Regina C. Calloway1, Lien Decruy1, I. M. Dushyanthi Karunathilake2, Jason L. Dunlap3, Samira Anderson3, Jonathan Z. Simon1,2,4, Stefanie E. Kuchinsky5
1Institute for Systems Research
2Department of Electrical and Computer Engineering
3Department of Hearing and Speech Sciences
4Department of Biology, University of Maryland, College Park, U.S.A.
5Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, U.S.A

Understanding speech in noisy environments is important in everyday life and requires effortful listening. Older adults’ listening effort may be especially affected by noise, associated with a diminished ability to effectively track a target speaker among background speakers across longer periods of time. To further understand how different listening situations influence older adults’ ability to sustain effort to meaningful speech, the present study used 60-second audiobook segments. This experiment investigated the effect of 1) different signal-to-noise ratios (SNRs: quiet, 0dB, or -6dB) and 2) number of audiobook repetitions (three times each in the two noisy conditions) on listening effort, for 13 older adults with clinically normal hearing. We hypothesized that poorer SNRs would result in increased listening effort and that increased number of repetitions would result in decreased listening effort. Participants heard the audiobook segments while pupillary measures were recorded, with larger pupil dilations indicating greater listening effort. Generalized additive mixed model (GAMM) results revealed that these older listeners showed evidence of increased listening effort in the noisy conditions and decreased listening effort between the first and second presentation. The temporal precision of pupillometry measures also indexed time-specific changes in listening effort, with increased effort at the beginning and end of the audiobook segments. Furthermore, listening effort varied nonlinearly with listeners’ subjective intelligibility ratings of each SNR block. In comparison to the quiet condition, listening effort in the noisy conditions was associated with higher self-reported intelligibility ratings, suggesting that individuals only engaged in listening to speech that was at least moderately intelligible. Taken together, our findings illustrate how SNR and repetition influence listening effort when listening to sustained, continuous speech and how effort can deviate from intelligibility in some listening conditions. Thus, this study aims to provide an ecologically valid account of older adults’ sustained listening effort.

Acknowledgements: This work was supported by the National Institutes of Health (P01- AG055365). The views expressed in this abstract are those of the author and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or U.S. Government.