Complex Waves: Why the Human Voice Is Not a Single String
Real sound = fundamental + a stack of integer-multiple overtones. How strong each overtone is decides the timbre.
If sound were a single sine wave, every instrument and every voice would sound identical — a monotonous "beep". Real sound is many frequencies vibrating at once: besides the fundamental F0 there are its integer multiples 2×F0, 3×F0… which we call harmonics H1 (=F0), H2 (=2×F0), H3 (=3×F0). How strong each harmonic is decides the timbre.
Experiment 4 · Take Sound Apart and Stack It Back
Drag the 8 sliders below to adjust how strong each harmonic is. Each row above is one harmonic's waveform; the bottom row is the real sound waveform after they are summed. Try "turning everything off except H1" (it becomes a pure tone), then gradually add H2, H3 back — the "timbre" you hear changes.
Harmonics are "integer-multiple friends of the same fundamental". They decide whether a voice sounds thick, bright, or dark. In the next chapter you will see: a spectrum chart is simply these "friends" lined up by frequency.