Automatic Detection of Gait Perturbations With Everyday Wearable Technology

Falls are a significant health problem in older people, so preventing them is essential. Since falls are often a consequence of improper reaction to gait disturbances, such as slips and trips, their detection is gaining attention in research. However there are no studies to date that investigated perturbation detection, using everyday wearable devices like hearing aids or smartphones at different body positions. Sixty-six study participants were perturbed on a split-belt treadmill while recording data with hearing aids, smartphones, and professional inertial measurement units (IMUs) at various positions (left/right ear, jacket pocket, shoulder bag, pants pocket, left/right foot, left/right wrist, lumbar, sternum). The data were visually inspected and median maximum cross-correlations were calculated for whole trials and different perturbation conditions. The results show that the hearing aids and IMUs perform equally in measuring acceleration data (correlation coefficient of 0.93 for the left hearing aid and 0.99 for the right hearing aid), which emphasizes the potential of utilizing sensors in hearing aids for head acceleration measurements. Additionally, the data implicate that measurement with a single hearing aid is sufficient and a second hearing aid provides no added value. Furthermore, the acceleration patterns were similar for the ear position, the jacket pocket position, and the lumbar (correlation coefficient of about 0.8) or sternal position (correlation coefficient of about 0.9). The correlations were found to be more or less independent of the type of perturbation. Data obtained from everyday wearable devices appears to represent the movements of the human body during perturbations similar to that of professional devices. The results suggest that IMUs in hearing aids and smartphones, placed at the trunk, could be well suited for an automatic detection of gait perturbations.

Falls and their sequelae cost more than $50 billion every year. Older adults with hearing loss are at 2.4 times greater risk of falls than their normal hearing peers. Current research is inconclusive about whether hearing aids can offset this increased fall risk, and no previous studies considered if outcomes differed based on the consistency of hearing aid use. Individuals 60 years and older with bilateral hearing loss completed a survey consisting of the Fall Risk Questionnaire (FRQ) and questions about hearing loss history, hearing aid use, and other common fall risk factors. In this cross-sectional study, fall prevalence, as well as fall risk (based on FRQ score), was compared between hearing aid users and non-users. A separate group of consistent hearing-aid users (at least 4 h daily use for more than 1 year) was also compared with inconsistent/non-users. Responses from 299 surveys were analyzed. Bivariate analysis found 50% reduced odds of experiencing a fall for hearing aid users compared with non-users (OR = 0.50 [95% CI: 0.29-0.85], p = 0.01). After adjusting for age, sex, hearing loss severity, and medication usage, those who reported any hearing aid use still had lower odds of falls (OR = 0.48 [95% CI: 0.26-0.90], p = 0.02) and lower odds of being at risk for falls (OR = 0.36 [95% CI: 0.19-0.66] p < 0.001) than non-users. Results for consistent hearing aid users demonstrate an even stronger association of lowered odds of falling (OR = 0.35 [95% CI: 0.19-0.67], p < 0.001) and lower odds of being at risk for falls (OR = 0.32 [95% CI: 0.12-0.59], p < 0.001), suggesting a potential dose-response relationship. These findings suggest that use of hearing aids-especially consistent hearing aid use-is associated with lower odds of experiencing a fall or being classified as at risk for falls in older individuals with hearing loss.

Unexpected changes during gait challenge elderly individuals to a greater degree than young adults. However, the adaptive potential of elderly seems to be retained, and therefore, the training of the mechanisms of dynamic stability as well as muscle strength training may improve the dynamic stability after unexpected perturbations. Thirty-eight subjects (65-75 years) participated in the study, divided into two experimental groups (stability training group, ST, n = 14 and mixed training group, MT, n = 14) and a control group (CG, n = 10). Both experimental groups performed exercises which focused on the mechanisms of dynamic stability. Additionally, the MT group executed a training to improve muscle strength. Session volume and duration were equal for both groups (14 weeks, twice a week, ~1.5 h per session). Pre- and post-intervention, subjects performed a gait protocol with an induced unexpected perturbation. Post-intervention, the margin of stability was significantly increased after the unexpected perturbation in the ST group, indicating an improvement in stability state (pre, -30.3 ± 5.9 cm; post, -24.1 ± 5.2 cm). Further, both intervention groups increased their base of support after the intervention to regain balance after gait perturbation, whereas only the ST group showed a statistically significant improvement (STpre, 90.9 ± 6.6 cm, STpost, 98.2 ± 8.5 cm; MTpre, 91.4 ± 6.2 cm; MTpost, 97.9 ± 12.7 cm). The CG showed no differences between pre- and post-measurements. The exercise of the mechanisms of dynamic stability led to a better application of these mechanisms after an unexpected perturbation during gait. We suggest that the repeated exercise of the mechanisms of dynamic stability contributes to significant improvements in postural stability. Additional strength training for healthy elderly individuals, however, shows no further effect on the ability to recover balance after unexpected perturbations during gait.

