Pitch strength grows linearly with log duration up to 300 ms.

Evidence

With increasing duration the pitch strength of pure tones increases. Results displayed in Fig. 5.26 suggest an almost linear increase of pitch strength with the logarithm of the test-tone duration up to a duration of about 300 ms. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 804