The Wall of Sound
A problem I face in rehearsal is that of muddy ensemble sound. This is most commonly noticed in homophonic passages, where the chords don't ring as clearly as I want. Poor synchronization of word sounds is often the culprit. I use this process (borrowed from barbershoppers) to clean up the vocal lines. It’s called THE WALL OF SOUND, because it creates a strong, uninterrupted sound from the choir. Vowels are bricks and consonants the mortar. In a strong wall there must be much more brick than mortar; the mortar must completely connect the bricks.
Step 1 - Model in unison: Sing the passage on one mid-range note that is accessible to the choir (in octaves for mixed choirs). Sing it as you wish to hear it. Have the choir then sing it back to you on that unison note. Listen carefully for the treatments of consonants and vowels, including diphthong turns. Make sure the choir is following your timing in all ways, and that the pitch doesn't bend or scoop at all. Make them tunnel forward with a constant stream of sound. The goal is to become one voice. If needed, slow the tempo down to hear the timing of word sounds, then gradually speed up until you hit performance tempo.
Step 2 - Spread to a chord: After the word sounds are synchronized across the choir in unison, assign each section a note in a chord in the key of that section. Example: F Major-basses/F, tenors/middle C, Altos/F, sopranos/A. Sing the passage on this static chord, working synchronization as you did in the unison. The goal is to create a constant, ringing sound where vowels are matched, singable consonants ring with true pitch, and plosives click together. Again, vary the tempo as needed to make sure everyone is moving together cleanly. If this is too ambitious, start with the cleanest section, then add others one at a time for quality control.
Step 3 - Resume parts: Have sections sing their original notes but in the new style of the static chord. The goal is to now hear THE WALL OF SOUND. Variation of tempo is valuable in this stage, to ensure everyone’s word sounds are synchronized.
There are other considerations to maximize chords in THE WALL OF SOUND, but that's another bite.