Want to know about the leading tone triads, 7th chords, and the secondary leading tone triads and seventh chords?
Leading tone chords are unstable chords urging for resolution upwards due to the presence of 7th, 2nd, and 4th scale degree tones. In addition, they have a tritone, which is itself a dissonant interval.
In this article, we will deal with all the intricacies associated with the leading tone, types of leading tone chords, their function, and voice leading. This will be followed by an introduction to secondary functions, secondary leading tone chords, rules for their use, spelling, analysis, voice leading, progressions, and much more.
Read the complete article to know about these topics thoroughly.
What is a Leading Tone?
In Western music theory, a pitch or a note that has a strong urge to resolve either a half step up or down is called a leading tone, also known as the subsemitone or the leading note. Based on whether the resolution is up or down a semitone, the leading tone is known as a lower or upper leading tone.
What we commonly encounter in a major scale is a leading tone that resolves upwards to the octave and lies at the seventh scale degree. In common parlance, most people refer to these notes simply as the leading tone. In the C major scale, B is the seventh scale degree note forming the leading tone.
Examples of leading note resolving down includes a lowered second degree, a minor 2nd resolving to the tonic, or a b6 note resolving to the dominant note. You will encounter b2 scale degree notes in Neapolitan and augmented 6th chords.
In minor and other scales like the Mixolydian, the seventh note is a whole tone below the octave and is known as the subtonic. A raised 7th is often used during cadences in many of these cases leading to a harmonic minor scale.
In major scales, the intervals of the scale degree 7, 4, and 2 notes with respect to the tonic note are the most unstable, dissonant, and unbalanced and point to 1(8), 3, and 1 scale degrees for resolution.
Learn about Leading Note Chords and How they are Applied?
In the next few sections, you will learn about the leading note chords, their formation and structure, and their application in chord progressions.
The chords built on the vii degree of a major key and the raised seventh degree of a harmonic minor scale are known as the leading tone chords.
Types of Leading Tone Chords
You can begin by familiarizing yourself with the types of chords built on the leading note.
Leading Tone Triad (LTT)
The leading tone triad in a major scale is designated as viio and is a diminished chord. In the key of C, B diminished triad with note names [B D F] is the leading tone triad. In the C harmonic minor scale also, B is the LTT. The presence of the tritone makes it a dissonant chord with a strong tendency to resolve to the tonic triad.
Functions of A Leading Tone Triad (LTT)
The leading tone triads take up many functions, as listed below:
- Act as a passing chord between the tonic triad in the root position and its first inversion. This means that VII6 is a passing chord between I and I6.
- It forms a neighboring chord to I or I6.
- In both the above cases, it prolongs the tonic by carrying out the passing and the neighboring function.
- You can refer to the LTT as the incomplete form of the dom7, the dominant 7th chord. You may know that an incomplete chord in classical music has its root note omitted. The dom7 chord is formed by [5, 7, 2, and 4] scale degrees in a major key. The viio chord is formed by [7, 2, 4]. Hence the presence of the dominant function.
Voice Leading of LTT
- It is only used in its 1st inversion to have a better voice leading. The leading tone must resolve to the tonic, unlike in a dominant chord, where it does not resolve to the tonic if it is in the inner voice.
- The tritone interval – If written as a diminished 5th, it resolves inward, and if written as an augmented 4th interval, it resolves outwards.
- If a four-part voice is required, the third note is double instead of the root, unlike other major or minor chords.
Leading Tone Seventh Chords
As you would have guessed, the leading tone 7th chords are the half-diminished 7th and fully diminished chords, built with the seventh tone of the major and harmonic minor scale as the root, respectively. These chords were not a part of renaissance music but have been used in the Baroque and classical periods. They find more use in ragtime, contemporary popular, and jazz.
These two chords are discussed next.
Half Diminished Seventh Chord
The half-diminished 7th chord denoted by viiø7 is formed by stacking a major 3rd interval over the diminished triads. These chords are built naturally from the pitches of any major scale. In C major, the viiø7 chord has the notes [B D F A].
Fully Diminished Seventh Chord
The fully diminished leading tone seventh chord is built from the 7th degree of the harmonic minor key. In C minor, the viio7 chord has the notes [B D F Ab]. Composers may use a modal mixture, where they substitute this chord in place of the half-diminished seventh chord, as you will see later in the sections on the secondary leading tone seventh chords.
Functions of A Leading Tone 7th Chord (LTSC)
The main functions of an LTSC are:
- They exhibit dominant functions and are used frequently in place of V or V7 chords for variety.
