Pitch cannot be measured absolutely, only relative to another tone

Evidence

However, the early observations did not allow the measurement of pitch for two reasons. First, as with loudness, we cannot measure the pitch of a pure tone — we can only measure the pitch of that tone relative to another tone. Second, in order to measure the relationship between the pitch of one tone and that of another tone, we need a reference stimulus and a measurement scale. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1237

Categorization

• XREF: Parallels the loudness measurement problem described earlier in the book — same why-relative measurement logic applies across auditory qualities.