🎶AP Music Theory Unit 4 – Chord Function, Cadence, and Phrase

Key Concepts

• Chord function refers to the role a chord plays within a musical phrase or progression
• Cadences are specific chord progressions that provide a sense of resolution or closure at the end of a phrase
• Phrases are musical units that typically consist of four or more measures and end with a cadence
• Harmonic analysis involves identifying the chords and their functions within a piece of music
• Common chord progressions include I-IV-V-I, ii-V-I, and iii-vi-ii-V-I
  • These progressions are frequently used in various musical styles and genres
• Understanding chord function, cadence, and phrase structure is essential for composing, arranging, and analyzing music

Chord Types and Functions

• Tonic chords (I and vi) provide a sense of stability and resolution
  • The tonic chord is the most important chord in a key and is often used to begin and end phrases
• Subdominant chords (IV and ii) create a sense of departure from the tonic and often lead to the dominant chord
  • These chords are frequently used in the middle of a phrase to build tension
• Dominant chords (V and vii°) create a strong pull towards the tonic and are used to create tension and resolution
  • The dominant chord is the second most important chord in a key and is often used before the tonic chord
• Leading-tone chords (vii° and iii) contain the leading tone and have a strong tendency to resolve to the tonic
• Mediant chords (iii and vi) can function as tonic substitutes or provide contrast within a progression

Cadence Types and Uses

• Authentic cadences (V-I or V7-I) provide a strong sense of resolution and are often used at the end of a phrase or piece
  • Perfect authentic cadences (PAC) occur when the melody ends on the tonic note and the chord progression is V-I
  • Imperfect authentic cadences (IAC) occur when the melody ends on a note other than the tonic or the chord progression is V-vi
• Plagal cadences (IV-I) provide a sense of resolution but are less conclusive than authentic cadences
  • These cadences are often used in religious music (Amen cadence) or as a secondary cadence following an authentic cadence
• Half cadences (I-V or IV-V) create a sense of incompleteness and are often used in the middle of a phrase
  • These cadences are useful for creating tension and anticipation before resolving to the tonic
• Deceptive cadences (V-vi) create a sense of surprise by resolving to the submediant instead of the expected tonic
  • These cadences can be used to extend a phrase or create a sense of uncertainty

Phrase Structure

• Antecedent phrases are the first half of a period and typically end with a weak cadence (IAC or HC)
  • These phrases often present a musical idea or question that requires a response
• Consequent phrases are the second half of a period and typically end with a strong cadence (PAC)
  • These phrases provide a response or resolution to the antecedent phrase
• Periods are complete musical thoughts consisting of an antecedent and consequent phrase
  • Periods are often 8 measures long (4+4) but can be extended or shortened
• Phrases can also be classified as parallel or contrasting based on their melodic and harmonic content
  • Parallel phrases have similar melodic and harmonic content, while contrasting phrases have different content

Harmonic Analysis

• Identify the key of the piece by looking for cadences and the tonic chord
• Label each chord with Roman numerals (I, ii, iii, IV, V, vi, vii°) based on its scale degree in the key
  • Use uppercase numerals for major chords and lowercase for minor chords
  • Use a degree symbol (°) for diminished chords and a superscript 7 for seventh chords
• Identify the function of each chord (tonic, subdominant, dominant, etc.) based on its scale degree and context
• Analyze the chord progressions and identify any common patterns or cadences
• Consider the melodic content and how it interacts with the harmony to create phrases and periods

Common Chord Progressions

• I-IV-V-I is a common progression used in many genres, including rock, pop, and folk music
  • This progression establishes the tonic, moves to the subdominant, then the dominant, and resolves back to the tonic
• ii-V-I is a common jazz progression that creates a sense of tension and resolution
  • The ii chord functions as a subdominant, the V chord as a dominant, and the I chord as the tonic resolution
• I-vi-IV-V is a variation of the I-IV-V-I progression with the addition of the submediant chord
  • This progression is often used in pop and rock music (Heart and Soul progression)
• iii-vi-ii-V-I is a longer progression that incorporates more chords and functions
  • This progression includes the mediant (iii), submediant (vi), supertonic (ii), dominant (V), and tonic (I) chords

Practical Applications

• When composing music, use chord functions and cadences to create a sense of structure and resolution
  • Use tonic chords for stability, subdominant chords for departure, and dominant chords for tension and resolution
  • Use authentic cadences for strong endings and half cadences for mid-phrase tension
• When arranging music, consider how different chord voicings and inversions can affect the overall sound and function
  • Use inversions to create smoother voice leading and to emphasize different notes in the melody
• When analyzing music, identify the key, chord functions, and cadences to understand the structure and emotional content
  • Look for common chord progressions and how they are used to create phrases and periods
• When performing music, be aware of the chord functions and cadences to create a sense of phrasing and expression
  • Emphasize the tension and resolution created by different chord functions and cadences in your playing or singing

Advanced Topics

• Secondary dominants are dominant chords that resolve to a chord other than the tonic
  • These chords are often used to create additional tension and interest within a progression
  • Examples include V/ii (read as "five of two"), which is the dominant chord of the supertonic (ii)
• Modulation is the process of changing from one key to another within a piece of music
  • Modulations often occur at phrase boundaries and can be achieved through the use of pivot chords or secondary dominants
• Borrowed chords are chords that are "borrowed" from the parallel major or minor key
  • These chords can add color and variety to a progression and are often used in romantic and impressionistic music
• Neapolitan chords (bII) are major chords built on the lowered second scale degree
  • These chords function as subdominants and often lead to the dominant chord
• Augmented sixth chords (It+6, Fr+6, Ger+6) are chromatic chords that resolve to the dominant
  • These chords are named after their interval structure and are often used in classical and romantic music