Talker intelligibility and listening effort: the role of speaking rate

Listening to speech in noise induces increased cognitive effort and fatigue. Effort is mediated by listener characteristics such as nativeness or hearing status. Moreover, noise-related issues can be exacerbated by talker differences. Nevertheless, past research has so far not related talker differences to cognitive effort. Based on an anechoically recorded corpus of sentences spoken by sixteen Southern British English speakers, we conducted listening experiments in combination with pupillometry. We presented temporally or spectrally distorted speech (using time-compression and noise-vocoding, respectively). Furthermore, undistorted speech was presented in quiet and embedded in speech-shaped masking noise. Intelligibility measures were obtained based on keywords recalled correctly. Listening effort was measured by tracking pupil size over time. Our results show that peak pupil dilation increased for both distorted and masked speech. Peak pupil dilation also increased for less intelligible talkers in the temporally degraded condition. The results indicate a link between speaking rate differences and listening effort and will be discussed in the context of models of listening effort.