Mastering Secondary Dominants: Tonicization in Music Theory

Secondary dominants create tension by functioning as dominants of non-tonic chords. In 'All the Things You Are,' G7 serves as a secondary dominant pointing to C minor (iii degree of A-flat), then resolves to C major. This demonstrates how secondary dominants facilitate smooth modulations between keys. The song employs multiple modulations including A-flat to C major (major third), C to E-flat, and E-flat to G major, each using secondary dominants as pivot points.

A pivot chord is a chord belonging to both the original and target key, serving as a transitional 'door' between harmonic spaces. When starting in C major, the three most closely related keys are G major (dominant), F major (subdominant), and A minor (relative minor). For modulation to G major, pivot chords include I (C = IV in G), III (E minor = VI in G), V (G = I in G), and VI (A minor = II in G). For modulation to F major, pivot chords include I (C = V in F), II (D minor = VI in F), IV (F = I in F), and VI (A minor = III in F). The pivot chord typically appears at the end of the first bar for dominant modulation and at the beginning of the second bar for subdominant modulation, followed by accidentals establishing the new key.

Common chord modulation, also called pivot chord modulation, uses a chord shared between the original and destination key as a bridge or 'door' between tonal centers. This technique can modulate between any combination of major and minor keys. Most common chord modulations occur between closely related keys—keys positioned adjacent on the circle of fifths that share many common chords. For C major, closely related keys are F major, G major, D minor, A minor, and E minor (including the related minor keys). While closely related keys are the obvious choice, more distant keys create more dramatic changes. To successfully modulate, both the original and destination keys must be established. The easiest method uses tonic-predominant-dominant progression: tonic, predominant (second degree), dominant (fifth degree), returning to tonic. A pivot chord is a shared chord that typically functions as predominant in the destination key, leading to its dominant chord.

A pivot chord is a chord that exists in both the original key and the target key, serving as a bridge or 'door' between them during modulation; in major keys, composers can modulate to five closely related neighboring keys (the tonic's dominant, subdominant, and their relative minors) by identifying shared chords between the keys and introducing the necessary accidentals to confirm the new key, with pivot chord options varying based on the specific key relationship (e.g., from C major to F major, pivot chords include I, III, V, and VI).

Secondary dominant chords create tension that resolves to a target chord, and can be used to modulate to new keys. The dominant and subdominant chords are particularly important in this process. By using these chords strategically, musicians can create smooth transitions to new keys, often used in choruses to build excitement and anticipation.

Modal interchange, also known as borrowed chords or modal mixture, is a harmonic technique where non-diatonic chords are borrowed from a parallel key (a key that shares the same tonic note but has different notes, such as C major and C minor) to add harmonic variety to a chord progression; this technique involves temporarily moving away from the key center before resolving back to the original key, with common examples including borrowing the ii chord (D half-diminished) or iv chord (F minor) from the parallel minor scale in a major key context.

Modal mixture allows musicians to write chromatic-infused chord progressions by borrowing chords from parallel modes; for example, in a major key, you can descend chromatically from the tonic to the dominant by borrowing chords from the parallel minor scale (such as B diminished, B flat, and A flat chords in C major), while in minor keys, you can incorporate notes from the harmonic minor and Dorian scales to create chromatic bass lines that sound elegant and sophisticated.

The Neapolitan chord (built on the lowered supertonic, e.g., D♭ in C major) is a chromatic chord that can be used to modulate dramatically to a key five flats away (such as from C major to D♭ major), providing a more adventurous modulation technique than traditional methods.

Borrowed chords (also called modal interchange or modal mixture) are a reharmonization technique where musicians temporarily borrow chords from parallel modes or keys outside the diatonic key, creating richer harmonic colors while still returning to the original key center; for example, in C major, one might borrow a D half diminished chord from C minor (the parallel minor) or a D7 chord from C Lydian, distinguishing this technique from modulation which involves a longer stay in a new key.

This segment explains modal mixture—the practice of borrowing chords from parallel modes—to add harmonic sophistication. The instructor demonstrates how Johan Kim borrows from D minor to use chords like F# minor 7 flat 5 (the 7 chord of G or 2 chord of E minor) and Bb major 7. These borrowed chords create tonal ambiguity and unique harmonic colors characteristic of gospel music, expanding the harmonic palette beyond the diatonic scale.

In four-part voice leading, chord construction follows specific rules: use the middle range of each voice for balance, double the root in root-position triads but avoid doubling tendency tones (leading tones and sevenths); every chord needs a root and third to define its quality, though fifths can occasionally be omitted; maintain no more than an octave between upper voices and avoid voice crossing, while distinguishing between close position (no space between chord tones) and open position (space exists between chord tones).

