Evaluating the articulation index for auditory–visual consonant recognition

Adequacy of the ANSI standard for calculating the articulation index (AI) [ANSI S3.5‐1969 (R1986)] was evaluated by measuring auditory (A), visual (V), and auditory–visual (AV) consonant recognition under a variety of bandpass‐filtered speech conditions. Contrary to ANSI predictions, filter conditions having the same auditory AI did not necessarily result in the same auditory–visual AI. Low‐frequency bands of speech tended to provide more benefit to AV consonant recognition than high‐frequency bands. Analyses of the auditory error patterns produced by the different filter conditions showed a strong negative correlation between the degree of A and V redundancy and the amount of benefit obtained when A and V cues were combined. These data indicate that the ANSI auditory–visual AI procedure is inadequate for predicting AV consonant recognition performance under conditions of severe spectral shaping.