Young and old adults prioritize dynamic stability control following gait perturbations when performing a concurrent cognitive task

The aim of this study was to document postural control, sensory organization, and fall risk parameters of auditory input using computerized posturography in bilaterally hearing-aided young adults. A total of 54 individuals aged 18 to 40 years participated in the study, including 36 bilateral hearing aid (HA) users and 18 normal-hearing controls. HA users were divided into two groups based on the duration of device use: Group 1 included individuals using bilateral HAs for 12 months or less, and Group 2 included those using them for more than 12 months. The Sensory Organization Test (SOT) and computerized Fall Risk Assessment were administered to all participants meeting the inclusion criteria. Group 1 and Group 2 were assessed under both HA-on and HA-off conditions, while the control group was evaluated only under auditory stimulation. SOT Condition 1, 2, and 4 scores of Group 1 in the HA-on situation were statistically significantly higher than in the HA-off situation. No statistically significant difference was observed in Condition 3, 5, and 6 scores. All SOT condition scores in the HA-on situation of Group 2 were statistically significantly higher than those in the HA-off situation. It was observed that the risk of falling performance was riskier when the HAs were turned off in Group 1 and Group 2 compared to when the HAs were turned on. It was observed that auditory input had a positive contribution to postural control and fall risk in young adult HA users.

The aim is to presents a solution and realization of the design of new split-belt treadmill for controlled, unexpected perturbation during walking to study recovery responses and dynamic stability of the human gait. The construction of the split-belt treadmill consists of several subsystems. The most important subsystems are: actuator, control and sensory subsystem. Actuator subsystem is based on two asynchronous motors, two inverters and two gears (for each belt separately). Control subsystem is made up of Modbus communications between the control computer and two inverters with respect to the parameters of the asynchronous motors. The sensory subsystem is based on the incremental angular speed sensor used to record the behavior of the treadmill belts. The control itself is created through the MatLab software and special custom-made user interface that allows to define a wide range of perturbation schemes. It was then verified whether the belts had the desired speed. Verification of the system has shown that at the recommended speeds of running the belts (at 2.4 km/h), the system is stable, shows no variations in proband load, and real changes in belt velocities are achieved with minimum deviations from the desired values. The main benefit of the described work is the creation of a functional control of the prototype of the treadmill for controlled, mechanical gait perturbations. The split-belt treadmill is designed to study reactive responses during walking that can be further used to fall-risk assessment, clinical or rehabilitation intervention.

Purpose Hearing loss is a risk factor for falls. The purpose of this study was to investigate the relation between subjective hearing difficulty and risk of falls. Method Community-dwelling older adults, aged 60 years and older, completed a case history; three questionnaires, including the Hearing Handicap Inventory for the Elderly (HHIE), Dizziness Handicap Inventory (DHI), Activities-Specific Balance Confidence Scale (ABC); and one functional balance measure, the Timed Up and Go (TUG) test. Pearson and Spearman correlations were calculated, and average scores were plotted according to group and HHIE score category for DHI, ABC, TUG, the number of medications, and the number of recent falls. Results Seventy-four participants were included in this analysis: 28 nonaudiology patients, 18 audiology patients with hearing aids, and 28 audiology patients without hearing aids. Significant positive correlations were noted between HHIE and DHI scores for audiology patients without hearing aids and between HHIE score and number of recent falls for audiology patients with hearing aids. When average scores were plotted for DHI, ABC, TUG, the number of medications, and the number of recent falls according to group and category, there were clear trends toward increased fall risk as HHIE score categories increased (i.e., mild to moderate to severe) based on previously used criteria. Conclusions Overall, a trend was noticed such that, for increasing HHIE score categories, fall risk increased. Significant correlations existed between HHIE score and some of the measures used to indicate fall risk (i.e., DHI score, number of recent falls). Future fall risk research should investigate subjective hearing difficulty as a risk factor, as well as pure-tone audiometric thresholds.

