Exploring the Effects of Copresence During Speech-in-Noise Perception
Authors:   , Pielage Hidde 
Published: February 2024

Hearing loss (HL) is highly prevalent among the world population. While many methods are available that assess HL and the impact it has on individuals, recently there has been a call for assessment methods that better reflect “real-life hearing-related function, activity, or participation”. Such methods provide a clearer picture of the daily life difficulties associated with HL and aid the development and evaluation of hearing solutions. This thesis considers how the copresence of other persons might play a role during real-life listening situations. Not only does listening commonly take place in the presence of others (e.g. conversations), having others copresent often influences human behaviour and cognitive processes. This raises the question as to whether listening is also affected by copresence. We added a copresence manipulation to existing audiological assessment methods and examined the effects on performance and listening effort. The latter was measured both objectively using pupillometry or cardiovascular outcomes, and subjectively using questionnaires. We also examined the effect of copresence in a virtual reality environment. Virtual reality allows researchers (and clinicians) to more accurately simulate real-life listening conditions while also maintaining high degrees of experimental control, and at a relatively low cost.

The studies described in this thesis found that copresence can affect listening effort and/or arousal. This is an important insight as copresence is often part of real-life listening situations, but rarely considered in hearing research and tests. Insights such as these can aid the development of hearing assessment methods that better reflect real-life and thereby provide a better benchmark for hearing solutions. Interestingly, copresence did not affect listening performance, even though previous studies have often found that copresence influences performance on a wide array of tasks. The studies described in this thesis made the first steps toward considering copresence in hearing research and provided useful tools and a methodological basis for future research. Inevitably, copresence in real-life is much more complex and multifaceted. For example, we did not consider how the nature of the relationship between a listener and copresence person might alter copresence effects. Furthermore, we do not yet know if it matters whether speech originates from a social (copresent) source or not, which would be an important next step for future research. Furthermore, the studies described in this thesis used a small set of performance and effort measures, expanding on this set in future studies may allow for deeper understanding of copresence effects. Finally, if the aim is to better understand how copresence affects persons with hearing loss, future studies should also consider directly comparing normal hearing participants and participants with hearing loss.
Virtual reality can be successfully combined with SiN research. Pupil size measures taken from within head mounted displays seem to adequately reflect SiN related effort. While there are no physical limitations to use cardiovascular measurements combined with virtual reality, it is not clear if they can appropriately index effort in this context. Furthermore, while virtual reality is a promising tool for SiN tests that better reflect real life, more advanced virtual environments may be required to accurately simulate copresence.