value in Column D.
The equal-noisiness curves were developed to quantify impacts from aircraft noise and are used as part of the Perceived Noise Level rating.
The user has the option of inserting Noy curves based on the values in Table 13 of the standard or based on the formula in the standard (combined with the constants in Table 14). In theory, Noy curves based on Table 13 should have the same spectral values as Noy curves based on the formula; but slight discrepencies between the two have been found in some instances.
Reference: ISO 3891 (1978) Acoustics - Procedure for Describing Aircraft Noise Heard on the Ground