Publications by authors named "Søren Kamaric Riis"

3 Publications

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How Do We Allocate Our Resources When Listening and Memorizing Speech in Noise? A Pupillometry Study.

Ear Hear 2021 Jul-Aug 01;42(4):846-859

Eriksholm Research Centre, Oticon A/S, Snekkersten, Denmark.

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.
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August 2021

The CI MuMuFe - A New MMN Paradigm for Measuring Music Discrimination in Electric Hearing.

Front Neurosci 2020 23;14. Epub 2020 Jan 23.

Center for Music in the Brain, Department of Clinical Medicine, Aarhus University and The Royal Academy of Music, Aarhus/Aalborg, Aarhus, Denmark.

Cochlear implants (CIs) allow good perception of speech while music listening is unsatisfactory, leading to reduced music enjoyment. Hence, a number of ongoing efforts aim to improve music perception with a CI. Regardless of the nature of these efforts, effect measurements must be valid and reliable. While auditory skills are typically examined by behavioral methods, recording of the mismatch negativity (MMN) response, using electroencephalography (EEG), has recently been applied successfully as a supplementary objective measure. Eleven adult CI users and 14 normally hearing (NH) controls took part in the present study. To measure their detailed discrimination of fundamental features of music we applied a new multifeature MMN-paradigm which presented four music deviants at four levels of magnitude, incorporating a novel "no-standard" approach to be tested with CI users for the first time. A supplementary test measured behavioral discrimination of the same deviants and levels. The MMN-paradigm elicited significant MMN responses to all levels of deviants in both groups. Furthermore, the CI-users' MMN amplitudes and latencies were not significantly different from those of NH controls. Both groups showed MMN strength that was in overall alignment with the deviation magnitude. In CI users, however, discrimination of pitch levels remained undifferentiated. On average, CI users' behavioral performance was significantly below that of the NH group, mainly due to poor pitch discrimination. Although no significant effects were found, CI users' behavioral results tended to be in accordance with deviation magnitude, most prominently manifested in discrimination of the rhythm deviant. In summary, the study indicates that CI users may be able to discriminate subtle changes in basic musical features both in terms of automatic neural responses and of attended behavioral detection. Despite high complexity, the new CI MuMuFe paradigm and the "no-standard" approach provided reliable results, suggesting that it may serve as a relevant tool in future CI research. For clinical use, future studies should investigate the possibility of applying the paradigm with the purpose of assessing discrimination skills not only at the group level but also at the individual level.
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January 2020

Hearing Device Manufacturers Call for Interoperability and Standardization of Internet and Audiology.

Am J Audiol 2016 Oct;25(3S):260-263

Cochlear Technology Centre, Mechelen, Belgium.

Purpose: This article describes the perspectives of hearing device manufacturers regarding the exciting developments that the Internet makes possible. Specifically, it proposes to join forces toward interoperability and standardization of Internet and audiology.

Method: A summary of why such a collaborative effort is required is provided from historical and scientific perspectives. A roadmap toward interoperability and standardization is proposed.

Results: Information and communication technologies improve the flow of health care data and pave the way to better health care. However, hearing-related products, features, and services are notoriously heterogeneous and incompatible with other health care systems (no interoperability). Standardization is the process of developing and implementing technical standards (e.g., Noah hearing database). All parties involved in interoperability and standardization realize mutual gains by making mutually consistent decisions. De jure (officially endorsed) standards can be developed in collaboration with large national health care systems as well as spokespeople for hearing care professionals and hearing device users. The roadmap covers mutual collaboration; data privacy, security, and ownership; compliance with current regulations; scalability and modularity; and the scope of interoperability and standards.

Conclusions: We propose to join forces to pave the way to the interoperable Internet and audiology products, features, and services that the world needs.
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October 2016