Quantification of listening effort correlates in the oscillatory EEG activity: a feasibility study

So far, a generally accepted objective measure for the listening effort estimation in clinical settings is not existent. Such a measure could support the hearing aid fitting in order to reduce the listening effort in hearing impaired patients by an adequate adaption of their personal hearing aids. In the current study, we propose a new measure for the quantification of large-scale listening effort correlates. This measure takes the phase information of the ongoing oscillatory EEG activity into account. The phase was gained from the 32 channel EEG. Then, the entropy of the extracted phase was calculated. We assume that this angular entropy reflects phase synchronization effects of the ongoing activities due to an increased attention on the relevant (speech) signal. Thus, we expect that smaller values of the angular entropy reflect a more "ordered" process of the phase distribution. The new method was tested in 13 young normal hearing subjects using different auditory tasks consisting of differently adapted sentences to create different listening conditions. The results indicate that the angular entropy can be applied to reveal significantly differences between the solving and the relaxing part of the paradigm, i.e. between a more effortful and a more relaxing listening situation. It is concluded, that the further research includes the development of more effortful listening tasks in order to reveal also differences between the auditory paradigms.