For choral music, our members sing without any audible vibrato, they blend smoothly with each other, and they are excellent sight-readers. We base our intonation on the harmonic series pure interval of the perfect fifth (the way stringed instruments tune). This means we avoid the equal temperament of the piano, which slightly diminishes every "perfect" fifth. By keeping fifths truly perfect, our system creates harmonies and melodies with slightly wider major intervals and narrower minor ones than many singers are used to producing. The sound, we believe, is the most beautiful realization of polyphonic music composed in the Renaissance, and in many other periods as well.