Audiology by Alexandros G. Sfakianakis: 12/24/15

Πέμπτη 24 Δεκεμβρίου 2015

Differences Among Patients That Make Their Tinnitus Worse or Better

Purpose

Our objective was to identify activities that influence tinnitus and to determine if conditional probabilities exist among such variables.

Method

Two hundred fifty-eight patients were asked the following two questions: “When you have your tinnitus, which of the following makes it worse?” and “Which of the following reduces your tinnitus?”

Results

Things that made tinnitus better included noise (31%) and relaxation (15%). Things that made tinnitus worse included being in a quiet place (48%), stress (36%), being in a noisy place (32%), and lack of sleep (27%). Almost 6% of patients suggested coffee/tea and 4% said certain foods made their tinnitus worse. Conditional probabilities indicated that for those whose tinnitus is not worse in quiet, it is usually not reduced by noise. For those whose tinnitus is not worse in noise, it is usually not reduced in quiet.

Conclusion

There are dramatic differences among patients. Such differences need to be considered in planning treatments.

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Frequency Importance Functions in Quiet and Noise for Adults With Cochlear Implants

Purpose

Several studies have been devoted to understanding the frequency information available to adult users of cochlear implants when listening in quiet. The objective of this study was to construct frequency importance functions for a group of adults with cochlear implants and a group of adults with normal hearing both in quiet and in a +10 dB signal-to-noise ratio.

Method

Two groups of adults, 1 with cochlear implants and 1 with normal hearing, were asked to identify nonsense syllables in quiet and in the presence of 6-talker babble while “holes” were systematically created in the speech spectrum. Frequency importance functions were constructed.

Results

Results showed that adults with normal hearing placed greater weight on bands 1, 3, and 4 than on bands 2, 5, and 6, whereas adults with cochlear implants placed equal weight on all bands. The frequency importance functions for each group did not differ between listening in quiet and listening in noise.

Conclusions

Adults with cochlear implants assign perceptual weight toward different frequency bands, though the weight assignment does not differ between quiet and noisy conditions. Generalizing these results to the broader population of adults with implants is constrained by a small sample size.

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Accelerometer-Determined Physical Activity and Mortality in a National Prospective Cohort Study: Considerations by Hearing Sensitivity

Background

Previous work demonstrates that hearing impairment and physical inactivity are associated with premature all-cause mortality. The purpose of this study was to discern whether increased physical activity among those with hearing impairment can produce survival benefits.

Method

Data from the 2003–2006 National Health and Nutrition Examination Survey were used, with follow-up through 2011. Physical activity was objectively measured over 7 days via accelerometry. Hearing sensitivity was objectively measured using a modified Hughson Westlake procedure.

Results

Among the 1,482 participants, 152 died during the follow-up period (10.26%, unweighted); the unweighted median follow-up period was 89 months (interquartile range = 74–98 months). For those with normal hearing and after adjustments, for every 60-min increase in physical activity, adults had a 19% (HR [Hazard Ratio] = 0.81; 95% confidence interval [CI] [0.48–1.35]; p = .40) reduced risk of all-cause mortality; however, this association was not statistically significant. In a similar manner, physical activity was not associated with all-cause mortality among those with mild hearing loss (HR = 0.76; 95% CI [0.51–1.13]; p = .17). However, after adjustments, and for every 60-min increase in physical activity for those with moderate or greater hearing loss, there was a 20% (HR = 0.20; 95% CI [0.67–0.95]; p = .01) reduced risk of all-cause mortality.

Conclusion

Physical activity may help to prolong survival among those with greater hearing impairment.

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Audiometric Thresholds: Stimulus Considerations in Sound Field and Under Earphones

Purpose

This study evaluates a new stimulus, FREquency Specific Hearing assessment (FRESH) noise, to obtain hearing thresholds and reviews the potential pitfalls of using narrow band noise.

Method

Twelve adults with simulated gradually sloping hearing loss and 12 adults with steeply sloping hearing loss participated. Hearing thresholds were measured in sound field and under a supraaural earphone for FRESH noise, warbled tones, and narrowband noise. Pure-tone thresholds were also measured under the supraaural earphone.

