SOUND PATTERNS

4.1 TRIADS

SONORITY is a generic term for a collection of pitches that may be sounded simultaneously; it can be interchangeable with words such as "chord" or "harmony". The basic sonority of the Common Practice Period is the TERTIAN TRIAD. A triad is a collection of three different pitches, and tertian indicates that these pitches are stacked in intervals of 3rds (either major or minor).

There are only four possible combinations with these two intervals:

• M3 + m3
• m3 + M3
• m3 + m3
• M3 + M3

• The first one, a M3 on the bottom and a m3 on top, is called a MAJOR TRIAD (M).
• The second one, a m3 on the bottom and a M3 on top, is called a MINOR TRIAD (m).
• The third one, two m3's outlining a d5, is called a DIMINISHED TRIAD (d)
• The fourth one, two M3's, outlining an A5, is called an AUGMENTED TRIAD (A).

Calculating triads is a matter of stacking pitches into 3rds and identifying the intervals. Begin by learning all the basic triads (natural notes) first.

Learn more about triads

4.2 TETRADS

It is possible to stack one more 3rd on top of a triad, creating a TERTIAN TETRAD (four notes stacked in 3rds). These are also known as SEVENTH CHORDS, named for the interval from the bottom pitch to the top one.

All tertian tetrads have two names: one for the triad on the bottom (major, minor, diminished, or augmented) and a second for the type of 7th (M7, m7, or d7). The basic tetrads:

Some chromatic examples:

4.3 CHORD FACTORS

Each part of a triad has a specific name: when stacked in 3rds, the ROOT is the bottom note, the CHORDAL THIRD is in the middle, and the CHORDAL FIFTH is the top. These names are the same for tetrads, with the CHORDAL SEVENTH being the extra note.

4.4 POSITIONS OF SONORITIES

Any chord factor may occur in the bass voice, creating different POSITIONS for these sonorities. Positions of triads and tetrads are determined by the bass only; the placement of chord factors in the upper voices are irrelevant to defining position.

• Root in bass: ROOT POSITION
• Chordal third in bass: FIRST INVERSION
• Chordal fifth in bass: SECOND INVERSION
• Chordal seventh in bass: THIRD INVERSION

Positions of triads represent various degrees of stability, and are like positions of cones.

• Root position is the most stable form aurally, like a cone sitting on its base.
• The first inversion is less stable aurally, like a cone lying on its side; the cone maintains its relative position, but is not fixed in one place.
• The second inversion is the least stable aurally, like a cone on its point; the cone cannot maintain its position.

Root position	1st inversion	2nd inversion
Root in the bass: most stable position	Chordal third in the bass: less stable position	Chordal fifth in the bass: least stable position

Learn more about positions of triads

DRILLS

Continue to drill past material at Ricci Adams' music theory.net.

Sonority Drills