Comparison of Psychophysiological and Dual-Task Measures of Listening Effort

We wished to make a comparison of psychophysiological measures of listening effort with subjective and dual-task measures of listening effort for a diotic-dichotic-digits and a sentences-in-noise task.

Three groups of young adults (18-38 years old) with normal hearing participated in three experiments: two psychophysiological studies for two different listening tasks and a dual-task measure for a sentences-in-noise task. Psychophysiological variables included skin conductance, heart-rate variability, and heart rate; the dual-task measure was a letter-identification task. Heart-rate variability was quantified with the difference from baseline for the normalized standard deviation of R to R.

Heart-rate variability differences from baseline were greater for increased task complexity and for poorer signal-to-noise ratios (SNRs). The dual-task measure of listening effort also increased for sentences presented at a +5 dB SNR compared with a +15 dB SNR. Skin conductance was elevated for greater task complexity only, and similar across noise conditions. None of these measures were significantly correlated with subjective measures of listening effort.

Heart-rate variability appears to be a robust psychophysiological indicator of listening effort, sensitive to both task complexity and SNR. This sensitivity to SNR was similar to a dual-task measure of listening effort.