Modulation using Diminished 7ths - Music Theory

Music Matters
14 Nov 201909:03
EducationalLearning
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TLDRThe video explains modulation in music, which is the process of changing from one key to another within a piece. It provides background, explaining how modulation adds interest and color. The video then focuses on the musical potential of the diminished 7th chord for modulations. It explains the chord's construction and how even small alterations to its notes open possibilities for smooth modulations to distant keys. The video advocates experimenting with diminished 7ths, through enharmonic changes, as a way for improvisers and composers to liven up pieces with exciting modulations.

Takeaways
  • 😀 Modulation is changing from one key to another within a piece of music.
  • 🎹 You can modulate to close keys on the circle of fifths, like the dominant or subdominant.
  • 🎵 In the 19th century, composers started modulating more adventurously using diminished 7ths.
  • 😮 A diminished 7th chord is built of minor 3rds (C Eb Gb Bbb).
  • 🔀 The diminished 7th chord can take you to several different keys by changing notes.
  • 🎼 Liszt used chains of diminished 7ths to create dramatic, bold modulations.
  • 🤯 By enharmonically changing notes in dim7 chords, you can modulate far from the original key.
  • 🎹 The dim7 in C major (B, D, F, Ab) could become Eb7 (Cb, Db, Fb, Abb) to modulate to Eb minor.
  • 😃 Conventional uses of dim7s add color; bolder uses help modulate between distant keys.
  • 🎵 Composers can use flexible dim7 chords to make more exciting, adventurous modulations.
Q & A

  • What is modulation in music?

    -Modulation is when we start in one key, and then move to another key. It adds variation and interest to a musical piece.

  • Why would a composer modulate to a close key in earlier periods of music?

    -In the Baroque and Classical periods, composers would usually modulate to a closely related key, such as the dominant, subdominant, or relative minor keys. This kept the music centered in a similar tonal area.

  • How did the use of modulation change in the 19th century?

    -In the 19th century, composers became more adventurous with modulation, moving quickly through distant keys or using diminished seventh chords to facilitate dramatic modulations.

  • What is a diminished seventh chord?

    -A diminished seventh chord is built by stacking minor thirds. For example, C Eb Gb Bbb forms a diminished seventh chord.

  • How can a diminished seventh chord be used to modulate?

    -By altering one or more notes of the diminished seventh chord enharmonically, it can resolve to different chords and key areas, allowing modulation to distant keys.

  • What are some keys a diminished seventh on B could resolve to?

    -With enharmonic spellings, a diminished seventh chord built on B could resolve to C major, A minor, D minor, or other keys.

  • How did Liszt use diminished seventh chords?

    -Liszt made extensive use of diminished seventh chords, frequently moving from one to another to create drama and harmonic instability in his music.

  • What happens with a Cb instead of B in the diminished seventh chord?

    -Using Cb instead of B means the diminished seventh could resolve to Eb minor, a dramatic modulation from the original C major.

  • Why are diminished seventh useful for modulation?

    -Diminished seventh chords have a symmetric structure that allows enharmonic respellings. This flexibility lets them resolve easily to several different keys to facilitate modulation.

  • Should modulation always sound chaotic?

    -No, a composer aims to make modulation sound smooth and purposeful, to creatively take the music into new tonal areas. Too many abrupt changes can sound chaotic.

Outlines
00:00
🎵 What is modulation and how it is used in music composition

This paragraph defines modulation as moving from one musical key to another within a composition. It explains that modulation adds interest and color. Traditionally modulation would move to closely related keys, but later composers became more adventurous. They used diminished 7th chords, which have flexible enharmonic spellings, to modulate more distantly. Liszt was known for his dramatic uses of chains of diminished 7ths to modulate rapidly through distantly related keys.

05:01
🎹 Using diminished 7th chords to modulate between musical keys

This paragraph further explains how a diminished 7th chord can be respelled enharmonically in different ways to modulate between distantly related keys. It shows examples starting in C major and modulating through respellings to A minor, D minor, and even the distant key of E-flat minor.

Mindmap
Keywords
💡modulation
Modulation refers to the process of changing from one key to another within a musical composition. As explained in the video, modulation adds interest and color to a piece, preventing it from sounding boring by staying in just one key. Examples of modulation in the script include moving from C major to G major or F major by adding or removing sharps/flats.
💡diminished seventh chord
A diminished seventh chord consists of four notes that are each a minor third apart, such as C Eb Gb and A. It creates a dramatic, tense sound. In the 19th century, composers realized this chord could be used in various ways to modulate between distant keys, by altering one or more notes enharmonically.
💡enharmonic alteration
An enharmonic alteration involves rewriting a note using its enharmonic equivalent to change its role or meaning within a key. For example, calling a note G# instead of Ab can allow a diminished seventh chord to resolve to an A major or minor chord, modulating the key in a smooth way.
💡dominant seventh chord
A dominant seventh chord consists of a major triad plus a minor seventh, such as G B D F in the key of C major. It has a strong tendency to resolve to the tonic chord. In the script, enharmonically altering part of a diminished seventh chord allows it to become a dominant seventh that resolves to a new key like Eb.
💡minor third
A minor third is an interval of three semitones between notes in a musical scale. Diminished seventh chords are formed by stacking four notes that are each a minor third apart, creating their tense and unstable sound which was useful for modulations in the 19th century.
💡circle of fifths
The circle of fifths shows relationships between major and minor keys, with closely related keys appearing next to each other. As described in the video, Baroque and Classical composers would modulate to closely related keys when changing tonal centers in a composition.
💡relative minor/major
Relative major and minor keys share the same key signature but have different tonic notes. For example, A minor is the relative minor of C major. Modulating between a key and its relative major/minor is a common technique as seen in the script.
💡subdominant
The subdominant chord (iv) in a key has a root a perfect fourth above the tonic - for example, F major in the key of C major. Composers would commonly modulate from a home key to its subdominant since it requires adding/removing only one accidental.
💡dominant
The dominant chord (V) in a key has a root a perfect fifth above the tonic - for example, G major in the key of C major. Modulating to the dominant key is a very common practice since just one new sharp or flat is introduced.
💡tonic
The tonic refers to the first scale degree in a key that represents the home or rest tone. It is the note and chord that melodies and harmonies tend to resolve towards for stability. C is the tonic in both the C major and C minor keys.
Highlights

Modulation is when we start in one key, and then move to another key

In Baroque/Classical music, composers would modulate to a close key like the dominant or subdominant

By the 19th century, composers wanted to modulate more adventurously and quickly through distant keys

The diminished 7th chord is built by stacking minor 3rds and has been used for drama in music

In the 19th century, composers realized the diminished 7th could help modulate between distant keys

By changing one note of a diminished 7th chord enharmonically, you can modulate to different keys

A diminished 7th in C major can modulate to A minor by changing the A-flat to G-sharp

The same diminished 7th can go to D minor by treating the B as C-flat which resolves to B-flat

So a single diminished 7th chord allows modulation between very distant keys like C major and E-flat minor

Liszt made great use of diminished 7ths to quickly modulate between dramatic, distant keys

Consider using diminished 7ths in composition/improvisation to creatively modulate

Can alter notes of a diminished 7th enharmonically to access different target keys

Diminished 7th belongs to the VII chord in a major or minor key

Often resolves conventionally to the I chord in a key for some color

So adds some interest before continuing in original key

Transcripts

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