Tonal harmony is the foundation of most Western music, from Bach to jazz standards. At its core, it is a contract between composer and listener: if you follow its rules, the listener will always feel a sense of home—a tonal center called the tonic.

This sense of direction comes from how chords function and move within three main regions of tonality:

The Three Regions of Tonality

Every chord in tonal harmony has a function—a role it plays in the story of tension and release. These functions are grouped into three regions:

1. Tonic (Home Base)
   • The point of rest, least tension.
   • Where the music feels settled.
   • Example: C major in the key of C.
2. Subdominant (The Journey)
   • Transitional, moderate tension.
   • Feels like moving “away from home.”
   • Often described as “the mountain” in hymns, descending back to tonic.
3. Dominant (The Tension)
   • The highest level of tension.
   • Creates expectation to return to tonic.
   • Think of it as “the storm at sea” before returning to safe harbor.

The Circle of Fifths & The Harmony Map

The circle of fifths organizes all 12 tones and shows how chords relate to each other. By building triads on each scale degree in C major and C minor, we can classify every chord into one of the three regions.

• The V7 chord (G7 in C) always sits at “1 o’clock” on the map.
• The IV chord (F in C) is always at “11 o’clock.”
• The I chord (C) is always at “12 o’clock.”

This fixed placement means that no matter what key you’re in, functions always live in the same place.

Harmonic Progressions & Cadences

Music is a journey through this map. Each path between regions creates a recognizable cadence:

• V7 → I = Perfect Authentic Cadence (dominant to tonic).
• IV → I = Plagal Cadence (subdominant to tonic, “Amen” ending).
• ii → V7 = Subdominant to Dominant motion (the backbone of jazz progressions).

These are the main roads of tonal harmony. Exploring alternative “roads” is what reharmonization is all about.

A Real Example: “Sweet Home Alabama”

At first glance, the famous progression in Sweet Home Alabama seems to move from dominant → subdominant, which doesn’t establish the key strongly. This illustrates how important functional paths are in determining the real tonal center of a piece.

Key Takeaways

• Tonal harmony organizes chords into three regions: tonic, subdominant, dominant.
• Each chord function has a fixed place on the circle of fifths map.
• Cadences are the most effective paths, guiding the listener’s sense of key.
• Understanding these paths is the first step toward reharmonization.

Practice It Yourself

Try mapping out all diatonic functions in every key. Start with C major and C minor, then expand. Use worksheets like the one in The Art of Reharmonization or explore interactively in Mapping Tonal Harmony Pro.

Want to dive deeper? Check out the full Art of Reharmonization book or explore tonal harmony interactively with Mapping Tonal Harmony Pro.