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C H A P T E R
5 :
W I D E
B A N D
A U D I O
Q U A L I T Y
T E S T I N G
Figure 5.15: Excitation result styles
Figure 5.16: The Excitations diagram
NMR
The measurement scheme NMR (Noise-to-Mask Ratio) [BRAN87] evaluates the
level-difference between the masked threshold (the maximum level of a not
audible error) and the actual noise (error) signal. NMR is defined as the ratio
between the error signal to the masked threshold. The masked threshold is
estimated for each band of the Bark scale.
Negative values of the NMR provide an estimation of the existing safety margin.
Positive values signify an estimation of the audible noise energy. Figure 5.17
shows the select signal window for the NMR diagram type. The resulting
diagram is shown in Figure 5.18.
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