Dorothea Wendt

Scientist, PostDoc

Cognitive resources are required for understanding, responding to, and memorising speech. In this study, the aim is to get a better understanding of these cognitive processes in Cochlear Implant users.
Everyday communication can be demanding in particular for people with hearing impairment. Cognitive resources are required not only for understanding what was said but also for responding or memorising speech in a conversation. Research has demonstrated that higher cognitive processes, such as working memory (WM) or attention, are involved in communicating. Background noise can affect those cognitive processes including listening effort, which has been defined as ‘the deliberate allocation of mental resources to overcome obstacles to goal pursuit when carrying out a listening task’ (Pichora-Fuller et al., 2016).

Towards a better understanding of cognitive processes

This study is part of a PhD project by Hanna Bönitz on “Cognitive ability & listening effort – a study on post-lingually deafened CI users” in cooperation with the Medical School in Hanover, Linköping University, Oticon Medical and Eriksholm Research Centre.

The goal of this project is toward a more comprehensive understanding of cognitive processes involved in listening and memorising speech in Cochlear Implant (CI) users. To investigate listening effort and memory processing during speech processing, two different methods have been combined in the current project. A physiological measure, i.e. the pupillary response, has been applied during a memory task called the Sentence Final Word Identification task (SWIR, Ng et al. 2013, 2015). The measurement of the pupil dilation has been demonstrated to be a valid method to quantify listening effort required in speech understanding. Furthermore, the pupil diameter has been associated with task load and cognitive processing, as it enlarges with increasing task difficulty.


In the SWIR test sentences were presented, and participants were asked to repeat the last word of the sentence. In the recall condition, participants additionally had to recall all final words after all sentences were presented. While performing the SWIR, participants’ pupil size was recorded with an eye-tracking camera. The pupil size was expected to increase with increasing task demands, i.e. in the recall compared to the no-recall condition, due to higher effort.


Preliminary results for CI users: Pupillary response during the SWIR test without (in red) and with (in red) including the recall task.

Preliminary results

The figure shows preliminary data indicating that the pupil dilation is following the sentence presentation systematically. The pupil dilates as soon as a sentence (Sen1- Sen6) was presented and, thus, indexing the allocation of resources while listening to the sentence. Furthermore, larger pupil dilations could be found when recalling the words (in the recall condition) indicating the amount of resources utilized for memorizing the speech.

Interestingly, effort already increased during the repetition phase (while repeating sentence 4 to 6) in the recall condition compared to the no-recall condition. Initial results seem promising when it comes to qualifying processing effort in CI users by means of pupil size dilation during the SWIR test.

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    Cochlear Implant Users and their ability to memorize and recall speech in noisy environment