This video covers the essential rules of part writing for four-voice textures. Two main textures exist: chorale style (SATB) with soprano/alto on treble clef and tenor/bass on bass clef, and keyboard style with three voices on treble and one on bass. Each voice has a range of about a tenth with endpoints as C major triad notes. Spacing requires an octave or less between adjacent upper voices. Avoid parallel perfect fifths and octaves, but parallel fourths are acceptable. Voice leading rules depend on chord root intervals: move upper voices in contrary motion when roots differ by second, retain common tones when roots differ by third/sixth, and retain common tone when roots differ by fourth/fifth. Double the root in 99% of cases, except for incomplete five-seven chords (double/triple root) and seven diminished chords (double third). Tendency tones include the leading tone (scale degree 7) which must resolve to tonic if in outer voice, and scale degree 4 which is only strong when paired with scale degree 7.

In four-part harmony, voice leading requires understanding five types of motion between voices: static (no movement), oblique (one voice moves while another stays), similar (both move in same direction by different intervals), contrary (one moves up while another moves down), and parallel (both move in same direction by same interval). Parallel unisons, fifths, and octaves are problematic because they eliminate melodic independence, making voices sound like a single combined melody rather than independent lines. Direct and hidden fifths/octaves occur when outer voices (soprano and bass) move in similar motion into a perfect fifth or octave with a leap in the soprano. Unequal fifths (diminished fifth resolving to perfect fifth) are also problematic. Voice leading errors can be identified by examining all six voice pairings (soprano-alto, soprano-tenor, soprano-bass, alto-tenor, alto-bass, tenor-bass) for each chord progression, ensuring that independent melodies are maintained throughout the composition.

Voice leading technique reaches perfection in Baroque music and follows specific rules. The goal is achieving maximum independence for each voice, allowing each to have its own melodic sense. Four-voice chord construction requires specific interval distances: bass and tenor can reach up to a tenth or eleventh, while tenor-alto and alto-soprano distances should not exceed an octave. Desired movements include contrary motion, parallel thirds and sixths, and lateral movements. The first harmonic rule requires sensitive voices in dominant resolution to move by the shortest path.

Proper voice leading requires thinking of four voices as three plus one rather than two plus two. Large spaces between alto and tenor create poor texture and make the tenor too low. Maintain no more than an octave between neighboring parts except tenor-bass. Bach frequently uses passing notes to create seventh chords, adding tension that resolves to the next chord. Shared notes between chords create smooth part writing and stability.

The instructor analyzes the song 'Evidências' to demonstrate practical application of secondary dominants. The song uses multiple secondary dominants including D7 (leading to F), A7 (leading to Dm), and others. The instructor shows how these chords create tension and resolution throughout the piece, making the music more emotionally engaging. The demonstration includes playing the song with and without secondary dominants to illustrate the difference in musical impact.

Adding secondary dominance in front of every chord in a progression gives each chord so much extra weight—it's like a high-definition version of the classic 1-6-2-5 progression. Secondary dominants are about as fundamental of a technique as it gets. They can be effective in so many different genres of music: pompous classical themes, ragtime jazz, funky grooves, and everything in between. They're all used about the same way but each one has a different personality and evokes a slightly different atmosphere. If you're trying to break out of strictly inside-the-key writing, secondary dominance is highly recommended as a starting point.

Secondary dominants can be applied to any song by inserting the dominant preparation before the target chord. For example, in a song in C major going to A minor, insert E7 before A minor; going to F major, insert C7 before F; going to D minor, insert A7 before D minor. This technique enriches harmonies and creates more sophisticated musical arrangements. Developing musical taste requires experimenting with secondary dominants, listening to how they sound, and understanding when they work well. This process helps musicians demystify harmonic structures and develop their ear for sophisticated chord progressions.

In music theory for songwriters, borrowed chords are chords taken from the parallel minor key (sharing the same tonic) that add harmonic color to major key compositions, such as the flat third major chord (C major in A major) and flat sixth/fifth major chords (F major and G major in A major); secondary dominant chords are dominant seventh chords that lead to other chords in the key (like F#7 leading to Bm or C#7 leading to F#m), creating tension and resolution that enhances songwriting by providing common progressions like I to flat three major to four major to four minor, which features the powerful leading tone effect where the third of the borrowed chord resolves up a half step to the fourth chord.

The instructor explains secondary dominants, which are chords that tonicize (make sound like a new key) a chord that is already diatonic to the key center. In Autumn Leaves, G7 alt is a secondary dominant that resolves to C minor 7. It is called the '5 of 2' because C minor 7 is the 2 chord. The instructor explains that secondary dominants create tension and resolution, which is essential in jazz improvisation. Musicians often add secondary dominants to create more tension and resolution in their jazz lines.