Speech Intelligibility in the Presence of Time-Varying Aircraft Noise

There has been some question as to whether the relationship between the articulation index (AI) and intelligibility test scores established for steady-state noise can be used to predict intelligibility scores that would be obtained in the presence of time-varying aircraft noise. For various aircraft flyovers, speech intelligibility scores and various noise measurements 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 AI and speech intelligibility for flyover noise was different from the relation obtained for the steady-state noise. The various noise measures were almost equally effective in predicting speech intelligibility in the presence of flyover noise. There is an appreciable disruption of contextual speech when the peak level of a flyover exceeds 88 PNdB, an SIL of 68 dB, and an A-weighted sound-pressure level of 76 dB. [Work supported by Federal Aviation Administration.]