We propose a co-simulation framework comprising biomechanical human body models and wearable inertial sensor models to analyse gait events dynamically, depending on inertial sensor type, sensor positioning, and processing algorithms. A total of 960 inertial sensors were virtually attached to the lower extremities of a validated biomechanical model and shoe model. Walking of hemiparetic patients was simulated using motion capture data (kinematic simulation). Accelerations and angular velocities were synthesised according to the inertial sensor models. A comprehensive error analysis of detected gait events versus reference gait events of each simulated sensor position across all segments was performed. For gait event detection, we considered 1-, 2-, and 4-phase gait models. Results of hemiparetic patients showed superior gait event estimation performance for a sensor fusion of angular velocity and acceleration data with lower nMAEs (9%) across all sensor positions compared to error estimation with acceleration data only. Depending on algorithm choice and parameterisation, gait event detection performance increased up to 65%. Our results suggest that user personalisation of IMU placement should be pursued as a first priority for gait phase detection, while sensor position variation may be a secondary adaptation target. When comparing rotatory and translatory error components per body segment, larger interquartile ranges of rotatory errors were observed for all phase models i.e., repositioning the sensor around the body segment axis was more harmful than along the limb axis for gait phase detection. The proposed co-simulation framework is suitable for evaluating different sensor modalities, as well as gait event detection algorithms for different gait phase models. The results of our analysis open a new path for utilising biomechanical human digital twins in wearable system design and performance estimation before physical device prototypes are deployed.

Falls during walking are a major cause of poststroke injury, and walking faster may decrease the ability to recover following a gait perturbation. We compared gait stability between high-functioning poststroke individuals and controls and evaluated the effect of gait speed on gait stability. Ten stroke subjects and ten age-matched controls walked on a self-paced treadmill at two speeds (matched/faster). Movement of the nonparetic/dominant leg was arrested unexpectedly at early swing. Poststroke individuals lowered the perturbed leg following perturbation (58% of cases) while controls maintained the leg elevated (49% of cases; P < 0.01). In poststroke individuals, double-support duration was restored later than in controls (4.6 ± 0.8 vs. 3.2 ± 0.3 strides; P < 0.007), and long-term phase shifts of arm and leg movements were larger and less coordinated on the paretic side. A moderate speed increase (~20%) enhanced the incidence of leg lowering in controls but not in stroke subjects. Faster walkers in both groups had a more coordinated response, limited to the nonparetic side in the stroke group. However, faster walkers were not more stable following perturbation. Our results suggest that gait perturbations can target basic control processes and identify neurological locomotor deficits in individuals with fall risk. Central regulation of body translation in space is involved in recovery of steady-state walking. Impaired descending control (stroke) decreases the ability of the motor system to recover from perturbations and regulate interlimb phase relationships, especially when changing gait speed. However, interlimb coordination may not be a major factor in the recovery of gait stability.

15 Principles of Consumer-Oriented Audiologic/Aural Rehabilitation

Introduction: Falls and gait disorders often result in hospitalization and immobilization. Near-falls may be one of the earliest signs of increased fall risk. In the literature, several sensor positions are used for fall detection, but few studies include the head as a sensor position. Hearables and hearing aids are increasingly equipped with inertial measurement units (IMUs) and are therefore of particular interest for measuring the risk of falling in everyday life. Methods: Therefore, we investigate the suitability of the ear as a sensor position for near-fall detection in comparison to the standard sensor positions. The motion data of one study participant (female, 63 years) was exemplary analyzed. The participant walked at her individually preferred gait speed on a perturbation treadmill while nine different perturbations (anterior-posterior, medio-lateral and pitch) were applied with a time interval of 20-30 seconds. We used seven IMUs during the measurement at the positions ear, sternum, lumbar, wrist (left/right), foot (left/right). Results: The absolute acceleration signals at the seven different positions show the periodicity of the normal gait before the perturbation. During and after the perturbation changes in the motion pattern can be seen, whereby the response to the perturbation occurs with a slight time lag. The Pearson correlations show that the sensor positions sternum, lumbar and ear correlate well with each other and thus show similar signal characteristics in the reaction to this perturbation. Conclusion: This provides evidence that the ear sensor position is at least comparable to the preferred sensor positions in the literature on the torso. However, these results were obtained under laboratory conditions. Further research is needed to investigate the sensor position at the ear in everyday life.

