Speech intelligibility in cars: the effect of speaking style, noise and listener age

Intelligibility of speech in noise becomes lower as the listeners age increases, even when no apparent hearing impairment is present. The losses are, however, different depending on the nature of the noise and the characteristics of the voice. In this paper we investigate the effect that age, noise type and speaking style have on the intelligibility of speech reproduced by car loudspeakers. Using a binaural mannequin we recorded a variety of voices and speaking styles played from the audio system of a car while driving in different conditions. We used this material to create a listening test where participants were asked to transcribe what they could hear and recruited groups of young and older adults to take part in it. We found that intelligibility scores of older participants were lower for the competing speaker and background music conditions. Results also indicate that clear and Lombard speech was more intelligible than plain speech for both age groups. A mixed effect model revealed that the largest effect was the noise condition, followed by sentence type, speaking style, voice, age group and pure tone average.