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A few snatches of interesting comments:
Also, like the great English choirs and many early-music groups, I insist that CAC singers be able to completely turn off their vibrato if a particular piece or passage calls for it. This technique enhances the tuning of every chord. Readers familiar with Renaissance music will know the term “just intonation,” which is what we mostly strive for in our singing – to line up the harmonies with the overtone series created by the singing of pure intervals, which is a totally different harmonic “groove” from what you’ll get on a tempered keyboard.
A suggestion from a workshop:
Rogers is one of my heroes. I’ll never forget taking a masterclass from him in 1988, when he just suggested the slightest upward pull in pitch on all the rising lines that my pickup student group was singing… and all of a sudden, we sounded like one of those hot English choirs!