Virtual pitch arises only for certain fundamental-to-lowest-component combinations

Evidence

Not all complex tones from which the lower harmonics have been removed elicit a virtual pitch. Rather, specific combinations of fundamental frequency and of the frequency of the lowest component must occur in order to produce a virtual pitch. An existence region of virtual pitch, as displayed in Fig. 5.10, can be defined. It shows the fundamental frequency of a complex tone as a function of the lowest component, below which all spectral components were removed. In order to produce a virtual pitch, spectral components within the shaded area of Fig. 5.10 have to be presented. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 709

Categorization

• QUESTION: Fig 5.10’s shaded existence region — what exactly bounds it physically? Worth chasing what spectral-spacing constraint defines the border.