## What makes an octave?

An octave occurs when one note's frequency is exactly double another's. Your brain perceives these two pitches as fundamentally "the same note" — just higher or lower. It's a harmonic coincidence that really resonates with people.

— Hz

Hertz so good when you hear it.

## Press and play

Tap any key below. Notice how both A notes (highlighted) sound like the same pitch at different heights? Don't worry — we won't string you along.

## The perfect 2:1

A4, the tuning standard, vibrates at 440 times per second. A5 vibrates exactly 880 times. Twice the frequency, same musical identity. It's note complicated.

1 cycle
→
2 cycles

When you play them together, they're pitch perfect partners.

## Explore the spectrum

Pick any base frequency. Its octave is always double. The math scales beautifully — no sharp edges here.

Base frequency 220 Hz

Go ahead, slide around. We're on the same wavelength.

## Why does this matter?

The 2:1 ratio is nature's favorite interval. It's why we name notes in repeating cycles (A, B, C... then A again). Every musical scale, from ancient modes to modern pop, rests on this foundation.

When waves align in simple ratios, they sound consonant. The octave is the simplest ratio of all — and that's something we can all tune into.

It's sound science, really. We're not just making this up flat.