Intelligibility of Different Speech Materials

Articulation scores for nonsense syllables and for monosyllabic, disyllabic, and polysyllabic words were obtained as a function of the cut-off frequency of low-pass and high-pass filters and also as a function of signal-to-noise ratio at different noise levels. Results indicate that eliminating all frequencies above or below 1600 cps does not impair the intelligibility of words seriously. The intelligibility of a word is a direct function of the number of syllables in the word and monosyllabic words are more intelligible than nonsense syllables. The relation between the intelligibilities of each word type and nonsense syllables is not the same when the system is impaired by filtering as it is when the system is impaired by noise. The implications of the lack of consistency from one experiment to the other for the generality of the concept of articulation index is discussed.