Hanna Bönitz1, Thomas Lunner2,3, Mareike Finke1,4, Lorenz Fiedler3, Björn Lyxell2,5, Søren Kamaric Riis6, Elaine Ng2,7, Alejandro Lopez Valdes3, Andreas Büchner1,4, Dorothea Wendt3,8. 1. Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany. 2. Department of Behavioral Sciences and Learning, Linnaeus Centre HEAD, Swedish Institute for Disability Research, Department of Behavioral Sciences and Learning, Linköping University, Linköping, Sweden. 3. Eriksholm Research Centre, Oticon A/S, Snekkersten, Denmark. 4. Cluster of Excellence "Hearing4all", Hannover, Germany. 5. Department of Special Needs Education, Oslo University, Oslo, Norway. 6. Oticon Medical A/S, Kongebakken, Denmark. 7. Oticon A/S, Smørum, Denmark. 8. Hearing Systems, Department of Health Technology, Technical University of Denmark, Denmark.
Abstract
OBJECTIVES: Actively following a conversation can be demanding and limited cognitive resources must be allocated to the processing of speech, retaining and encoding the perceived content, and preparing an answer. The aim of the present study was to disentangle the allocation of effort into the effort required for listening (listening effort) and the effort required for retention (memory effort) by means of pupil dilation. DESIGN: Twenty-five normal-hearing German speaking participants underwent a sentence final word identification and recall test, while pupillometry was conducted. The participants' task was to listen to a sentence in four-talker babble background noise and to repeat the final word afterward. At the end of a list of sentences, they were asked to recall as many of the final words as possible. Pupil dilation was recorded during different list lengths (three sentences versus six sentences) and varying memory load (recall versus no recall). Additionally, the effect of a noise reduction algorithm on performance, listening effort, and memory effort was evaluated. RESULTS: We analyzed pupil dilation both before each sentence (sentence baseline) as well as the dilation in response to each sentence relative to the sentence baseline (sentence dilation). The pupillometry data indicated a steeper increase of sentence baseline under recall compared to no recall, suggesting higher memory effort due to memory processing. This increase in sentence baseline was most prominent toward the end of the longer lists, that is, during the second half of six sentences. Without a recall task, sentence baseline declined over the course of the list. Noise reduction appeared to have a significant influence on effort allocation for listening, which was reflected in generally decreased sentence dilation. CONCLUSION: Our results showed that recording pupil dilation in a speech identification and recall task provides valuable insights beyond behavioral performance. It is a suitable tool to disentangle the allocation of effort to listening versus memorizing speech.
OBJECTIVES: Actively following a conversation can be demanding and limited cognitive resources must be allocated to the processing of speech, retaining and encoding the perceived content, and preparing an answer. The aim of the present study was to disentangle the allocation of effort into the effort required for listening (listening effort) and the effort required for retention (memory effort) by means of pupil dilation. DESIGN: Twenty-five normal-hearing German speaking participants underwent a sentence final word identification and recall test, while pupillometry was conducted. The participants' task was to listen to a sentence in four-talker babble background noise and to repeat the final word afterward. At the end of a list of sentences, they were asked to recall as many of the final words as possible. Pupil dilation was recorded during different list lengths (three sentences versus six sentences) and varying memory load (recall versus no recall). Additionally, the effect of a noise reduction algorithm on performance, listening effort, and memory effort was evaluated. RESULTS: We analyzed pupil dilation both before each sentence (sentence baseline) as well as the dilation in response to each sentence relative to the sentence baseline (sentence dilation). The pupillometry data indicated a steeper increase of sentence baseline under recall compared to no recall, suggesting higher memory effort due to memory processing. This increase in sentence baseline was most prominent toward the end of the longer lists, that is, during the second half of six sentences. Without a recall task, sentence baseline declined over the course of the list. Noise reduction appeared to have a significant influence on effort allocation for listening, which was reflected in generally decreased sentence dilation. CONCLUSION: Our results showed that recording pupil dilation in a speech identification and recall task provides valuable insights beyond behavioral performance. It is a suitable tool to disentangle the allocation of effort to listening versus memorizing speech.