What Is an Interval — Eight Distances, Once

An interval is a distance, not a height — that is how it gets heard

Click the buttons below. First play C4 alone, then E4 alone, then play them together.

This page builds exactly one idea: an interval is a distance, not a height.

Why "distance" matters more than "height"

If an interval were only "higher or lower", it would be the same thing as pitch — not a separate idea.

But treat it as a distance and three common facts explain themselves at once:

• Why two notes together "blend" — close intervals overlap heavily and are heard as one body;
• Why major and minor thirds are both consonant — both sit close enough not to fight;
• Why intervals beyond an octave must be heard as "two things" — too wide to register as one note.

The groups below are the ruler of this distance. Each is a minor second — the smallest step.

The eight basic intervals

Stacked from one note upward:

• Perfect unison (0 semitones) — the two notes are identical
• Minor second (1) — the nearest distance, but it "clashes"
• Major second (2) — one step
• Minor third (3)
• Major third (4)
• Perfect fourth (5) — sounds "open"; common in folk
• Perfect fifth (7) — the most consonant; skipping to it barely registers as a leap
• Minor sixth (8)
• Major sixth (9)
• Perfect octave (12) — same name, one octave higher

Start with only three groups — feel the idea of "distance", don't memorise names.

An observation you can check yourself

Below is a perfect octave — C4 and C5. Same name, an octave apart.

If an interval were only "distance", a perfect octave should sound like "the same note, very far away". And it does — many people cannot tell an octave from a unison at all.

Next try a perfect fifth (C4 and G4). It spans *less* than the octave, yet the sense of openness is stronger.

That is the difference between consonant and open: the octave is a unison relation, the fifth is an open one. Distance and consonance are not the same thing.

Listen to three first

One: perfect unison (C4 and C4) — the two notes are identical; you hear one sound.

Two: minor second (C4 and D♭4) — the nearest distance, but it clashes.

Three: perfect fourth (C4 and F4) — a middle distance that sounds open.

How to practise

1. Use only the "together" button at first, ignoring names; 2. Then try the other order (second note first) — a different order feels different; 3. Only look at the note names after five or more attempts.

"Hear it first, name it second" is the core of this site's ear-training page; this tool uses the same method.

Next

• Practising "hearing it": interval identification drill
• The two that differ by half a semitone: major and minor thirds
• The big leaps above the octave: compound intervals
• Definitions and terminology: the music glossary.

Sources

• 本页为音程听辨工具的说明与练习，音名与度数依据通用乐理记法
• 实例均标注来源与许可档位，可在线试听；练习用的合成音由浏览器实时生成，非录音

Used for fact-checking only; all prose is original.