Speech intelligibility in the presence of time-varying aircraft noise

This study concerns the question of whether or not the relation between intelligibility test scores and the Articulation Index (AI) established for steady-state noise can be used to predict speech intelligibility in the presence of time-varying aircraft noise. For various aircraft flyovers, intelligibility scores and several noise measures were obtained as functions of time. In addition, intelligibility scores and measures of AI were obtained for steady-state simulated aircraft noise. The relation between speech intelligibility and AI for time-varying noise was different from the relation obtained for steady-state noise. The various noise measures were almost equally effective in predicting speech intelligibility in the presence of time-varying aircraft noise. There is an appreciable disruption of contextual speech when the peak level of a flyover exceeds 88 PNdB, a speech-interference level of 68 dB, or an A-weighted sound-pressure level of 76 dB.