The acoustic quality of a concert hall has frequently posed a mysterious puzzle, namely, what physical aspects of the sound field can produce superior sound for the listener. The author has been probing for more than adecade into the subjective qualities preferred for musical and speech sounds. The result of his extensive investigations - the discovery that four and only four independent parameters contribute effectively to good acoustics - is summarized in the present book. The capability of calculating acoustical quality at any seat in a proposed concert hall is a unique and quite useful aspect of Ando's design method. Alternative architectural schemes can be compared based on the number of seats which exceeds a previously accepted minimum standard of acoustical quality.