Recognise Any Chord by Ear

What chord recognition actually trains

Recognising a chord by ear is not one skill but two stacked on top of each other. First you hear that several notes are ringing together and not just one, then you hear the specific relationship between those notes that makes it major rather than minor, or diminished rather than augmented. The second part is where most players stall, because the difference between a minor and a diminished triad is a single note moved by one semitone.

Chord quality: major, minor, diminished, augmented

These four triads are the alphabet everything else builds on. Major sounds resolved and bright. Minor sounds resolved but darker. Diminished sounds unstable, pulling to resolve somewhere. Augmented sounds unresolved in a different way, stretched rather than pulled. Learn to place any triad into one of these four buckets first, before worrying about anything more specific, and the rest of chord recognition gets much easier to build on top.

Hearing extensions and colour notes

Once triads are solid, the next layer is what sits on top of them. Adding the 7th is the single biggest colour change in harmony: a plain C major turns moody as Cmaj7 or bluesy as C7 without moving the triad underneath it at all. Beyond the 7th, 9ths add a bright, open colour that shows up constantly in jazz and neo-soul. Train these in the order you meet them in real music: triad quality first, then 7ths, then 9ths, each one a small addition to a shape your ear already knows.

See roughly what the browser hears

Pick a chord below and watch the 12 bars. Each bar is one pitch class (C through B), and its height is how much of that pitch is present in the sound right now, a simplified live version of the same idea the microphone engine uses to identify a chord from audio:

How the microphone chord detection works

Chroma analysis in your browser

The game's microphone engine does not try to identify individual notes the way a tuner does. Instead it runs the incoming audio through an FFT, sorts the energy at every frequency into one of 12 pitch-class buckets (C, C#, D, and so on, ignoring which octave), and ends up with a 12-number fingerprint of what is currently sounding. A C major chord lights up the C, E and G buckets; a C minor chord lights up C, Eb and G instead. That fingerprint gets compared against templates for every chord quality the engine knows, and the closest match, above a confidence threshold, wins.

To avoid one noisy instant flipping the answer, the engine also requires that fingerprint to stay stable and confident across several analysis passes in a row, taken every few dozen milliseconds, before it commits to a chord. That is the main practical difference from MIDI: a MIDI keyboard reports exact notes the instant you press them, while microphone detection waits for the sound to settle into something it is confident about.

Works with piano, guitar and more

Because the analysis works on the sound itself rather than on a signal from specific hardware, it does not care whether the chord came from an acoustic piano, a guitar, or anything else that can ring out a clean chord. What it does care about is a together strike in a reasonably quiet room: a strum rolled out note by note, or a chord buried under background noise, reads as a smear across several pitch classes rather than a clean fingerprint, and takes longer to confirm or gets missed.

Practice modes that keep you coming back

Chord recognition is not walled off in its own quiz screen, it is the microphone path built into every chord mode in the game. Play Chord Training's Standard Levels, Custom mode, or Survival with a mic instead of a MIDI keyboard, and the same chroma engine listens for whatever chord the level asks for next. Each mode's built-in variety, rising speed, custom chord pools, survival pressure, does the job of keeping practice from going stale, while the recognition itself works the same way underneath every one of them.

Practice this in the game

Start in Custom mode with a small pool: C major, C minor, and one you regularly confuse them with, and play into your microphone instead of a keyboard. Strike each chord cleanly and let it ring for a moment rather than rolling it, since a rolled chord is exactly the kind of smear the detection struggles with. Once major and minor triads confirm instantly and reliably, widen the pool to 7ths, then 9ths, following the same layered order the theory works in.

Common questions

Does chord recognition need a MIDI keyboard?

No, that is the point of it. Chord recognition is the microphone path: your acoustic piano, guitar, or any instrument gets picked up by the mic, analysed in the browser, and matched against a chord, with no MIDI hardware involved.

What chord qualities can the microphone recognise?

Major, minor, augmented, diminished and half-diminished triads and near-triads, suspended 2nd and 4th chords, the four common seventh types (maj7, min7, dom7), and three ninth chords (maj9, min9, dom9). Wider extensions like 11ths and 13ths are MIDI-only for now, since they need cleaner note-level detail than audio analysis reliably gives.

Does it work with guitar, or only piano?

Any instrument that can sound a chord clearly works, piano and guitar both included, because the analysis listens to the sound itself rather than to a specific instrument's signal. A clean, in-tune, together strike is what it needs, not a particular brand of gear.

How accurate is microphone chord detection compared to MIDI?

MIDI is exact: it reads the notes you pressed directly, no guessing involved. Microphone detection is an estimate from sound, so it only confirms a chord once it has stayed stable and confident across several analysis frames in a row. That makes it a little slower to commit than MIDI, and pickier about clean, together strikes, but reliable once you strike cleanly. Pair it with ear training to build the listening half of the same skill.