Understanding Intervals

In music, intervals are the foundation of melody and harmony, defining the distance between two notes in terms of pitch and frequency. Whether you’re a musician or someone interested in music theory, understanding intervals is essential for composing, improvising, and interpreting music. In this article, we will explore the different types of intervals, starting with the smallest and working up to the largest.

What Is an Interval?

A musical interval refers to the distance between two notes. This distance can be measured in terms of the number of steps between the notes in a scale or their frequency ratio. Understanding intervals helps musicians create harmony, build chords, and structure melodies.

Types of Intervals (Smallest to Largest)

1. Perfect Unison (P1)

• Distance: 0 half steps
• Description: The smallest interval possible, where both notes are the same. It’s used to emphasize a single pitch in music.

2. Minor Second (m2)

• Distance: 1 half step
• Description: This interval represents the smallest distance between two different notes, creating a very dissonant, tense sound. A common example is from C to C# (or Db).

3. Major Second (M2)

• Distance: 2 half steps
• Description: A whole step between two notes. This interval has a brighter and less tense sound than the minor second. An example is from C to D.

4. Minor Third (m3)

• Distance: 3 half steps
• Description: A melancholic interval often found in minor chords. This interval spans three half steps, such as from C to Eb.

5. Major Third (M3)

• Distance: 4 half steps
• Description: The major third gives a bright, uplifting sound, and it is a key component of major chords. It is the distance between C and E. Check out the exercises I wrote to practice thirds on piano and guitar.

6. Perfect Fourth (P4)

• Distance: 5 half steps
• Description: A consonant and stable interval, the perfect fourth is frequently used in harmonies. A common example is from C to F. Check out the exercise I wrote to practice fourths on piano and guitar.

7. Augmented Fourth (A4) / Diminished Fifth (d5)

• Distance: 6 half steps
• Description: Also known as a tritone, this interval splits the octave in half and has a very dissonant, unresolved sound. It can be spelled as an augmented fourth (e.g., C to F#) or diminished fifth (e.g., C to Gb).

8. Perfect Fifth (P5)

• Distance: 7 half steps
• Description: One of the most consonant intervals, the perfect fifth forms the backbone of many harmonies and is a key part of power chords. The interval between C and G is a perfect fifth. Check out the exercises I wrote to practice fifths on piano and guitar.

9. Minor Sixth (m6)

• Distance: 8 half steps
• Description: This interval spans eight half steps and has a somewhat dissonant sound compared to the major sixth. An example is from C to Ab.

10. Major Sixth (M6)

• Distance: 9 half steps
• Description: The major sixth has a consonant, sweet sound and is often heard in music with a romantic or lyrical quality. The distance between C and A is a major sixth. Check out the exercises I wrote to practice thirds on piano and guitar.

11. Minor Seventh (m7)

• Distance: 10 half steps
• Description: This interval has a jazzy, unresolved sound and is found in dominant seventh chords. It spans from C to Bb.

12. Major Seventh (M7)

• Distance: 11 half steps
• Description: The major seventh is a dissonant interval, just one half step below the octave. It creates a strong sense of tension and resolution, such as from C to B. Check out the exercises I wrote to practice thirds on piano and guitar.

13. Perfect Octave (P8)

• Distance: 12 half steps
• Description: The octave represents the completion of the musical cycle, where one note doubles its frequency from the other. It’s the interval between C and the next C. Check out the exercises I wrote to practice thirds on piano and guitar.

Interval Qualities

Augmented and Diminished Intervals

Augmented and diminished intervals are formed by altering perfect or major/minor intervals by one semitone.

• Augmented Intervals: When a perfect or major interval is increased by one semitone, it becomes augmented (e.g., an augmented fifth, A5, from C to G#).
• Diminished Intervals: When a perfect or minor interval is decreased by one semitone, it becomes diminished (e.g., a diminished fifth, d5, from C to Gb).

Consonant vs. Dissonant Intervals

• Consonant Intervals: These intervals sound stable and pleasant. Perfect intervals (P1, P4, P5, P8) and some major and minor intervals (M3, m3, M6, m6) are considered consonant.
• Dissonant Intervals: These intervals create tension and seek resolution. Examples include minor seconds (m2), major sevenths (M7), and tritones (A4/d5).

Harmonic and Melodic Intervals

• Harmonic Intervals: Occur when two notes are played simultaneously, contributing to the harmony of a piece.
• Melodic Intervals: Occur when two notes are played in sequence, forming the foundation of melodies.

Interval Inversion

Intervals can be inverted by flipping the two notes. Inverting intervals changes their quality:

• Perfect Intervals remain perfect (e.g., P5 becomes P4).
• Major Intervals become minor (e.g., M3 becomes m6) and vice versa.
• Augmented Intervals become diminished (e.g., A4 becomes d5) and vice versa.

Why Understanding Intervals Matters

• Building Chords: Intervals are essential for understanding how chords are structured. For example, major and minor chords are built by stacking thirds.
• Creating Melodies: Melodies are composed of sequences of intervals. Knowing intervals helps musicians craft more compelling and cohesive melodies.
• Ear Training: Being able to recognize intervals by ear is vital for musicians. It helps with sight-reading, improvisation, and transcription.
• Harmonic Analysis: Understanding intervals allows musicians to analyze chord progressions and harmonic structures in pieces of music.

Conclusion

Intervals are the foundation of both harmony and melody. From the smallest, most dissonant minor second to the stable and consonant octave, intervals shape how we perceive music. By understanding these different intervals and their relationships, musicians can expand their ability to compose, perform, and analyze music.