Reference equivalent threshold sound pressure levels for the Wireless Automated Hearing Test System.

This paper presents reference equivalent threshold sound pressure levels (RETSPLs) for the Wireless Automated Hearing Test System (WAHTS), a recently commercialized device developed for use as a boothless audiometer. Two initial studies were conducted following the ISO 389-9 standard [ISO 389-9 (2009). "Acoustics-Reference zero for the calibration of audiometric equipment. Part 9: Preferred test conditions for the determinations of reference hearing threshold levels" (International Organization for Standardization, Geneva)]. Although the standard recruitment criteria are intended to yield otologically normal test subjects, the recruited populations appeared to have slightly elevated thresholds [5-10 dB hearing level (HL)]. Comparison of WAHTS thresholds to other clinical audiometric equipment revealed bias errors that were consistent with the elevated thresholds of the RETSPL populations. As the objective of RETSPLs is to ensure consistent thresholds regardless of the equipment, this paper presents the RETSPLs initially obtained following ISO 389-9:2009 and suggested correction to account for the elevated HLs of the originally recruited populations. Two additional independent studies demonstrate the validity of these corrected thresholds.

TabSINT: open-source mobile software for distributed studies of hearing.

Objective: The recent emphasis on outcomes-based medical research has motivated a need for technology that allows researchers and clinicians to reach a larger and more diverse subject population for recruitment and testing.Design: This article reports on open-source mobile software (TabSINT) that enables researchers to administer customised hearing tests and questionnaires on tablets located across multiple sites. Researchers create and modify test protocols using text-based templates and deploy it to the tablets via a cloud-based repository or USB-computer connection. Results are exported locally to the tablet SD card and can also be automatically posted to a cloud-based database.Results: Between 2014 and 2019, TabSINT collected 25,000+ test results using more than 200+ unique test protocols for researchers located worldwide.Conclusions:TabSINT is a powerful software system with the potential to greatly enhance research across multiple disciplines by enabling access to subject cohorts in remote and disparate locations. Released open-source, this software is available to researchers across the world to use and adapt to their specific needs. Researchers with engineering resources can contribute to the repository to extend the capability and robustness of this software.

An introduction to tribology.

Tribology is the study of friction, wear, lubrication mechanisms, and their interrelationships. Biotribiology focuses on understanding diarthrodial joints and has been a branch of tribology since 1973. Since then, biotribology has played a prominent role in the evaluation and development of joint prostheses, contributing to reduced wear and increased longevity. Total joint replacements are now common for arthritic patients and are also used in treating a variety of other orthopaedic conditions. For this reason, a complete understanding of the joint lubrication and microstructure that exists in nature is crucial. A subfield of biotribology, biomimetic tribology, has been formed with this goal in mind. This review covers the basic concepts of tribology, provides a brief historical perspective on joint prostheses, and presents the application of tribology in understanding diarthrodial and prosthetic joints.

Quantifying spasticity in a clinical setting.

We describe a technique specifically designed for use in a clinical setting to quantify the spastic reflex response. Spasticity, which manifests as a hyperactive stretch reflex response, is the major component of cerebral palsy (CP) that interferes with normal function. Clinically, a patient's spasticity is monitored and subjectively graded by an examiner while moving the joint throughout its range of motion. Grading of the abnormal resistance is classified by clinical scales. The subjective clinical scales, however, tend to have poor inter-rater reliability and often poor correlation with functional improvements. Although objective measures of spasticity exist, their use has been limited to research laboratories, they have not been applied to the CP population, and their usefulness is determined by their correlation with subjective clinical measures. We describe a technique to quantify spasticity in a clinical setting. This technique, termed CATCH (Computer Assisted Technique to Characterize Hypertonia) integrates measurement of joint kinematics and muscle electromyography to quantify the spastic reflex response in CP. Three clinical cases are presented. These preliminary examples from the clinic suggest that this technique provides an improved method to monitor spasticity.

Effect of augmented plantarflexion power on preferred walking speed and economy in young and older adults.

With age, loss of skeletal muscle mass (sarcopenia) results in decreased muscle strength and power. Decreased strength and power, in turn, are closely linked with declines in physical function. Preferred walking speed, a marker of physical function, is slower in older adults compared to young adults. Research suggests that older adults may walk slower as a consequence of decreased plantarflexor power at push-off. In this study, we hypothesized that providing additional plantarflexion (PF) power during push-off would (1) increase preferred walking speed, and (2) reduce metabolic cost of transport (MCOT), in young and older adults. PF power was augmented using powered ankle-foot orthoses (PAFOs). The PAFOs, which use pneumatic actuators to provide an additional PF moment, were based on a design by Ferris et al. [Ferris DP, Czerniecki JM, Hannaford B. An ankle-foot orthosis powered by artificial pneumatic muscles. J Appl Biomech 2005;21:189-97.]. Nine young (23.3+/-1.6 years) and seven older (74.6+/-6.6 years) adults participated. For the young adults, eight out of nine increased their preferred walking speed when push-off power was augmented (1.18+/-0.16 to 1.25+/-0.16m/s, p=0.03). A similar, but non-significant, trend in preferred walking speed was observed for the older adults. With augmented push-off power, MCOT for young adults decreased from 0.395+/-0.057 to 0.343+/-0.047 (p=0.008); indicating that the neuromuscular system was able to adapt to use external energy to reduce metabolic cost. Only three older adults were tested but MCOT values showed a similar trend. Augmenting PF power increases gait speed and reduces MCOT in young adults. Older adults may need a longer period to take advantage of additional push-off power.

Ability of static and statistical mechanics posturographic measures to distinguish between age and fall risk.

Traditional posturographic analysis and four statistical mechanics techniques were applied to center-of-pressure (COP) trajectories of young, older "low-fall-risk" and older "high-fall-risk" individuals. Low-fall-risk older adults were active 3 days per week in a cardiac rehabilitation program, while high-fall-risk older adults were diagnosed with perilymph fistula. Subjects diagnosed with perilymph fistula must have experienced two of the following vestibular findings: constant disequilibrium, positional vertigo and/or a positive fistula test. Non-parametric statistical tests were used to determine whether the posturographic measures could detect differences between the young and older "low-fall-risk" groups (age comparison) and between the older "low-" and "high-risk" groups (risk of falling comparison). The statistical mechanics techniques were more sensitive than the traditional measures: detecting significant differences between the young and older "low-risk" groups, while none of the traditional measures were significantly different. In addition, interpretation of the statistical mechanics techniques may offer more insight into the nature of the process controlling the COP trajectories. However, the methods offered slightly different explanations. For instance, the Hurst rescaled range analysis suggests that the movement of the COP is governed solely by anti-persistent behavior, whereas the stabilogram diffusion analysis suggests a short-term persistence balanced by a long-term anti-persistence. These discrepancies highlight the need for a model that incorporates the biological systems responsible for maintaining balance and experimental methods to directly quantify their status and roles. Until such a model exists, however, the statistical mechanics techniques appear to have some advantages over traditional posturographic measures for studying balance control.