The three things you hear

Pitch, loudness, and timbre — every knob on every synth ultimately moves one of these three.

Sound is air vibrating. When anything vibrates fast enough — a string, a speaker cone — your ear picks it up as a tone. Every tone you will ever shape on a synthesizer differs in exactly three ways: how fast it vibrates, how hard it vibrates, and what shape the vibration has.

How fast: frequency is pitch

The speed of vibration is called frequency, measured in Hertz (Hz) — cycles per second. 110 Hz is the low A a bass player tunes to; 440 Hz is the A an orchestra tunes to. Doubling the frequency always raises the pitch by exactly one octave: 110 → 220 → 440 → 880 Hz are all the note A. That doubling rule is why musical pitch feels like a ladder — and why the frequency slider below moves in octaves, not equal steps.

How hard: amplitude is loudness

The size of each vibration is its amplitude — how far the speaker cone travels. Bigger swing, louder sound. Amplitude is the dimension volume knobs, faders, and (later) envelopes operate on. It is completely independent from frequency: a quiet high note and a loud low note are just different corners of the same two-dimensional space.

What shape: waveform is timbre

Two sounds can share the same pitch and loudness and still sound nothing alike — a flute and a violin playing the same note, softly. That difference is timbre, and it lives in the shape of the vibration. The next lesson takes this apart properly; for now, just flip between the four wave shapes below and hear the character change while pitch and loudness stay put.