The harp, guitar, and piano all have the capacity to perform chords, or simultaneous combinations of pitches. They are often selected by the orchestrator to provide a harmonic and rhythmic accompaniment to solo winds, strings, and voices. They can also be used to support their own melodies, providing both the primary line and background figures. A wide range of accompanimental techniques can be employed with these chordal instruments. In homophonic music with a single line melody and a chordal background, patterns can be devised that provide a harmonic context for the melody and also establish the degree of rhythmic activity. Common figures for the chordal instrument in this capacity are created in some of the following ways:
1. Arpeggiate the chords upwards or downwards, where the lowest note becomes the bass, and the figure remains constant in its shape. The alberti bass is an example of this type of figure.
2. Alternate single bass notes with block chords. This common figure is used in the waltz and in marching band music. Syncopating the rhythm between the bass and chords creates a ragtime effect.
3. A tremolo figure alternating between two different pitches is a useful device that provides some density. The two pitches must be chosen carefully to elucidate the harmonic content most clearly.
4. A combination of arpeggiated and tremolo figures can be used. A particularly effective device is imitating fragments of the melodic line in the accompanimental part, which integrates the two functions and creates new expectations for the listener.
5. Repeating block chords in a regular pulse or rhythmic pattern is a good way to heighten the forward progress to points of arrival and lend power to the overall texture.
6. Long sustained chords, quietly rolled or arpeggiated, can provide a serene background to prepare the entry of a solo instrument.
There are many other possibilities, and the best accompaniments use a combination of figures and devices to enhance the musical flow. The character of the music and the ranges of the instruments used are both critical factors in determining the most suitable choices. In general, it is better to understate the accompaniment than to build an overly active texture that competes with primary melodic material.
For practice in creating supporting textures with a chordal instrument, select a melody and harmonize it with an original accompaniment for harp, guitar, or piano. Perform your arrangement with a solo voice or instrument and the accompaniment.