Effects of age and task difficulty on ERP responses to novel sounds presented during a speech-perception-in-noise test

OBJECTIVE: Event-related potentials (ERPs) to task-irrelevant novel sounds have been shown to increase in amplitude with increasing task difficulty and might therefore reflect listening effort. Here we investigated whether this effect is similar in two groups of younger and older listeners with normal hearing. METHODS: Novel sounds were presented during a speech-perception-in noise test and task difficulty was adjusted decreasing the signal-to-noise ratio (SNR) relative to the individual 50% correct speech recognition SNR (easy +10 dB, medium +2dB, hard 0 dB). RESULTS: Amplitudes of the Novelty P3 and a late positive potential (LPP) were significantly larger in younger compared to older participants. Novelty P3 amplitude increased with increasing task difficulty in both age groups, but the effect was more robust in younger listeners. By contrast, LPP amplitude increases were observed only in older listeners. CONCLUSIONS: Novelty P3 and LPP were found to be differently affected by task difficulty in the two age groups indicating sustained and more effortful processing under challenging listening conditions in older listeners. SIGNIFICANCE: These results confirmed the potential use of novel sounds during an auditory task as an indirect measure of listening effort in younger and older listeners, but the different focus on Novelty P3 and LPP should be taken into account.