Just Keep Spinning? The Impact of Auditory and Somatosensory Cues on Rotary Chair Testing.

PURPOSE: The purpose of this study was to determine whether providing realistic auditory or somatosensory cues to spatial location would affect measures of vestibulo-ocular reflex gain in a rotary chair testing (RCT) context. METHOD: This was a fully within-subject design. Thirty young adults age 18-30 years (16 men, 14 women by self-identification) completed sinusoidal harmonic acceleration testing in a rotary chair under five different conditions, each at three rotational frequencies (0.01, 0.08, and 0.32 Hz). We recorded gain as the ratio of the amplitude of eye movement to chair movement using standard clinical procedures. The five conditions consisted of two without spatial information (silence, tasking via headphones) and three with either auditory (refrigerator sound, tasking via speaker) or somatosensory (fan) information. Two of the conditions also included mental tasking (tasking via headphones, tasking via speaker) and differed only in terms of the spatial localizability of the verbal instructions. We used linear mixed-effects modeling to compare pairs of conditions, specifically examining the effects of the availability of spatial cues in the environment. This study was preregistered on Open Science Framework (https://osf.io/2gqcf/). RESULTS: Results showed significant effects of frequency in all conditions (p < .05), but the only pairs of conditions that were significantly different were those including tasking in one condition but not the other (e.g., tasking via headphones vs. silence). Post hoc equivalence testing showed that the lack of significance in the other comparisons could be confirmed as not meaningfully different. CONCLUSIONS: These findings suggest that the presence of externally localizable sensory information, whether auditory or somatosensory, does not affect measures of gain in RCT to any relevant degree. However, these findings also contribute to the increasing body of evidence suggesting that mental engagement ("tasking") does increase gain whether or not it is provided via localizable instructions.

Fall-Related Injuries Mediate the Relationship Between Self-Reported Hearing Loss and Mortality in Middle-Aged and Older Adults.

BACKGROUND: Hearing loss is associated with a greater risk of death in older adults. This relationship has been attributed to an increased risk of injury, particularly due to falling, in individuals with hearing loss. However, the link between hearing loss and mortality across the life span is less clear. METHODS: We used structural equation modeling and mediation analysis to investigate the relationship between hearing loss, falling, injury, and mortality across the adult life span in public-use data from the National Health Interview Survey and the National Death Index. We examined (a) the association between self-reported hearing problems and later mortality, (b) the associations between self-reported hearing problems and the risk of injury and degree and type of injury, (c) the mediating role of falling and injury in the association between self-reported hearing problems and mortality, and (d) whether these relationships differ in young (18-39), middle-aged (40-59), and older (60+) age groups. RESULTS: In all 3 age ranges, those reporting hearing problems were more likely to fall, were more likely to sustain an injury, and were more likely to sustain a serious injury, than those not reporting hearing problems. While there was no significant association between hearing loss and mortality in the youngest category, there was for middle-aged and older participants, and for both, the fall-related injury was a significant mediator in this relationship. CONCLUSIONS: Fall-related injury mediates the relationship between hearing loss and mortality for middle-aged as well as older adults, suggesting a need for further research into mechanisms and remediation.