Loudspeaker, narrator and language influences on speech intelligibility

Results obtained during a very limited budget experiment obtaining speech intelligibility levels with word lists in English and Afrikaans and a panel of listeners. A variety of selected loudspeakers were used, with electrical gain set at ten decibels below the onset of acoustical feedback for each loudspeaker, using the same microphone in each case, in a sound reinforcement configuration in the presence of equalised random noise. Good correlations were obtained between some tests using the same recorded word lists in the same listening locations with the same loudspeakers. Different speech intelligibility score profiles were obtained, however, for different word lists, in which the differences were attributed to the narrators and language only. Attempts were made to explain the differences, by investigating the data. Poor correlation was found between actual speech intelligibility scores and theoretical predictions using the Articulation Index.