Abstract
On condition that speech is disturbed by echo and noises, the possibility of predicting syllable intelligibility on the distributed public address system in an open-air stadium has been investigated, using proposed predicting method which assumes the value of syllable articulation in a real field would be the same as what would be calculated were the disturbing echo energy replaced by equivalent noise. The stadium is 210 by 173 meters in size, 29 000 square meters in the total area, can accommodate 20 639 people in the stand, and for public address system 48 reflex-horn type loudspeakers are distributed around the stand. Acoustics and three CV syllable intelligibility in Japanese were measured, and articulation index was calculated by the predicting method using physical data measured in the stadium. Three combinations of the following calculated syllable articulations in echoes were considered : Svv of vowel is interfered by echo vowels ;Scv of consonant is interfered by echo vowels ; Scc of consonant is interfered by echo consonants. As a case of the first application to real field, there were high correlation between the results measured in the stadium and calculated by the predicting method, 0.7477 of the coefficient of correlation was obtained by multiple regression analysys.
