Are the Physiological Measures SpO2 and Heart Rate Biological Markers for Listening Effort and Fatigue?

Abstract To investigate whether physiological measures such as oxygen saturation (SpO2) and heart rate can reliably indicate listening effort and fatigue as well as possibly serve as objective alternatives to traditional subjective reports in the evaluation of the effects of digital noise reduction (DNR) in hearing aids. Through a repeated-measures design, we evaluated listening effort and fatigue in 35 participants with mild-to-moderately-severe sensorineural hearing loss using hearing aids, under DNR-on and DNR-off conditions. The participants performed a dual task for us to assess listening effort and fatigue, and physiological data (SpO2 and heart rate) were recorded with a pulse oximeter during the pretask, task, and posttask phases. Subjective ratings of listening effort, fatigue, attention, and concentration were obtained via self-report scales to assess DNR effectiveness and physiological marker sensitivity. In DNR on, a significantly-higher score on repetition and recall was observed, along with reduced listening effort and reaction time, compared with DNR off. The posttest scores showed that the participants reported significantly less listening effort and fatigue, with improved attention and concentration in DNR on than in the pretest, whereas the opposite was true in the off condition. A notable difference in heart rates was observed between the pre- and post-test phases in DNR on. The median SpO2 levels significantly increased from the pre- to the post-task phases, with a notable difference during the task phase as well. Additionally, a negative correlation was found between fatigue and SpO2 in DNR on, while a positive relationship was noted between attention and SpO2 in DNR off. Physiological measures, particularly SpO2, show preliminary promise as potential objective markers of listening effort and fatigue, aligning with behavioral and subjective outcomes, but this requires further validation.