Comparative Intelligibility of Word Lists and Continuous Discourse

Intelligibility scores on Harvard Phonetically Balanced (PB-50) Word Lists, Central Institute for the Deaf (W-22) Monosyllabic Word Lists, and a sample of continuous discourse were compared. Speech samples were recorded on magnetic tape under seven high frequency filtering conditions. One-hundred and seventy-five normally hearing subjects were divided into seven groups, each group listening to all speech samples under one particular condition of filtering. Word lists were scored in terms of number of words correct and the continuous discourse in terms of items correct on a test covering information presented in the continuous discourse. The following results were obtained: (1) Consistently higher scores were achieved with the W-22 word lists than with the PB-50 word lists, even when the influence of dissimilar recordings was eliminated. Such differences were attributed to a combination of differences in list content and recording conditions. (2) Monosyllabic word lists and continuous discourse are affected in the same way by frequency distortion; that is, errors increase as distortion increases. (3) No accurate intelligibility score prediction for the continuous discourse could be made on the basis of scores obtained on the PB-50 and W-22 lists.