Lecture Notes: Triads and Dominant Seventh Chords in Major Keys

Introduction

• Discussion on triads and dominant seventh chord in major keys.
• Relationship to Roman numerals and figured bass.
• Focus on harmonic analysis.

Triads

• Definition: Chords with two superimposed thirds.
• Example: Build triads in C major using only white keys (notes without accidentals).
  • C major key signature: no accidentals.
• Building Triads: On each of the seven scale degrees.

Dominant Seventh Chord

• Commonality: Customarily built on the fifth scale degree.
• Usage: Replaces the dominant triad.
• Generally, seventh chords are not built on other scale degrees in traditional music theory.
  • Example: C major triad C, E, G - adding B is dissonant, would need resolution.
• Half-diminished seventh chord: Sometimes built on the leading tone, more common in minor keys.

Characteristics of Triads in Major Keys

• Qualities:
  • Tonic, Subdominant, Dominant: Major
  • Supertonic, Mediant, Submediant: Minor
  • Leading Tone: Diminished
• Seventh chord on Dominant: Always a dominant seventh chord.
• Consistency across major keys: Once known for one key, applicable to all.

Roman Numerals and Figured Bass

• Key Indication: Uppercase letter for major keys.
• Use of Roman numerals to indicate chord qualities and positions:
  • Uppercase: Major chords
  • Lowercase: Minor chords
  • Lowercase with superscript O: Diminished chords
  • Dominant seventh indicated with V and superscript VII.

Example: F Major

• Roman Numerals: Show chord qualities (1, 4, 5 as major; 2, 3, 6 as minor; 7 as diminished).
• Application: Show chords on scale degrees with inversions, using figured bass.

Harmonic Analysis Process

1. Identify Notes: Tally notes for each chord.
2. Cross Out Doublings: Identify three or four note names.
3. Arrange as Thirds: Determine root by stacking thirds.
4. Determine Quality: Use thirds and sevenths to determine chord quality.
5. Relate to Key: Identify scale degree of root.
6. Figured Bass: Add if triads are inverted.

Example Analysis

• Chorale by Bach:
  • Non-harmonic tones circled (e.g., passing tones).
  • Use of quarter note harmonic rhythm.
• Steps for Analysis:
  • Identify root position and inversions.
  • Determine the progression using Roman numerals.

Conclusion

• Transition to upcoming discussion on chords in minor keys.