**Abstract:**

STI (including the abbreviated version, RASTI), %Alcons and the 50-ms early-to-late sound energy ratio (C[inf 50]) are well known as predictors of speech intelligibility. Among these, C[inf 50] is the least used both as a design equation and for room-acoustic and sound-system measurements, and its performance as a predictor of intelligibility is probably the least well validated. To better understand the performance of C[inf 50], data from miscellaneous sources are examined with respect to: (1) correlations between the predictors; and (2) their ability to predict actual intelligibility from measurements and from calculations using statistical-behavior formulas. Relationships are shown between calculated values, between calculated and measured values, and between measured values for the three predictors.

ASA 133rd meeting - Penn State, June 1997