Large primary frequency separations yield multiple cancellation-level notches

Evidence

These tendencies become striking for 11f = 1000 Hz. Cancellation level as a function of L1 shows not just one notch but two or perhaps three notches; the phase decreases in a step-like manner at almost exactly those values of L1 at which the cancellation level shows a minimum. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1583