Sensitivity, reliability and convergent validity of sequential dual-task measures of listening effort

The aim of the current study was to assess the sensitivity, reliability and convergent validity of objective measures of listening effort collected in a sequential dual-task. On each trial, participants viewed a set of digits and listened to a spoken sentence presented at one of a range of signal-to-noise ratios (SNR) and then typed the sentence-final word and recalled the digits. Listening effort measures included word response time, digit recall accuracy and digit response time. In Experiment 1, SNR on each trial was randomised. In Experiment 2, SNR varied in a blocked design, and in each block self-reported listening effort was also collected. Separate groups of 40 young adults participated in each experiment. Effects of SNR were observed for all measures. Linear effects of SNR were generally observed even with word recognition accuracy factored out of the models. Among the objective measures, reliability was excellent, and repeated-measures correlations, though not between-subjects correlations, were nearly all significant. The objective measures assessed appear to be sensitive and reliable indices of listening effort that are non-redundant with speech intelligibility and have strong within-participants convergent validity. Results support use of these measures in future studies of listening effort.