Review of Self-Motion in the Context of Hearing and Hearing Device Research.

The benefit from directional hearing devices predicted in the lab often differs from reported user experience, suggesting that laboratory findings lack ecological validity. This difference may be partly caused by differences in self-motion between the lab and real-life environments. This literature review aims to provide an overview of the methods used to measure and quantify self-motion, the test environments, and the measurement paradigms. Self-motion is the rotation and translation of the head and torso and movement of the eyes. Studies were considered which explicitly assessed or controlled self-motion within the scope of hearing and hearing device research. The methods and outcomes of the reviewed studies are compared and discussed in relation to ecological validity. The reviewed studies demonstrate interactions between hearing device benefit and self-motion, such as a decreased benefit from directional microphones due to a more natural head movement when the test environment and task include realistic complexity. Identified factors associated with these interactions include the presence of audiovisual cues in the environment, interaction with conversation partners, and the nature of the tasks being performed. This review indicates that although some aspects of the interactions between self-motion and hearing device benefit have been shown and many methods for assessment and analysis of self-motion are available, it is still unclear to what extent individual factors affect the ecological validity of the findings. Further research is required to relate lab-based measures of self-motion to the individual's real-life hearing ability.