Results

FRESH noise thresholds were similar to pure-tone and warbled-tone thresholds regardless of audiometric configuration. For the group with gradually sloping hearing loss, thresholds obtained with narrowband noise were approximately 4 dB better than those obtained with the other test stimuli. For the group with steeply sloping hearing loss, narrowband noise significantly underestimated hearing thresholds—the steeper the hearing loss, the greater the underestimation.

Conclusions

When hearing loss is suspected, FRESH noise is appropriate for accurately determining audiometric thresholds in sound field and under earphones. A wider band, attention-getting stimulus such as narrowband noise can result in thresholds that are inaccurate. Clinical decision making regarding choice of test stimulus is discussed.

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The Relationship Between Hearing Aid Self-Efficacy and Hearing Aid Satisfaction

Purpose

The purpose of this study was to investigate the relationship between self-efficacy for hearing aids (HAs) and satisfaction with HAs in a group of adult HA owners.

Method

Forty-seven adults acquiring HAs (new and experienced owners) completed a demographic questionnaire, the Hearing Handicap Questionnaire (Gatehouse & Noble, 2004), and received an audiometric evaluation prior to HA fitting. Twelve weeks following the completion of the HA fitting, they completed the Measure of Audiologic Rehabilitation Self-Efficacy for Hearing Aids (Smith & West, 2006) and the Satisfaction with Amplification in Daily Life (Cox & Alexander, 1999) questionnaires.

Results

There were no significant differences between experienced and new HA owners in terms of self-efficacy or HA satisfaction. The majority of participants had adequate self-efficacy for basic HA handling and adjustment to HAs. Fewer participants had adequate self-efficacy for aided listening and advanced handling of HAs. HA self-efficacy was related to HA satisfaction in three domains: positive effect and negative features of HAs and service and cost.

Conclusion

Many HA owners do not have adequate self-efficacy in important HA-related domains. Clinical intervention to improve self-efficacy for HAs may help improve HA satisfaction.

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The Effect of Advancing Age on Auditory Middle- and Long-Latency Evoked Potentials Using a Steady-State-Response Approach

Purpose

The purpose of the study was to objectively detect age-specific changes that occur in equivalent auditory steady-state responses (ASSRs), corresponding to transient middle- and long-latency auditory evoked potentials as a function of repetition rate and advancing age.

Method

The study included 48 healthy hearing adults who were equally divided into 3 groups by age: 20–39, 40–59, and 60–79 years. ASSRs were recorded at 7 repetition rates from 40 down to 0.75 Hz, elicited by trains of repeated tone burst stimuli.

Results

Temporal analysis of middle- and long-latency equivalent ASSRs revealed no appreciable changes in the magnitudes of the response across the age groups. Likewise, the spectral analysis revealed that advancing age did not substantially affect the spectral content of the response at each repetition rate. Furthermore, the harmonic sum was not significantly different across the 3 age groups, between the younger adults versus the combined Older Group Sample 1 and Sample 2, and between the two extreme age groups (i.e., 20–39 vs. 60–79) for the middle- and long-latency equivalent ASSRs.

Conclusion

Advancing age has no effect on the long-latency equivalent ASSRs; however, aging does affect the middle-latency equivalent ASSRs when the mean age difference is ≥ 40 years.

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No Association Between Time of Onset of Hearing Loss (Childhood Versus Adulthood) and Self-Reported Hearing Handicap in Adults

Purpose

This study examined the association between time of onset of hearing loss (childhood vs. adulthood) and self-reported hearing handicap in adults.

Methods

This is a population-based cohort study of 2,024 adults (mean = 48 years) with hearing loss (binaural pure-tone average 0.5–4 kHz ≥ 20 dB HL) who completed a hearing handicap questionnaire. In childhood, the same persons (N = 2,024) underwent audiometry in a school investigation (at ages 7, 10, and 13 years), in which 129 were diagnosed with sensorineural hearing loss (binaural pure-tone average 0.5–4 kHz ≥ 20 dB HL), whereas 1,895 had normal hearing thresholds.

Results

Hearing handicap was measured in adulthood as the sum-score of various speech perception and social impairment items (15 items). The sum-score increased with adult hearing threshold level (p n = 129) and the group with adult-onset hearing loss (n = 1,895; p = .882).

Conclusion

Self-reported hearing handicap in adults increased with hearing threshold level. After adjustment for adult hearing threshold level, this cohort study revealed no significant association between time of onset of hearing loss (childhood vs. adulthood) and self-reported hearing handicap.

