For broadband noise, AM detection extends up to 500 Hz without sideband interference

Evidence

For low modulation frequencies, the broken curve in Fig. 7.2, which represents the data for white noise, runs parallel to that for tones, but the increment corresponding to the square root of the modulation frequency continues towards higher modulation frequencies up to 500 Hz. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1022