Music Theory: Intervals

Master the fundamental building blocks of melody, harmony, and musical expression

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Understanding Musical Intervals

Intervals are the distances between notes and the foundation of all music theory. They determine the character of melodies, the quality of chords, and the emotional impact of harmonic progressions. Master intervals to unlock the secrets of musical expression.

What Are Musical Intervals?

A musical interval is the difference in pitch between two notes. Intervals can be measured in semitones (half-steps) and are classified by their size and quality. Understanding intervals is essential because they determine:

Harmonic Function

  • Chord quality (major, minor, diminished, augmented)
  • Harmonic tension and resolution
  • Voice leading in progressions
  • Harmonic extensions and alterations

Melodic Character

  • Melodic contour and shape
  • Emotional expression and mood
  • Phrase structure and direction
  • Musical style and genre characteristics

Interval Categories

Perfect Intervals

Stable, consonant intervals that sound complete and resolved.

Unison
Perfect 4th
Perfect 5th
Octave

Major Intervals

Bright, happy intervals that create major chord qualities.

Major 2nd
Major 3rd
Major 6th
Major 7th

Minor Intervals

Darker, more emotional intervals that create minor chord qualities.

Minor 2nd
Minor 3rd
Minor 6th
Minor 7th

Augmented/Diminished

Altered intervals that create tension and need resolution.

Tritone

Interval Theory Fundamentals

Measuring Intervals

Semitones (Half-Steps)

The smallest interval in Western music. 12 semitones = 1 octave.

Letter Name Distance

Count the letter names: C to E = 3rd, C to G = 5th.

Quality Classification

Perfect, Major, Minor, Augmented, Diminished.

Consonance & Dissonance

Perfect Consonance

Unison, Perfect 4th, Perfect 5th, Octave - Completely stable

Imperfect Consonance

Major/Minor 3rds and 6ths - Pleasant but not completely stable

Dissonance

2nds, 7ths, Tritone - Create tension, need resolution

Complete Interval Reference

Musical Applications

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Melody Construction

Intervals create the shape and character of melodies

  • Stepwise motion uses 2nds
  • Leaps use larger intervals
  • Octave jumps for dramatic effect
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Harmony Building

Chords are built by stacking specific intervals

  • Major chords: Root + Major 3rd + Perfect 5th
  • Minor chords: Root + Minor 3rd + Perfect 5th
  • Dominant 7ths add Minor 7th

Tension & Resolution

Dissonant intervals create tension that resolves to consonance

  • Minor 2nd resolves down
  • Major 7th resolves up
  • Tritone resolves outward
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Emotional Expression

Different intervals evoke specific emotional responses

  • Minor 3rds sound sad
  • Major 3rds sound happy
  • Perfect 5ths sound powerful

Interval Practice Exercises

👂 Ear Training

  • Practice interval recognition by ear
  • Start with perfect intervals
  • Use interval training apps
  • Sing intervals with solfege
  • Identify intervals in songs

🎸 Fretboard Practice

  • Find intervals on single strings
  • Practice cross-string intervals
  • Use different fingering patterns
  • Map intervals across positions
  • Practice interval sequences

📝 Theory Application

  • Analyze chord structures
  • Study interval progressions
  • Compose with specific intervals
  • Transcribe melodic intervals
  • Practice interval math

Intervals in Common Progressions

Chord Construction

Major Triad

Root + Major 3rd + Perfect 5th

Example: C - E - G (0-4-7 semitones)

Minor Triad

Root + Minor 3rd + Perfect 5th

Example: C - Eb - G (0-3-7 semitones)

Dominant 7th

Root + Major 3rd + Perfect 5th + Minor 7th

Example: C - E - G - Bb (0-4-7-10 semitones)

Melodic Movement

Stepwise Motion

Movement by 2nds (Major and Minor)

Smooth, flowing melodic lines

Leaps

Movement by 3rds, 4ths, 5ths

More dramatic melodic contours

Large Intervals

6ths, 7ths, Octaves and beyond

Bold, expressive melodic statements