Singing Four Parts with Mid-level Students

The question is:  Which voicing is best for choirs containing early adolescent voices -- unison, two, three, or four parts?   The number of boys enrolled in the choir provides the answer.  If there are numerous girls and only two boys, it is very difficult to perform four-part music.  On the other hand, if there are numerous girls and at least four boys, directors may be surprised at how successfully the choir can sing four parts.  Some directors are inclined to place all the boys (if there are as few as four) on one part and divide the girls into two groups (Soprano I and II), thinking that four boys can balance ten girls on each part better than two boys.  If all four boys are cambiatas or if they are all baritones, that is sound logic; but if there are at least two cambiatas and two baritones, consider this reasoning.  Contemplate the comfortable singing tessitura of both cambiatas (from A below middle C to A above middle C) and baritones (D, middle line in the bass clef up to D above middle C).  If they sing together comfortably, they must sing a part that has an overall compass of A (top line, bass clef) upward to D (above middle C), only an interval of a fourth. Directors may choose a part that is written with an overall compass of F (fourth line, bass clef) to F (above middle C), which represents a composite overall range capability of both voices, a full octave which is the range found in more SABoys music.  In either case, there are problems when the boys sing the part together.  The part will keep the baritones in the upper area of their voices all the time, which causes vocal tension, poor intonation, and unhealthy vocal results.  The same part will keep the cambiatas in the lower area of their voices all the time, which does not allow them to use the most comfortable and best-sounding tones of their vocal instruments, the tones of D (above middle C) upward to G.  Therefore, none of the boys will be able to sing in the best area of his voice.  Putting them together hampers both cambiatas and baritones.  If the two cambiatas and two baritones are allowed to sing two separate parts written specifically for them, parts that permit the boys to use the most comfortable singing area and best tones of each, two boys are more likely to balance ten girls than are four boys who are hampered by the part they must sing.  For that reason, early-adolescent choirs almost always will function better singing four parts rather than three or less, provided those four parts are written to accommodate their vocal limitations.