Chordal accompaniment (aka pad)
When writing sustained chordal backings for a solo instrument or unison line, you can use instruments of the same or different section playing sustained chords. The lead line of the chordal accompaniment should move smoothly paying attention to voice leading where possible. This lead line can be harmonised with close or open block voicing, or traditional choral type voicing. The melody should obviously predominate over the backings. This is often done by writing it higher in pitch, but this is not absolutely necessary, especially if the melody is on a stronger instrument. You can swap between block voicing and chordal accompaniment freely within the same passage.
You should take care with range and dynamics to avoid swamping the melody with the backings, especially if the accompanying instruments are of the same section as the solo instrument. With a different section you also need to take tonal dynamic considerations into account, especially when the accompanying instruments are stronger, e.g. great care would have to be taken if a flute were taking the melody and brass instruments were sustaining a chordal backing. This kind of “imbalance” can work in a studio with close miking but not in an acoustic situation. In this case it would be good to use mutes on the trumpets.
Stabs or short rhythmic phrases
These nearly always fill the gaps
in and around the melody, usually with a different section of instruments (a common big band or jazz orchestra cliché). It was often necessary on vocal arrangements in the days before powerful PA systems when a sustained backing would often drown out a singer in a club. Obviously great care should be taken if the stabs or backing figures are not in the gaps of the tune, as they may confuse the melody. It can be very effective if the stab phrases have some kind of unity, e.g. repeated riffs. The riff may have to adapt to the harmonic changes (especially good if they move logically in scale steps). This often gives a feeling of shape that may not happen if the phrases are more arbitrary. Either way the phrases should complement the melody.
Counterpoint
This is where a second (subordinate) melody is played at the same time as the main melody. This can be a completely independent melody or an imitation (fugue).
Some good rules to observe are:
- The counterpoint should sustain while the melody is moving and vice versa
- Contrary motion works very well
- If the melody is in unison or octaves it can be a good idea to have the counterpoint in (block) harmony and vice versa.
- The parts can cross, but preferably if the counterpoint is played on a different timbre instrument or section.
