Computer model studies to predict qualitative and quantitative measures of speech intelligibility in class rooms

Abstract

Computer model studies were used to predict qualitative and quantitative measures of speech intelligibility in classrooms under realistic conditions of background noise and reverberation. Fifteen different acoustical measurements related to speech intelligibility were made at multiple locations in three actual classrooms and in computer models of the classrooms. Speech intelligibility (MRT) tests were given to human subjects in each of the actual classrooms at five signal-to-noise ratios. Speech intelligibility tests were also prepared from aural simulations obtained by convolving anechoic speech tracts with impulse responses obtained in the computer models. Correlations (R2) between acoustical measures made in the full size classrooms and the computer models of the classrooms of 0.92 to 0.99 with standard errors of 0.033 to 7.311 were found. The scores on the speech intelligibility tests given in the actual rooms in the five noise conditions were closely duplicated in the equivalent tests conducted in a sound booth using the simulated speech signals obtained in the computer models. Both quantitative and qualitative measures of speech intelligibility in the actual rooms were accurately predicted in the computer models.