The relative effects of three expressive methods upon the speech intelligibility of profoundly deaf speakers

Two studies, conducted over a nine month interval, were designed to evaluate the relative effects of three expressive methods (speech alone, speech and signs, and speech with cues) upon speech intelligibility. Five profoundly deaf adults, who were receiving continuous speech training, were recorded reading lists of individual words under all three expressive modes. Listeners were required to identify through a multiple choice format the target stimuli from auditory presentations only. Study I results indicated that speech with cues produced the highest level of intelligibility, while speech and signs produced the lowest level. Study II, with an expanded set of word stimuli, found that speech alone produced a 65% rate of correct identification by listeners; speech and signs again produced the lowest rate of correct identifications. Implications for the assessment and understanding of speech intelligibility are considered.