Standard 5: Triads

Our objectives:

  • Identify all triads, including: major, minor, augmented, diminished.
  • Identify the root and quality of a triad using a lead sheet symbol.
  • Complete a triad with a given quality and root.

5.1 Chords and Triads

Now that we are familiar with the basic building blocks of melodic writing, let's take a look at harmony. First, a few definitions:

  • A chord is any combination of three or more pitches that sound simultaneously.

  • A triad is a three-note chord whose pitches can be arranged in a series of thirds.

To quickly determine whether a three-note chord is a triad, arrange the three notes on the "circle of thirds" below. The pitch classes of a triad will always sit next to each other.

A triad (A, C, E) on the diatonic circle of thirds.

5.2 Identifying and labeling triads

Triads are identified according to their root and quality.

5.21 Triad roots

To find a triad’s root, arrange the pitch classes on a circle of thirds (mentally or on paper). The root is the lowest in the three-pitch clump. Expressed another way, if the circle ascends by thirds as it moves clockwise, the root is the “earliest” note (thinking like a literal clock), and the other pitch classes come “later.”

A triad (A, C, E) on the diatonic circle of thirds.

Once you know the root, you can identify the remaining notes as the third of the chord (a third above the root) and the fifth of the chord (a fifth above the root).

5.22 Triad qualities

To find a triad’s quality, identify the interval between the root and the other members of the chord. There are four qualities of triads that appear in major and minor scales, each with their own characteristic intervals.

  • major triad: Major 3rd and Perfect 5th above the root (as in do–mi–sol)
  • minor triad: Minor 3rd and Perfect 5th above the root (as in do–me–sol or la–do–mi)
  • diminished triad: Minor 3rd and Diminished 5th above the root (as in ti–re–fa)
  • augmented triad: Major 3rd and Augmented 5th above the root (as in me–sol–ti)

Four qualities of triads.

Take a listen below (press "play" on the upper-left hand corner) to the four different qualities:

5.3 Lead Sheet symbols

A triad can be summed up by a single symbol, such as a lead sheet chord symbol. A lead sheet symbol includes information about both root quality, as well as which pitch class occurs in the lowest voice (called the bass regardless of who is singing or playing that pitch).

A lead sheet symbol begins with a capital letter (and, if necessary, an accidental) denoting the root of the chord. That letter is followed by information about a chord’s quality:

  • major triad: no quality symbol is added
  • minor triad: lower-case “m”
  • diminished triad: lower-case “dim” or a degree sign “°”
  • augmented triad: lower-case “aug” or a plus sign “+”

Finally, if a pitch other than the chord root is the lowest note in the chord, a slash is added, followed by a capital letter denoting the pitch class in the bass (lowest) voice.

A C-major triad’s lead sheet symbol is simply C. A C-minor triad is Cm. A D-sharp-diminished triad with an F-sharp in the bass is D#dim/F#. And so on.

Four qualities of triads with lead sheet symbols.

5.4 Building a triad

To build a triad on the staff, identify the root, quality, and bass note for the triad. The root and quality will tell you what three pitches belong to the triad. For example, C+ tells you the root is C, and the quality is augmented. Since the quality is augmented, there is a major third above the root (E) and an augmented fifth above the root (G-sharp).

Next, write a C on the staff (in any comfortable register), then write the other chord tones (E and G-sharp) above the C (see the Caug triad in the above figure).

5.5 Listening to triads

Each triad quality has its own distinct sound, and to an extent that sound is preserved even when the chord is inverted (when the pitches are arranged so that a pitch other than the root is in the lowest voice). As you practice identifying and writing triads, be sure to play the triads, both to check your analysis/writing and to develop the ability to identify chord qualities quickly by ear.