The gap width producing a Zwicker tone depends on line spacing

Evidence

These equations can be interpreted as follows: the minimum spectral gap necessary to produce a Zwicker tone, when expressed in critical bands, corresponds to the ratio of a constant number and the critical-band rate of the spectral gap’s centre. The magnitude of the constant number depends on the line spacing. Starting from a line spacing of 1 Hz, the width of the spectral gap expressed in critical bands increases by a factor of 1.5 for 20-Hz line spacing and by a factor of 3 for 200-Hz line spacing, in order to delimit the existence region of the Zwicker tone for narrow spectral gaps. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 765