4Projection of SoundA good auditorium will accomplish effective projection of the sound to the rear of the auditorium so that those distant listeners will not experience the extreme loss of sound level caused by the inverse square law. That projection is normally achieved by having a sufficiently long reverberation time. Another significant contributer will be a high, reflective ceiling to reflect sound to the back of the auditorium.
5Even DispersionSound is more pleasing if it is evenly dispersed, with no prominent echoes, no significant "dead spots" or "live spots" in the auditorium. This even dispersion is usually achieved by avoiding any focusing surfaces and avoiding large flat areas which reflect sound into the listing area. Sometimes it is desirable to add some anti-focusing surfaces.
6After all the main characteristics of auditorium acoustics are accounted for: proper reverberation time, longer reverberation time for low frequencies, even dispersion, etc., there still remain nuances which cause persons to prefer some apparently comparable auditoriums over others.