Harmonic Concepts and Part Writing

VOCAL RANGES

Voices have different qualities in the low, middle, and upper parts of their rangeSingers are most comfortable in the center part of their range, where they have flexibility for changes in color.  The upper part of the vocal range is significantly louder and brighter, while the lower range is softer and darker.  Professional singers are able to work in the extremes of their range, but it should be used sparingly, for special effects.  Young or inexperienced singers will have limitations at either end of their range.  The follow chart shows conservative ranges for an average choir.

WRITING PARTS FOR FOUR VOICES

It is often the arranger’s job to harmonize or reharmonize a melody.  There are several common conventions that can be followed which yield an arrangement that is stylistically consistent with common-practice norms.  Here are a few conventions for harmonizing melodies:

  • Chords usually progress Down a 5th, Up a 2nd, or Down a 3rd in tonal music.
    Retrogressions in which any chord may move to the Tonic or Dominant are common
    Chords move from Subdominant (ii or IV), to Dominant (V or vii), to Tonic (I or vi)
    Scale degrees 2 and 7 are usually harmonized with the Dominant function
    Scale degrees 4 and 6 are usually harmonized with the Subdominant function
    Scale degrees 1 and 5 may harmonized with the Tonic or another function
    Scale degree 3 is usually harmonized with the Tonic function

The most stable voicing for a chord is with the root in the bass voice.  There are certainly times when we need to give stepwise motion to the bass part, but at points of arrival and cadences roots are best.  For smooth linear movement in each part, review the Guidelines for Voice-Leading in the accompanying materials.  Adhering to these principles will yield a very singable result, and facilitate sight-reading of a score.  Singers can easily find their pitches voiced in a simple, diatonic triad.  Moving to highly chromatic chords is also easily accomplished if the motion is by half-step in each voice, with common tones between chords held in the same voice.  Leaping to chromatically altered pitches is most difficult, and may lead to extended rehearsal time and intonation problems. 

Composers choose a key for good reasons.  However, it is wise to consider whether transposing might yield a better result for your choir if the original key is not within vocal ranges.  If you want a low bass note under the ensemble, choose a key that allows most basses to hit that low note.  Typically, the upper voice is heard as the melody, so the Soprano part usually is assigned to the melody.  If the other voices are kept in the background, singing mono-syllables or humming, any voice could present the melody.  As far as doubling the melody, any of the other parts might double the Sopranos at the octave.

GENERAL CONSIDERATIONS

One of the top priorities in scoring choral music is to be sure the listener can understand the lyrics.  Although it may be effective to have several parts singing different words at the same time, clarity of the text should govern the use of this technique.  Part of a phrase is often repeated to elongate the lines, or to give emphasis.  This is a chance for different vocal sections to interact in an imitative fashion.  It is important to think about the role of each voice in the texture, and to vary the density as the music evolves.