Third

Definition

A third is a musical interval that spans three diatonic scale degrees. It plays a crucial role in constructing chords, such as triads and seventh chords, by determining their quality and character. The nature of the third—whether major or minor—affects the overall harmony and emotional expression in music.

5 Must Know Facts For Your Next Test

1. A major third consists of four half steps, while a minor third consists of three half steps, which gives each its unique sound and quality.
2. When constructing triads, the type of third (major or minor) used between the root and the third note defines whether the triad is major or minor.
3. In seventh chords, the third still plays an essential role, determining whether the chord has a major or minor quality based on the interval from the root to the third.
4. The interval of a third can also be inverted; for example, if a major third is inverted, it becomes a minor sixth when re-ordered.
5. Thirds can stack to create extended chords like ninths, elevenths, and thirteenths by continuing to add more thirds above the seventh chord.

Review Questions

• How does the quality of a third influence the type of triad that is formed?
  • The quality of a third is crucial in determining the type of triad created. A major third, which spans four half steps, paired with a perfect fifth forms a major triad. Conversely, when a minor third, spanning three half steps, is used with the perfect fifth, it results in a minor triad. This difference in intervals shapes the emotional character of the chord and influences how it resolves within musical contexts.
• Discuss how thirds are utilized in constructing seventh chords and their impact on harmonic progression.
  • In seventh chords, thirds are stacked on top of triads to create richer harmonies. The first interval forms a triad (major or minor), while an additional third is added above this triad to create the seventh interval. This arrangement enhances tension within harmonic progressions, allowing for smoother resolutions and more complex emotional expressions as they move towards stable chords.
• Evaluate how understanding intervals like thirds can aid in effective composition and arrangement in tonal music.
  • Understanding intervals such as thirds is fundamental for effective composition and arrangement in tonal music. By knowing how to manipulate these intervals to construct various chord types, composers can create distinct atmospheres and moods. Additionally, recognizing how different qualities of thirds contribute to tension and resolution allows composers to craft more engaging musical narratives, facilitating better emotional communication through their works.

Related terms

Triad: A triad is a three-note chord formed by stacking two thirds on top of a root note, typically consisting of the root, third, and fifth.

Seventh Chord: A seventh chord is a four-note chord that adds a seventh interval to a triad, creating additional harmonic richness and tension.

Diatonic Scale: A diatonic scale is a seven-note scale that includes five whole steps and two half steps, forming the basis for Western music harmony.