Pitch strength rises only modestly with level while loudness explodes.

Evidence

With increasing sound pressure level the pitch strength of pure tones increases. Data displayed in Fig. 5.27 suggest an increase in relative pitch strength by about 10% for each increase in level by 10 dB. Within a level range of 20 to 80 dB pitch strength increases by a factor of about 2.5, whereas the loudness increases by about a factor of 100. Therefore, despite the effect that loudness decreases with tone duration, the decrease in relative pitch strength shown in Fig. 5.26 cannot be explained on the basis of the reduced loudness alone. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 805