# Inside a note

Take a sound apart. Shape its harmonics, see the waveform, and listen to the same pitch change character.

Eight sine waves at integer multiples of a fundamental add to a periodic sound. Change their amplitudes to explore the spectrum. A pitch can remain perceptible without the fundamental component. This is a simplified synthesis demonstration, not a hearing test. Real instrument timbre also depends on envelope, noise and other factors.

y(t) = Σ aₙ sin(2πnft), n = 1…8.

Pure: only a₁=1. Round: 1/n². Hollow: odd harmonics 1/n. Bright: 1/n. Common gain: 1/max(1,Σ|aₙ|). Zero initial relative phases. Audio output additionally scaled to 0.14. Loudness is not equalized. The drawing shows two periods and optional slowed motion.

## Sources
- [UNSW: Spectrum, harmonics and timbre](https://www.animations.physics.unsw.edu.au/jw/timbre-spectrum.htm)
- [UNSW: Voice acoustics](https://www.phys.unsw.edu.au/jw/voice.html)