Acoustic dimensions of hearing-impaired speakers' intelligibility

Regression and principal components analyses were employed to study the relationship between three measures of speech intelligibility and 12 segmental, prosodic, and hearing ability parameters in 20 severely to profoundly hearing-impaired speakers. Regression analyses on the original 12 parameters revealed that cognate pair voice onset time differences and mean sentence duration strongly predicted speech intelligibility based on readings of isolated word and contextual speech material. A principal components analysis derived four factors that accounted for the majority of the variance in the original 12 parameters. Subsequent regression analyses using the four factors as predictor variables revealed two factors with strong relationships to the speech intelligibility measures. One factor primarily reflected segmental production processes related to the temporal and spatial differentiation of phonemes, whereas the other factor reflected prosodic features and production stability. These results are consistent with prior research that suggests independent primary and secondary roles for segmental and prosodic speech characteristics, respectively, in determining intelligibility in severely to profoundly hearing-impaired speakers.