Click any note to hear it · Explore harmonic relationships · Visualize chord progressions
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Circle of Fifths
Chord Progression
Click notes to build a progression…
Click a note on the circle to see its harmonic information
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Coltrane Matrix
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Live Analyzer
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Listening to microphone…
SPECTRUM
WAVEFORM
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— Hz
♭In Tune♯
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AI Audio Analysis
Upload a snippet · Detect chords, key & tempo · Visualize on the Circle of Fifths
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Drop audio here
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Analysis Results
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Upload an audio file and click Analyze Audio to get started
✦ AI Harmonic Insight
Synthesizer Keyboard
Play notes · Build chords · Explore scales in real time
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Piano Keyboard
Keys: A W S E D F T G Y H U J
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Chord Builder
C Major
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Scale Explorer
Music Theory Reference
Deep dives into the harmonic concepts powering this app
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Circle of Fifths
The Circle organizes 12 pitch classes by ascending perfect fifths. Each clockwise step adds one sharp; counter-clockwise adds one flat. Adjacent keys share the most notes and are closely related harmonically — the foundation of tonal music theory.
Adjacent keys share 6 of 7 scale tones
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Coltrane Matrix
John Coltrane's 1959 "Giant Steps" divided the octave into three equal major thirds (B→G→E♭), creating a symmetrical harmonic cycle. Coltrane navigated these distant key centers at breakneck speed — known as "Coltrane changes" — revolutionizing jazz harmony.
3 tonal centers · major thirds apart · 120° symmetry
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Frequency & Spectrum
Each musical note corresponds to a precise frequency in Hz. A4 = 440 Hz by modern standard. Every octave doubles the frequency. The audible spectrum spans 20 Hz to 20,000 Hz, divided into regions: sub bass, bass, low mid, mid, high mid, and high.
A4 = 440 Hz · Each octave = ×2 frequency
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Waveform Types
Sine waves produce pure tones with no harmonics — smooth and clean. Triangle waves add soft odd harmonics. Sawtooth waves contain all harmonics (bright/buzzy). Square waves contain odd harmonics only (hollow/reedy). Real instruments combine thousands of partials giving them unique timbre.
Timbre = the shape of the waveform over time
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Chord Theory
Chords are built by stacking thirds. Major triads use root + major third (4 semitones) + minor third (3 semitones). Seventh chords add a fourth tone. The specific intervals between notes define emotional character — major sounds bright, minor dark, diminished tense.
Triads → 7ths → 9ths → 11ths → 13ths
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Modal Scales
Seven modes derive from the major scale starting on different degrees. Ionian (major) = happy; Dorian = jazzy-minor; Phrygian = Spanish/dark; Lydian = ethereal; Mixolydian = bluesy; Aeolian (natural minor) = melancholy; Locrian = dissonant/unstable.