The pupil response reveals increased listening effort when it is difficult to focus attention

• Published in: Hearing research Vol. 323; pp. 81 - 90
• Main Authors: Koelewijn, Thomas, de Kluiver, Hilde, Shinn-Cunningham, Barbara G., Zekveld, Adriana A., Kramer, Sophia E.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.05.2015
• Subjects: Acoustic Stimulation; Adolescent; Adult; Attention; Audiometry, Speech; Blinking; Cognition; Cues; Eye Movements; Female; Humans; Male; Mental Recall; Miosis; Mydriasis; Noise - adverse effects; Perceptual Masking; Pupil - physiology; Reflex, Pupillary; Sound Localization; Speech Intelligibility; Speech Perception; Time Factors; Uncertainty; Young Adult
• ISSN: 0378-5955; 1878-5891; 1878-5891
• DOI: 10.1016/j.heares.2015.02.004

Recent studies have shown that prior knowledge about where, when, and who is going to talk improves speech intelligibility. How related attentional processes affect cognitive processing load has not been investigated yet. In the current study, three experiments investigated how the pupil dilation response is affected by prior knowledge of target speech location, target speech onset, and who is going to talk. A total of 56 young adults with normal hearing participated. They had to reproduce a target sentence presented to one ear while ignoring a distracting sentence simultaneously presented to the other ear. The two sentences were independently masked by fluctuating noise. Target location (left or right ear), speech onset, and talker variability were manipulated in separate experiments by keeping these features either fixed during an entire block or randomized over trials. Pupil responses were recorded during listening and performance was scored after recall. The results showed an improvement in performance when the location of the target speech was fixed instead of randomized. Additionally, location uncertainty increased the pupil dilation response, which suggests that prior knowledge of location reduces cognitive load. Interestingly, the observed pupil responses for each condition were consistent with subjective reports of listening effort. We conclude that communicating in a dynamic environment like a cocktail party (where participants in competing conversations move unpredictably) requires substantial listening effort because of the demands placed on attentional processes. •Specific attentional cues needed for listening in noise were manipulated.•Pupillometry was used to assess the effort required for attentional processes.•Location and talker uncertainty increased the pupil response (listening effort).•Uncertainty about speech onset did not affect listening effort.