Eye movements decrease during effortful speech listening

Pupillometry is the most used objective tool to assess listening effort but has several disadvantages. The current study explores a new, objective way to assess listening effort through eye movements. Building on cognitive and neurophysiological work, we examine the hypothesis that eye movements decrease when speech listening becomes challenging. In three experiments with human participants from both sexes, we demonstrate, consistent with this hypothesis, that fixation duration increases and spatial gaze dispersion decreases with increasing speech masking. Eye movements decreased during effortful speech listening for different visual scenes (free viewing; object tracking) and speech materials (simple sentences; naturalistic stories). In contrast, pupillometry was insensitive to speech masking during story listening, highlighting the challenges with pupillometric measures for the assessments of listening effort in naturalistic speech-listening paradigms. Our results reveal a critical link between eye movements and cognitive load, and provide the foundation for a novel measure of listening effort applicable in a wide range of contexts. Significance statement Assessment of listening effort is critical for early diagnosis of age-related hearing loss. Pupillometry is most used but has several disadvantages. The current study explores a new, objective way to assess listening effort through eye movements. We examine the hypothesis that eye movements decrease when speech listening becomes effortful. We demonstrate, consistent with this hypothesis, that fixation duration increases and gaze dispersion decreases with increasing speech masking. Eye movements decreased during effortful speech listening for different visual scenes (free viewing; object tracking) and speech materials (sentences; naturalistic stories). Our results reveal a critical link between eye movements and cognitive load, and provide the foundation for a novel measure of listening effort applicable in a wide range of contexts.