A spectrum’s relative harmonics become real frequencies when scaled by the fundamental

Evidence

The frequency spectrum tells us how much energy the signal has at any particular harmonic. We can convert Figure 1.47 to a real frequency in Hz simply by multiplying each value of relative frequency, F, by the fundamental frequency f0. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2744

Categorization

• DEFINE: Clarifies the relationship between plotted relative frequency and absolute frequency in Hz.