Melodic motion

There are two ways for notes to behave in a melody.

• Step: the next note in a melody is one scale degree (difference of one letter name) or the interval of a (2) second away.
• Skip (leap): next note is not a step away

Contrapuntal motion

A voice in music refers to an independent line of melody. In actual music voices can be doubled (played by multiple instruments) or harmonized (played with multiple pitch levels), but this does not mean additional voices have been created. A line of music must be sufficiently unique in its contour (pitches) or rhythm to be noticeable as a separate voice. Counterpoint is the technique of writing multiple voices that are distinct from one another.

Here is a list of ways that two voices can move relative to one another from most alike (least contrapuntal) to least alike (most contrapuntal).

• Parallel motion: both voices move in the same direction and distance (creating parallel intervals)
• Direct motion (similar motion): both voices move in the same direction (creating hidden parallels)
• Oblique motion: only one voice moves, the other stays stationary
• Contrary motion: the voices move in opposite directions (inward or outward)

Consonance and Dissonance

Here are commonly found intervals listed from most consonant to most dissonant. To compare compound intervals (intervals greater than an octave), first reduce to simple intervals.

• Consonant
  • Perfect
    • (1/8) perfect unison and octave
    • (5) perfect fifth
    • (4) perfect fourth (sometimes)
  • Imperfect
    • (3/6) major and minor third and sixth
• Dissonant
  • (4) perfect fourth (sometimes)
  • (2/7) major and minor second and seventh
  • (x4/°5) augmented fourth or diminished fifth, plus all other augmented or diminished intervals

An interesting note: composer Paul Hindemith further divided dissonances into perfect and imperfect dissonances. According to him, dissonant intervals that occur naturally in a piece of music’s scale or mode are perfect, while intervals that have been modified (augmented/diminished) are considered imperfect. Hindemith describes this theory in his book The Craft of Musical Composition.

While the (P4) perfect fourth is objectively consonant, it has a subjective reason for being a dissonance. In the Renaissance and Baroque eras it was treated as dissonant because harmonies resolved to triads, which do not contain strong intervals of a fourth. In later periods fourths were used more often as consonants. Hindemith also suggests an objective explanation for a dissonant fourth: the combination tones (another property of overtones) of a perfect fourth produce a pitch that reinforces the upper note instead of the bass, whereas the combination tones of a perfect fifth reinforce the lower note. This makes the fourth sound less stable, as it wants to be heard in terms of the upper note.