Two-tone suppression makes simultaneous masking appear broader than forward masking

Evidence

Because the masker suppresses the signal, the level of the masker that is needed to mask the signal will be lower than if the signal were not suppressed. As a result, the masker level at threshold is lower in the simultaneous condition than the same masker in the forward-masked condition, where suppression is not active. If we apply this principle to the simultaneously masked PTC, the masker components that fall within the suppressive region around the signal require lower masker levels to mask the signal, causing tuning to appear to be broader than when measured under forward-masking conditions. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 535

Categorization

• XREF: Explains why simultaneous and forward-masked tuning curves disagree — relevant to modeling hearing-impaired vs. normal frequency selectivity.