Hearing loss is associated with increased fall risk in older adults, but multiple mechanisms have been proposed to account for this. Hearing loss may reduce spatial awareness and/or increase cognitive load, both of which may increase fall risk but may be ameliorated by hearing aid use. Here, we present preliminary results from an in-progress study comparing fall incidence in daily life with postural sway measured under various listening conditions in older adults with and without hearing aids. Seventeen adults aged 65 to 81 years (7 using bilateral hearing aids, 10 without) stood with feet together and eyes closed, listening to noise vocoded speech (4, 8, 16 channels) and spatially distributed environmental sounds (silence, 1, 3 sources) for 1min per condition while postural sway was recorded in the lab. Participants subsequently reported daily near-falls and falls for 4 months. Results suggest hearing aid users show less postural sway, potentially indicating greater rigidity which has been associated with greater fall risk. However, near-fall incidence was lower for hearing aid users. Further analyses showed higher near-fall rates associated with higher auditory thresholds, but hearing aid use may mitigate this trend. We are currently collecting more data with a wider variety of participants.

Purpose Falls are considered a significant public health issue, and hearing loss has been shown to be an independent risk factor for falls. The primary objective of this study was to determine if hearing aid use modified (reduced) the association. We hypothesized that routine hearing aid use would reduce the impact of hearing loss on the odds of falling. If hearing aid users have reduced odds of falling, then that would have an important impact on falls prevention health care. Method Data from 8,091 individuals 40 years of age and older who completed National Health and Nutrition Examination Survey (NHANES) cycles 1999-2004 were used. NHANES comprises a series of cross-sectional studies, each of which is representative of the total civilian noninstitutionalized population of children and adults in the United States, enabling unbiased national estimates of health that can be independently reproduced. Self-reported hearing, hearing aid status, falls history, and comorbidities were extracted and analyzed using regression modeling. Results The 8,091 individuals were grouped based on a self-reported history of falls in the last year. Self-reported hearing loss was significantly associated with odds of falling. Categorizing individuals based on routine hearing aid use was included as an interaction term in the fully adjusted models and was not significant, suggesting no difference in falls based on hearing aid status. Conclusions The unique results of the current study show that when examining self-reported hearing in a nationally representative sample, hearing aid use does not appear to mitigate or modify the association between self-reported hearing and falls. Future research designs are highlighted to address limitations identified using NHANES data for this research and focus on the use of experimental designs to further understand the association between hearing loss and falls, including whether hearing loss may be a modifiable risk factor for falls. Supplemental Material https://doi.org/10.23641/asha.14642784.

Gait perturbation response in chronic anterior cruciate ligament deficiency and repair

ObjectiveThis study aimed to explore the association between hearing loss severity, hearing aid use, and subjective memory complaints in a large cross-sectional study in Norway.MethodsData were drawn from the fourth wave of the Trøndelag Health Study (HUNT4 Hearing, 2017–2019). The hearing threshold was defined as the pure-tone average of 0.5, 1, 2, and 4 kHz in the better ear. The participants were divided into five groups: normal hearing or slight/mild/moderate/severe hearing loss. Subjective self-reported short-term and long-term memory complaints were measured by the nine-item Meta-Memory Questionnaire (MMQ). The sample included 20,092 individuals (11,675 women, mean age 58.3 years) who completed both hearing and MMQ tasks. A multivariate analysis of variance (adjusted for covariates of age, sex, education, and health cofounders) was used to evaluate the association between hearing status and hearing aid use (in the hearing-impaired groups) and long-term and short-term subjective memory complaints.ResultsA multivariate analysis of variance, followed by univariate ANOVA and pairwise comparisons, showed that hearing loss was associated only with more long-term subjective memory complaints and not with short-term subjective memory complaints. In the hearing-impaired groups, the univariate main effect of hearing aid use was only observed for subjective long-term memory complaints and not for subjective short-term memory complaints. Similarly, the univariate interaction of hearing aid use and hearing status was significant for subjective long-term memory complaints and not for subjective short-term memory complaints. Pairwise comparisons, however, revealed no significant differences between hearing loss groups with respect to subjective long-term complaints.ConclusionThis cross-sectional study indicates an association between hearing loss and subjective long-term memory complaints but not with subjective short-term memory complaints. In addition, an interaction between hearing status and hearing aid use for subjective long-term memory complaints was observed in hearing-impaired groups, which calls for future research to examine the effects of hearing aid use on different memory systems.