🎶AP Music Theory Unit 3 – Triads and Seventh Chords

What Are Triads?

• Triads are chords consisting of three notes stacked in thirds
• The bottom note is called the root, the middle note is the third, and the top note is the fifth
• Triads are built on a specific scale degree and use notes from that scale
• Can be played in root position or inverted (more on inversions later)
• Triads are the foundation of harmony in Western music
• Triads have a distinct sound based on the quality of the intervals between the notes
  • Major triads have a bright, happy sound (C Major: C-E-G)
  • Minor triads have a darker, melancholic sound (A Minor: A-C-E)

Types of Triads

• There are four main types of triads: major, minor, diminished, and augmented
• Major triads consist of a major third and a perfect fifth above the root (C-E-G)
• Minor triads have a minor third and a perfect fifth above the root (A-C-E)
• Diminished triads contain a minor third and a diminished fifth above the root (B-D-F)
  • Diminished triads have a tense, unstable sound
• Augmented triads have a major third and an augmented fifth above the root (C-E-G#)
  • Augmented triads have a bright, but slightly unsettling sound
• The quality of a triad is determined by the intervals between the root, third, and fifth

Triad Inversions

• Triads can be played in three different positions: root position, first inversion, and second inversion
• Root position has the root note as the lowest note (C-E-G)
• First inversion has the third as the lowest note (E-G-C)
  • First inversion triads are often used to create smooth voice leading
• Second inversion has the fifth as the lowest note (G-C-E)
  • Second inversion triads are less stable and often used as passing chords
• Inversions are labeled with figured bass symbols (root position: 5/3, first inversion: 6/3, second inversion: 6/4)
• Inverting a triad changes the bass note but maintains the quality of the triad

Introduction to Seventh Chords

• Seventh chords are created by adding a seventh above the root of a triad
• There are five main types of seventh chords: major seventh, dominant seventh, minor seventh, half-diminished seventh, and fully-diminished seventh
• Seventh chords add more complexity and tension to harmony compared to triads
• The quality of the seventh (major, minor, or diminished) determines the overall sound and function of the chord
• Seventh chords are commonly used in jazz, but also appear in classical, pop, and rock music
• Seventh chords can be resolved to other chords to create harmonic progression

Types of Seventh Chords

• Major seventh chords consist of a major triad with a major seventh above the root (Cmaj7: C-E-G-B)
  • Major seventh chords have a bright, jazzy sound and often serve as tonic chords
• Dominant seventh chords have a major triad with a minor seventh above the root (C7: C-E-G-Bb)
  • Dominant seventh chords create a strong pull towards the tonic and are used in authentic cadences
• Minor seventh chords contain a minor triad with a minor seventh above the root (Cm7: C-Eb-G-Bb)
  • Minor seventh chords have a dark, complex sound and often serve as ii or vi chords in a progression
• Half-diminished seventh chords have a diminished triad with a minor seventh above the root (Bø7: B-D-F-A)
  • Half-diminished seventh chords have a tense, unresolved sound and often function as vii chords in minor keys
• Fully-diminished seventh chords consist of a diminished triad with a diminished seventh above the root (Bdim7: B-D-F-Ab)
  • Fully-diminished seventh chords have a very tense, unstable sound and are often used as passing chords

Seventh Chord Inversions

• Like triads, seventh chords can be inverted to create different voicings and bass notes
• Seventh chords have four possible positions: root position, first inversion, second inversion, and third inversion
• Root position has the root as the lowest note (Cmaj7: C-E-G-B)
• First inversion has the third as the lowest note (Cmaj7/E: E-G-B-C)
• Second inversion has the fifth as the lowest note (Cmaj7/G: G-B-C-E)
• Third inversion has the seventh as the lowest note (Cmaj7/B: B-C-E-G)
  • Third inversion seventh chords are the least stable and often resolve to other chords
• Inverting seventh chords can create smoother voice leading and add variety to chord progressions

Chord Progressions with Triads and Sevenths

• Triads and seventh chords are the building blocks of chord progressions in Western music
• Common chord progressions include I-IV-V, ii-V-I, and I-vi-IV-V
  • In the key of C, I-IV-V would be C-F-G
• Seventh chords can be substituted for triads to add complexity and tension to a progression
  • In the key of C, I-IV-V with sevenths would be Cmaj7-F7-G7
• Chord progressions often follow functional harmony rules, with chords serving specific roles (tonic, subdominant, dominant)
• Cadences are specific chord progressions that provide a sense of resolution or tension
  • Authentic cadences (V-I) create a strong sense of resolution
  • Deceptive cadences (V-vi) create tension and surprise
• Analyzing chord progressions can help understand the harmonic structure and emotional content of a piece

Applying Triads and Sevenths in Music Analysis

• Identifying triads and seventh chords is a crucial skill in music analysis
• When analyzing a piece, first determine the key and then identify chords based on their scale degrees
  • In the key of C, a triad built on the second scale degree (D-F-A) would be a ii chord (Dm)
• Pay attention to chord qualities (major, minor, diminished, augmented) and how they function in the progression
• Analyze how chord inversions are used to create smooth voice leading or highlight specific notes
• Look for common chord progressions and cadences to understand the harmonic structure of the piece
• Consider how the use of triads and seventh chords contributes to the overall emotional content and style of the music
  • Dominant seventh chords in a blues progression create a sense of tension and release
  • Lush major seventh chords in a jazz ballad evoke a romantic, sophisticated mood
• Comparing the use of triads and seventh chords across different genres and time periods can provide insights into the evolution of harmony in Western music