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Service Learning in Undergraduate Audiology Education

Purpose

The purpose of this study was to incorporate a service learning project in an undergraduate audiology course and evaluate how it affected student learning in the class.

Method

The study involved partnering with a group of students enrolled in a band learning community. Students in the audiology course learned about hearing assessment procedures in class and practiced the procedures on each other in labs. Toward the end of the semester, they assessed the hearing of the band students and provided counseling regarding the importance of hearing protection. Qualitative data were obtained in the form of preflections and final reflection papers completed by the students in the audiology course at the start and conclusion of the semester. Quantitative data included completion of the Community Service Attitudes Scale (CSAS; Shiarella, McCarthy, & Tucker, 2000) prior to and at the conclusion of the course.

Results

Results revealed overwhelmingly positive comments from the students in their final reflections, although there were no significant changes in the pre- and post-administration of the CSAS.

Conclusion

Incorporating service learning projects into undergraduate curricula in speech and hearing has the potential to enhance academic and civic learning while also benefitting the community.

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Factors Influencing Hearing Aid Use in the Classroom: A Pilot Study

Purpose

This pilot study examined factors influencing classroom hearing aid use in school-age children with hearing loss.

Method

The research team visited classrooms of 38 children with mild-to-moderate hearing loss (Grades 1–7) on 2 typical school days, twice per day, to document hearing aid use. In addition, parents reported the number of hours their children used hearing aids at school.

Results

Nearly 24% of children were observed not wearing their hearing aids in the classroom on either observation day. Both grade level and degree of hearing loss appeared to affect hearing aid use. Children in Grades 5–7 and those with milder hearing losses were less likely to wear hearing aids. Overall, parents accurately reported classroom hearing aid use; however, those with children in Grades 5–7 were less accurate than those with children in earlier grades.

Conclusions

These preliminary results suggest that children with milder hearing loss and those in Grades 5–7 are at increased risk for reduced hearing aid use in the classroom. Also, parents of school-age children in these later grades are less accurate reporters of classroom hearing aid use compared to parents of children in earlier grades.

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Influence of Test Condition on Speech Perception With Electric-Acoustic Stimulation

Purpose

The goal of this work was to better understand speech perception for cochlear implant (CI) users with bilateral residual hearing, including consideration of effects related to listening conditions and test measures. Of interest was the role of acoustic hearing for speech perception in a complex background, the role of listening experience for CI-alone conditions, and whether performance with electric-acoustic stimulation (EAS) was improved by a contralateral hearing aid (HA).

Method

Eleven subjects provided data on Consonant-Nucleus-Consonant (CNC; Peterson & Lehiste, 1962) words in quiet, City University of New York (CUNY; Boothroyd, Hanin, & Hnath, 1985) sentences in steady noise, and Bamford-Kowal-Bench (Bench, Kowal, & Bamford, 1979) sentences in multitalker babble. Listening conditions included: CI with a full-frequency map, CI with a truncated-frequency map, EAS, and EAS+HA (EAS plus contralateral HA). Sounds were presented at 0° azimuth.

Results

For CNC words and CUNY sentences, performance was better with the truncated-frequency than the full-frequency map, and performance with EAS was better than for either CI-alone condition. For Bench-Kowal-Bamford sentences, EAS+HA was better than EAS.

Conclusions

As demonstrated previously, performance was better in the EAS condition than either CI-alone condition. Better performance in the truncated-frequency than full-frequency CI-alone condition suggests that listening experience may be important. A contralateral HA improved performance over unilateral EAS under some conditions.

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Mute Button For Tinitus

If you are searching for a mute button for tinitus, you are not alone. Tinnitus is one of the most bothersome auditory conditions that you may develop, and it affects millions of people each year. For many, the condition is characterized by a ringing sound, but the individual may also hear different sounds. These sounds include everything from a whirring sound to buzzing, static, chirping, whistling and more. These sounds may be heard throughout the day, making it difficult for many to go about their daily routine. For some, the condition may persist for years or even for the rest of their lives, and because of this, you may seek out an effective treatment for relief of your symptoms.

