Jazz Foundations - Intervals and Chords

Basic building blocks - Intervals

Intervals form the foundation of music. Here, we explore the basic major and minor intervals, with middle C as our reference. Being able to recognize intervals by ear is crucial for understanding chords, melodies, and more.

Triads and 7th chord

Here, we create chords using intervals, focusing on triads and 7th chords, which are formed by stacking thirds.

Triads are three notes built off either major or minor 3rds.

• Major triads: major 3rd + minor 3rd, sounds bright, happy, and majestic. Noted as Cmajor, Cmaj or Ctriad

• Minor triads: minor 3rd + major 3rd, sounds darker, somber. Noted as Cminor, Cmin, Cm, or C-

• Augmented triads: major 3rd+ major 3rd, sounds open, playful or dreamy. Noted as Caug or C+,

• Diminished triads: minor 3rd + minor 3rd, sounds uncertain. Noted as Cdim or C°

If we stack additional 3rds on top of Triads, we can create 7th chords. Same concept can be apply to 9th, 11th or 13th chord.

• Major 7: major triad + major 3rd. Often used as 1st chord in a major key. Noted as Cmaj7, CΔ7, CM7.

• Dominant 7: major triad + minor 3rd. Often used as leading chords to a major/minor 5th below or served as a tonic chord in blues, eg: C7 to Fmaj7. Noted as C7.

  • It is key to blues, blending a major triad with a minor seventh creates a "bluesy" tension—both stable and unresolved, giving blues its distinctive emotional color. It acts as a leading/tonic chord e.g., C7 to Fmaj7. It’s the foundation of 12-bar blues progressions, using three dominant 7th chords, using C blues as example: I (C7), IV (F7), and V (G7). Will dive deep more in a separate article.

• Minor 7: minor triad + minor 3rd. Often used as 2 in the 2-5-1 chord progression. It can also be used as the tonic of a minor key but less common.

We covered some basic building blocks and chord harmony concepts in the above two section. List some other basic key elements below, and will dive into them in a separate article. Examples: Chord progressions, Groovy and rythm, Forms (12 bar blues is one example form), Scales and Ear training etc.