Music 101: What Is Harmony and How Is It Used in Music?

Harmony is the composite product when individual musical voices group together to form a cohesive whole. Think of an orchestra: the flute player may be playing one note, the violinist plays a different note, and the trombonist plays yet a different note. But when their individual parts are heard together, harmony is created.

Harmony is typically analyzed as a series of chords. In that hypothetical orchestra, let’s say that the flutist was playing a high A, the violinist bowed a C#, and the trombonist sustained an F#. Together, those three notes comprise an F# minor triad. Therefore, even though each instrumentalist was only playing a single note, together they played an F# minor chord.

• When all the instruments in an ensemble are playing notes that fit the same chord, it is known as a consonant chord.
• But when players employ a melodic line that does not fit with a set chord (such as an oboist playing a Bb when the rest of the orchestra is playing the tones of a D major triad), it is known as a dissonant chord.
• This isn’t to say that some harmonies aren’t intentionally dissonant. Perhaps the composer of that hypothetical piece wanted to hear a Bb over a D chord (in terms of music theory, the note’s harmonic function would be the flat 6th scale degree), even though it wouldn’t be the most pleasing combination to most fans of Western music.

Harmony can be fully scripted by a composer, or it can be outlined by a composer and fully expressed by the players performing the music. The orchestral scenario described above is an example of harmony that’s tightly scripted by a composer—he or she has assigned specific notes many single-note instruments, and those notes combine to form chords. This is common practice in the European tradition of classical music.

Another common way for composers to express harmony is to declare a particular chord progression and then allow players to craft their own parts to fit that progression.

In the song “Down on the Corner” by Creedence Clearwater Revival:

• The song is written in the key of C major.
• It uses a common progression of chords for that particular key, mostly fluctuating between a C major triad and a G major triad, with F major triads thrown in at key points.
• As such, instrumentalists are expected to use the C major scale to write parts that fit the chord progression.

During the song’s intro section, Stu Cook lays down a bass line that’s mostly single notes, rhythm guitarist Tom Fogerty punches out 5-note and 6-note chords, and lead guitarist John Fogerty plucks a melody based on the C major scale. They are accompanied on drums by Doug Clifford. Everyone is playing in harmony, following both the chord progression and the overall key of C major.

Sometimes, players don’t play all the notes in a chord: they use “implied harmony” to let the listener’s ear fill in what is missing. This is a particularly popular technique in jazz.

For instance, let’s consider the dominant 7th chord, one of the building blocks of jazz music.

• Dominant chords consist of 4 pitches: the root, the major 3rd, the 5th, and the dominant 7th.
• To cite a real example, a G7 chord consists of G (the root), B (the major 3rd), D (the 5th), and F (the dominant 7th).

Now, let’s say a jazz ensemble has two saxophones, each of which can only play one note at a time.

• The goal is to play a G7 chord, but due to instrument limitations, we only have two notes that can be sounded at the same time.
• While a rock player might choose the root and the 5th for the most powerful sound, the jazz players will almost surely choose the 3rd and the 7th, because those are the notes that establish the character of the dominant 7th. So to imply a G7 chord, they would play the B and the F.
• It’s strange that neither of these instruments would play a G to imply a G chord, but as most jazz saxophonists would tell you, that’s what bassists are for.

Indeed, bassists also imply harmonies because they, too, typically only play one note at a time. For instance, a bassist might play the note F, which is supposed to be the root of a chord. But is it an F major? F minor? F diminished? The theory of tonal harmony (and a listener’s innate understanding of it) will help establish what the full chord is supposed to be.

• If we’re in the key of D minor, then it’s almost certainly an F major chord. F major is the bIII chord in the key of D minor and its notes (F-A-C) are all part of the D minor scale.
• If we’re in the key of Eb minor, then it’s almost certainly an F diminished chord, because F diminished is associated with the Eb minor scale.

Harmony takes many forms. Here are the three most popular and important forms of harmony.

• Diatonic harmony. This is music where the notes and chords all trace back to a master scale. So if you’re in the key of Ab major, all the notes and chords you play will be drawn from the seven notes comprising the Ab major scale. And if you’re not sure what key you’re in, check the “key signature”—the list of sharps and flats that appears at the beginning of each system of musical notation. Diatonic harmony can be found in everything from ancient Greek instrumentals to Renaissance chorales to contemporary pop hits.
• Non-diatonic harmony. Non-diatonic harmony introduces notes that aren’t all part of the same master scale. This form of harmony is completely idiomatic to jazz, but it appears in all forms of music. Let’s say you’re in the key of Ab major and you play a Bb7 chord. That chord contains the note D, which is definitely not in the Ab major scale. It sounds a bit edgy, but it also tends to be quite memorable. “Somebody to Love” by Queen is a good example of this. When Freddie Mercury sings “I’ve just gotta get out of this prison cell” the word “out” falls on a Bb chord in the key of Ab. But non-diatonic harmony is not a new concept. The preludes and fugues of Johann Sebastian Bach are roughly 400 years old, but they remain a master tutorial in the melding of non-diatonic notes with traditional key signatures.
• Atonal harmony. This form of harmony doesn’t have a tonal center: it isn’t built on a scale that’s major or minor, or that has an identifiable root. In classical music, atonal music was largely the brainchild of composer Arnold Schoenberg. Schoenberg personally disliked the term “atonal” and described his technique as “twelve-tone music” where all twelve of the pitches used in Western music were equal in the harmonic language. Atonal harmony also became popular in the free jazz movement spurred by players like Ornette Coleman and Don Cherry.

All music with pitches contains harmony, whether manifested in a huge orchestra or implied by a single instrument. Together with melody and rhythm, harmony is fundamental to the music humans have enjoyed for millennia.