Masking reduces to a comparison of excitation-level patterns over frequency and time

Evidence

The basis of masking is always the same: the ratio (spectrally and temporally) between the excitation level versus critical-band rate versus time patterns produced by the masker, and that produced by the test sound is ultimately responsible for whether the test sound is heard or not. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 613