Broad-band noise masking erases individual differences in quiet threshold

Evidence

It is interesting to note that the strong individual differences in the dependence of threshold in quiet on frequency almost completely disappear when thresholds masked by broad-band noises are measured - an effect that is based on the ear’s frequency selectivity representing masker and test tone within the same band. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 407

Categorization

• QUESTION: Why exactly does noise masking suppress inter-individual variability? The cited mechanism (frequency selectivity unifying masker and tone in one band) could be worth unpacking further.
• corroborated: 2 independent passages support this claim — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 407