In tonal music, there are two classes of intervals – dissonant and consonant intervals. If you missed the lesson on Consonant Intervals (plus the free 111-pg guide), be sure to go through it.
In this article, we’ll focus on the evolution in music and its effect on dissonant intervals.
Consonance
When intervals sound pleasant and agreeable, they are said to be consonant. Following traditional guidelines, the following intervals are associated with consonance:
Perfect Consonance
- Perfect Unison/Octave
- Perfect 4th
- Perfect 5th
Imperfect Consonance
- Major 3rd
- Minor 3rd
- Major 6th
- Minor 6th
Dissonance
When intervals sound unpleasant and disagreeable, they are said to be dissonant. These intervals possess a high (or low) degree of tension and have the tendency to resolve to consonant intervals. Following traditional guidelines, the following intervals are associated with dissonance:
Diatonic Dissonance
- Major 2nd
- Minor 2nd
- Major 7th
- Minor 7th
Chromatic Dissonance
- Augmented 4th and ALL Augmented Intervals
- Diminished 5th and ALL Diminished Intervals
Evolution
I’m not an evolutionist like Charles Darwin and his disciples. However, I believe that evolution is an integral part of humanity. Life is dynamic in diverse ways. So many things that were outrageous years ago are beginning to gain acceptance. Evolution has affected different facets of our life. Let’s consider some of the facets:
#1 – Religion
There was a time when terrorism was just a dictionary word and condemned by all religious bodies. In recent times, terrorism has gained grounds. There are religious sects that have openly embraced terrorism like the Boko Haram sect in Nigeria.
#2 – Fashion
There was a time when indecent dressing was condemned by all. Everyone publicly shunned those who exposed certain parts of their body. Today, the story is different. Fashion has evolved, exposure of certain body parts is in vogue.
#3 – Moral Standards
Moral standards are declining. Societies that condemned prostitution and other vices are turning around to promote them. Several nations have passed bills to legalize prostitution or even drug use.
#4 – Marriage
Gone are the days when the war against same-sex marriage was fought by all. Today, same-sex marriage is legalized in different parts of the world.
#5 – Harmony
There was a time when certain intervals were avoided because of their dissonant property. The diminished 5th interval was considered to be extremely dissonant. In the 18th century, it was banned. Today, the story is different. Jazz and Gospel Musicians (and musicians in other styles of American popular music) have made this interval an integral part of harmony.
Yesterday: Discords resolve to concords. E.g. – Gdom7 (a discord) resolves to C Major Triad.
Today: Discords no longer resolve. E.g. Gdom7 can be used as the tonic chord in the key of G.
This does not mean that the dissonant property of this discord has diminished – not at all.
In the bebop era, Jazz musicians took dissonance to another level. The following innovations were made:
Exploration of altered extensions of the dominant chord. This perspective heightened dissonance using compound intervals like:
- ♯9 – Augmented Ninth
- ♭9 – Minor Ninth (This is arguably the most dissonant interval in Jazz. It exists between the 3rd and 11th and up until now, Jazz musicians have avoided the use of the natural eleventh. This is because it forms a minor 9th from the third.)
Simple intervals weren’t left out:
- ♯5 – Augmented Fifth
- ♭5 – Diminished Fifth (Diaboli Musica – Devil in Music)
Substitution of chords related by the tritone progression. There are twelve dominant chords in tonal music:
- C Dom7
- C♯/D♭ Dom7
- D Dom7
- D♯/E♭ Dom7
- E Dom7
- F Dom7
- F♯/G♭ Dom7
- G Dom7
- G♯/A♭ Dom7
- A Dom7
- A♯/B♭ Dom7
- B Dom7
Dominant chords that are a tritone progression apart were used as mutual substitutes (aka – “Tritone substitutions.”) E.g. – G Dom7 to C Maj7 became C♯/D♭ Dom7 to C Maj7.
|
Chord |
Tritone Substitution |
|
C Dom7 |
F♯/G♭ Dom7 |
|
D Dom7 |
G♯/A♭ Dom7 |
|
E Dom7 |
A♯/B♭ Dom7 |
|
G Dom7 |
C♯/D♭ Dom7 |
|
A Dom7 |
D♯/E♭ Dom7 |
|
B Dom7 |
F Dom7 |
Superimposition of chords to create polychords. This is the use of triads and seventh chords over dominant chords to create polychords. A polychord is the superimposition of two or more chords.
Examples:
E / G Dom7
E♭ / G Dom7
D♭ / G Dom7
Yesterday and Today
YESTERDAY: Certain classes of chords that were forbidden several centuries ago because of their extreme dissonance, (e.g. – the G Dom 7), cannot move a grain of sand today. Therefore, it is important to evolve with the music. Don’t stick to the regular dominant seventh chord (simply because it is traditionally considered dominant) when there are 20th century ideas from the bebop era (like the ones I shared) that can heighten its dissonance.
TODAY: Music has evolved to the point where dominant 7th chords can be resolved or not. Therefore, if you must play something dissonant, play it better than it was played years ago. This is because musical tastes have evolved beyond the harmonic provisions of the dominant seventh chord.
Until next time.
Chuku Onyemachi
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