Pure-tone versus noise masking differences depend on masker frequency

Evidence

The results displayed in Fig. 4.38 indicate that lower slopes of pulsation patterns for pure tones, compared with critical-band wide noise, differ for maskers at 2 kHz and to a lesser degree for maskers at 4 kHz. At 0.4 and 1 kHz, the pulsation patterns of critical-band wide “masker” and pure tone “masker” yield similar patterns. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 607