The masking from different maskers has to be added to form the final masking threshold. One could argue that either the power or the absolute amplitude of the individual masks should be added. According to , though, addition of two equal masks can give a resulting mask up 12 dB higher than two masks alone. This would mean, that the addition of masks would be defined as follows:
i.e as the addition of square roots of amplitudes. This model does not work for big differences in and , so in the coder the addition was defined as addition of amplitudes:
Using this model for summation, all spectral components of the audio are considered maskers, and their individual masks (calculated in section 3.2.5) are added to form the masking threshold.
An example of the produced masking threshold, including both simultaneous and temporal masking (described in section 3.3), can be seen in figure 5.