Objective assessment of listening effort: effects of an increased task demand.

In demanding listening situations the individual has to exert an increased listening effort to process interesting auditory signals correctly. Especially people with hearing loss are particularly affected and require more effort to identify sounds compared to those with normal hearing. So far, a suitable objective estimate of listening effort is still not available. In previous studies, we presented an objective estimate of listening effort (OLEosc), which is based on the instantaneous phase distribution of the ongoing EEG activity. In the current study, the proposed measure was analyzed in detail. The task performance was taken into account, which indicates if the participants can solve the auditory task and exert effort or if they ceased solving the task. The EEG data was acquired from people with moderate hearing loss solving a listening task. During the experiment, hearing aid settings with different microphone configurations were tested. The results indicate that the OLEosc reflects the real exerted effort of the participants. Besides the reflection of different task demands related to the hearing aid settings, it was possible to show a decline of focused attention to the auditory stimuli related to an excessive task demand. Furthermore, the data indicate that the OLEosc is not directly correlated to the speech intelligibility presented in the word score data and is not subjectively biased like the results of the presented rating scale.