Effortful listening under the microscrope: Examining relationships between the task-evoked pupil response and the experience of effort and tiredness from listening
Effort and tiredness from listening are common complaints from individuals suffering from declines in hearing and/or cognition. In recent years, pupillometry has emerged as a possible objective tool for measuring the mental effort associated with listening in adverse conditions. However, the precise relationship between changes in the task-evoked pupil response (TEPR) and the subjective experience of listening-related effort and tiredness remains unclear. Data from two experiments are presented that seek to examine the relationship between TEPR and perceived effort and tiredness by measuring covariance in these measures over the course of a sustained effortful listening task. For Experiment 1, we sought to replicate the effect of SNR on TEPR and self-report indices of effort and tiredness from listening during a competing talker task. Results suggest that a more adverse signal-to-noise ratio results in both larger TEPRs and increased self-report effort and tiredness ratings. However, the data also suggest that the effect of SNR on tiredness from listening ratings may be masked when using a single 'pre-post' measure of perceived tiredness. Experiment 2 sought to simulate a more sustained (and thus, fatiguing) challenging listening condition to examine these relationships in more detail. Results suggest that tiredness from listening ratings are related to both perceived effort and TEPR at the level of the individual; higher tiredness ratings are associated with higher effort ratings and smaller TEPRs. No relationship was found between TEPR and perceived effort ratings. Perceived performance was negatively related to both perceived effort and tiredness, suggesting a possible link between the feeling of tiredness from listening and self-efficacy. Theoretical implications of the data are discussed within the Framework for Understanding Effortful Listening (FUEL).