06
F0: The First Line on the Spectrum
F0 (fundamental) = pitch. On the spectrum it is the leftmost, usually tallest line.
Remember? Harmonics are integer multiples of F0: H1 = 1×F0, H2 = 2×F0, H3 = 3×F0… So when F0 changes, all the spectral lines shift together (like an accordion). The app uses the YIN algorithm to find this "most basic vibration period" in the waveform — in other words, it finds F0.
Experiment 6 · Drag F0, the Whole Spectrum Shifts
Drag the F0 slider (the red highlighted line marks where F0 is). Watch all spectral lines move together like an accordion while the pitch changes. This is what "changing a note" looks like on the spectrum.
📌 Remember this
F0 = the leftmost line on the spectrum = your pitch. The app's "pitch" chart and register detection both start from F0.