Intervals: The difference between two pitches. The closest interval is a union, where two notes of the same pitch are sounded. Regarding consonance, the most harmonious-sounding interval is the eighth (the octave), the second, the fifth, and the third, the fourth. The third and the sixth are also considered consonant. Generally the second and the seventh are dissonant.
Melodic motion: The spacing of notes in a melody (tune). Most melodies consist of movements between notes in steps (a spacing that’s one full note from the other), half-steps, leaps and repeated notes. Sometimes, in melodies where the melodic motion is primarily shaped by simple steps and half-steps, a sudden leap at a place or two will provide melodic interest.
Melodic sequence occurs when a melodic pattern is repeated at a different pitch level.
Contrast and return is an effective melodic device that is often used in music – in a piece, it means the melody is structured in an A-B-A form, with the middle part being the contrast and the second A the return. Somehow it sounds rather ‘musically satisfying’ and is often used when composers structure their music. A rather interesting variation is the A-B-A’ form, where the return is slightly varied.
Harmony: how accompaniment in music is structured (but I don’t like this definition). The most common consonant chord is the triad, where the 1st, 3rd and 5th notes of a scale are played. The first note is the root, sometimes the accompanying notes may not be above the root in pitch, but the root (whether placed at the bottom, middle or top) still remains one, as it is the note on which the triad was originally based. Variations of the triad exist, one of them being the seventh chord, where a flattened seventh is added to the triad. The effect produced is a slightly dissonant chord that signals subsequent movement to a different triad.
A keynote is the note on which a piece is based on. If a piece is based on the keynote C, the piece is said to be written in the key of C.
When one arranges the notes belonging to a keynote in order, a scale is created. Scales give musical colour to a piece. Divided into two categories, the major and the minor.
A major scale’s sequence is: 1-1-1/2-1-1-1-1/2
where 1 denotes a whole step and 1/2 a half-step. Using any keynote one can form a major scale by this sequence.
A minor scale’s sequence is: 1-1/2-1-1-1/2-1-1
Notes from a major scale tend to have a more brightened and cheerful effect, the minor scale more serious, to some extent, depressive.
There are variations within the minor scale, the aforesaid is the natural minor, a harmonic minor: 1-1/2-1-1-1/2-1/2-1 exists that is normally used when harmonising a minor key. A melodic minor is used when composers write a minor melody, and sounds slightly different in ascending and descending order.
Other scales are sometimes used, such as the pentatonic and the chromatic (moves almost entirely by half-steps).