Choral voicing is a technique with long-standing history used by choral directors to seat singers based on characteristics of the voice - color, tone, timbre, placement, and vibrato. Contrary to popular belief, this technique is not just for college and professional choirs. Try it at home with your church choir, community choir, and even children's choirs! It will be well worth your time.
Each voice has a unique series of overtones, which contributes to timbre (source). The ideal choral sound is based on overtone series that complement each other rather than clashing. Having singers with like, complementary voices stand next to each other creates a natural "blend" that does not require singers to compromise their vocal technique. Did I mention it fosters the best intonation? It's a win-win, really.
Here are some of the best-kept secrets of choral voicing: