What's Inside This Sound?
Any sound is just a pile of sine waves stacked up. An analyser can find the loudest frequencies, and you can toggle each one on and off to hear what it contributes.
The Fourier Idea
Pick a sound and press Play. You'll hear it looping. It might be a piano, a clarinet, a bright sawtooth, or a warm pad. They all sound different, but under the hood they're all made of the same ingredient: sine waves at different frequencies and amplitudes.
Now press Capture. The analyser finds the 16 loudest frequencies in the sound and creates a sine wave for each one.
Toggle the individual sines on and off. Each one contributes something to the overall sound. The lowest one is usually the fundamental pitch. The higher ones add brightness and character.
Switch between Original and Reconstruct to hear how close the 16-sine version gets. It won't be perfect, but you can hear the family resemblance.
Try it - pick a sound source, press Play, then Capture to see and hear its sine wave components.
What You're Hearing
When you capture a piano sound, you'll see a strong fundamental around 262 Hz (C4) and a series of harmonics at integer multiples: 524, 786, 1048 Hz and so on. Each harmonic is quieter than the last, and the higher ones decay faster. That's what gives a piano its characteristic brightness on the attack that mellows out over time.
The clarinet is different. It has mostly odd-numbered harmonics: the 1st, 3rd, 5th, 7th. The even harmonics are nearly absent. That's why a clarinet sounds hollow compared to a violin playing the same note.
A sawtooth wave has every harmonic, evenly spaced, each one weaker than the last. That's why it sounds bright and buzzy. And the soft pad has just a few slightly detuned sines, giving it warmth without edge.
Why 16 Sines?
Sixteen is a practical compromise. Real sounds contain hundreds or thousands of frequency components. But the loudest 16 capture most of the recognizable character. You can hear the difference between 4 and 16 sines clearly. Going from 16 to 64 matters less. The first few partials carry the identity of the sound; the rest fill in texture and nuance.
This is the foundation of additive synthesis: if you know which sine waves make up a sound, you can reconstruct it. Vocoders, spectral processors, and resynthesizers all start with this same idea.