- They can be considered dom9 chords without the root.
Voice Leading of LTSC
- The LT 7th chords mostly feature in their root position.
What is a Secondary Function?
You were introduced to the secondary function in our article on secondary dominants. Both the secondary leading tone and secondary dominant chords serve the same function of tonicizing or emphasizing any chord of the key by the use of an altered chord. This effectively means any chord which can be emphasized by the secondary dominants can also be tonicized by the SLTC.
You may recall that the secondary functions can be used to tonicize only the major and minor triads.
What is a Secondary Leading tone?
The secondary leading note for any scale degree in major or minor keys (other than scale degrees resulting in diminished and tonic chords) is a chromatic note formed by lowering them by a semitone.
Secondary leading Tone (SLT) Chords
No marks for guessing that the SLT chords are formed with the secondary leading note as their root. This means tonicizing any minor or major chord requires you to find the secondary leading note associated with it and build a chord with the SLT as the root.
For example, if we want to tonicize G, the V chord in the key of C, the SLT is F# for G, which is a half step lower than G. F# is not in the key of C major. A chord formed with F# as its root [F# A C] is the SLT chord.
Types of SLT Chords
The SLT chords can be of three types, the same as the normal leading tone chords as listed below:
- Diminished triad denoted as viio.
- Half Diminished 7th chords, viiø7.
- Full diminished 7th chords, viio7.
The SLT chords themselves are designated as viio/iv, viiø7/VI, or viio7/III. This is the same representation as the one used for secondary dominants. Only the type of SLT chord replaces the type of V chords in the symbols.
Rules for the Use of SLT chords
The next question is where each of the above types can be used. You may note the below rules for the purpose:
- If you are tonicizing a major triad, you can use any one of the three.
- For a minor chord tonicization, you should not use the half-diminished 7ths, viiø7. You can use viio or viio7.
- There is no (viio/III) chord in a minor key, as this is the same chord as iio.
- Due to the same reason, there is no viiø7/III in a minor scale, as it matches the notes of iiø7.
- There is no viiø7/V in a minor key, as the V chord is made as a major chord using the harmonic scale instead of the natural minor. You can use viio/V or viio7/V.
Spelling A Secondary Leading Tone Chord
The procedure for spelling an SLT chord is as follows:
- State the root of the chord you may like to tonicize.
- Go down a minor 2nd interval or a half step.
- Use that note as the root to spell a viio, viiø7, or viio7 chord, as needed.
Examples of Building an SLT chord
Example: Find the viio/IV, viiø7/IV, and viio7/IV for the key of C.
Solution: The solution is given in the steps below.
- The IV scale degree in C is F. The IV chord to be tonicized is F major.
- One semitone below F is E.
- The viio/IV, viiø7/IV, and viio7/IV chords are [E G Bb], [E G Bb D], and [E G Bb Db].
Identifying or Analyzing a Chord with a Secondary Leading Tone (SLT)
The steps for identifying or analyzing SLT chords are as follows:
- Check if there is an altered viio, viiø7, or viio7 chord in the progression.
- Find a note that is a minor 2nd interval or a half step above the root of this altered chord.
- Is it possible to build a minor or a major chord with that note in the present key?
- If yes, the altered key is tonicizing the chord in step 3.
Examples of Analyzing an SLT chord
Example: Analyze the chord [G# B D F] in C.
Solution: The solution is given in the steps below.
- The given chord is an altered chord as G# is chromatic. It is a fully diminished chord.
- The note half step above G# is A.
- We can build A minor chord, vi, with this note.
- Hence the given chord, G#o7, is the viio7/vi chord.
Chord Progressions Using Secondary Leading Tones
Consider a progression: vi – viiø7/V – I6/4 – V7 – I
In C: the above example has chords – Am – F#ø7 – C/G – G7 – C.
C/G is the second inversion of the C chord, with G as the bass note. Hence F#ø7 secondary leading tone chord leads to C/G and eventually the I chord through the G7 chord.
Another example is V7 – viio7/vi – vi – V6/5 – I.
In D: it is A7 – A#07 – Bm – A7/C# – D
Notice that the progression is going up in half or whole steps in root notes up to D. From A to A# to B to C# to D. The SLT chord provides the color and allows the composers to do more in melody above this chord.
Voice Leading of the SLT chords
The voice leading of the SLT happens by
- The 7th note of the leading tone seventh chord resolves down.
- The leading tone in the chord resolves up.
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