Treatment Options for Tinnitus
The unfortunate reality is that there is not an actual mute button for tinitus, but there are some effective treatments that you could try. Each person responds to different treatments in their own way, so it may be necessary for you to experiment to find the one that is most effective for you. For example, some people will use ear drops or take anti-depressants to ease symptoms. Others may meditate in an effort to refocus the brain on something besides the sounds. There is actually a tonal therapy option that some refer to as a mute button for tinitus as well.

A Wonderful Alternative Treatment
Audionotch is an alternative from of mute button or tonal therapy that you can use to treat tinnitus. This is an affordable version that is equally as effective at producing results. The treatment can lessen the intensity of the sound that you hear, and many will notice that their symptoms significantly improve within a few weeks of starting the treatment. This is a non-invasive, non-medical treatment that many people have already successfully used for their treatment.

Whether you have a minor or severe case of tinnitus, you may be interested in learning more about a potential mute button for tinitus. While there is a product that is referred to as this, Audionotch can provide you with similar results at a fraction of the cost. While you may want to improve your hearing condition, you also may not want to empty your wallet doing so. You can learn more about this treatment option for auditory therapy today, and you may consider giving it a try before you take medications or turn to surgery for treatment.

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Normal incidence acoustic insertion loss of perforated plates with bias flow

The transmission of sound at normal incidence through perforated plates with bias flow is investigated experimentally and theoretically over a large parameter space. A specially designed experimental apparatus enabled the measurement of insertion loss with bias flowMach number up to 0.25. A theoretical model for insertion loss was constructed based on inviscid, one-dimensional wave propagation with mean flow through a single contraction/expansion chamber. The mass end correction of the contraction is modified for hole interaction effects and mean flow. Hydrodynamic losses are modeled using a vena contracta coefficient dependent on both perforation geometry and Reynolds number. Losses in acoustic energy that occur in the mixing region downstream of the perforations are modeled as fluctuations in entropy. The proposed model was validated experimentally over a range of plate thickness, porosity, and hole size. The experimental results indicate an increase in insertion loss with increasing frequency, followed by saturation and decline as resonant conditions are established in the perforations. The insertion loss at low frequency increases with increasing Mach number through the perforation. The proposed model captures these trends and its predictions are shown to be more accurate than those of past models.

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Extraction and analysis of body-induced partials of guitar tones

Guitar plucked sounds arise from a rapid input of energy applied to the string coupled to the instrument body at the bridge. For the radiated pressure, this results in quasi-harmonic contributions, reflecting the string modes coupled to the body, as well as some transient and quickly decaying components reflecting the excitation of the body modes of the instrument. In order to evaluate the relevance of this transient body sound, a high resolution analysis-synthesis method is described for the extraction of the body-mode contribution from the radiated pressure measured in the near field of the guitar top plate. This analysis scheme is first tested on synthesized signals. Some body-sound emergence indicators are then proposed and computed over a pool of instruments. The influence of the conditions of excitation on the body-sound emergence is investigated, and the instruments categorized according to these objective descriptors. Results show a larger range of body-sound emergence with variations of the plucking position in hand-made guitars compared to industrial instruments. This suggests that these particular hand-made instruments are more sensitive to variations in the control from the player and hence allow a wider range of timbres with respect to the transient coloration of the body modes.

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On the modeling of visco-thermal dissipations in heterogeneous porous media

Based on a modified equivalent fluid model, the present work proposes a composite model which analytically includes the shape of the inclusions, whether they are porous or not. This model enables to describe the acoustic behavior of a large range of media from perforated plates to arbitrarily shaped porous composites including configurations of porous inclusions in solid matrix or double porosity media. In addition, possible permeability interactions between the substrate material and the inclusions are accounted for.

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Sound source localization in a randomly inhomogeneous medium using matched statistical moment method

This paper investigates the problem of sound source localization from acoustical measurements obtained by an array of microphones. The sound propagation medium is assumed to be randomly inhomogeneous, being modelled by a random function of space. In this case, classical source localization methods (e.g., beamforming, near-field acoustical holography, and time reversal) cannot be used anymore. Therefore, an approach based on the statistical moments of acoustical measurement is proposed to solve the aforementioned problem. In this work, a Karhunen–Loève expansion is used so that the random medium can be represented by a small number of uncorrelated and identically distributed random variables. The statistical characteristics of the measurements in terms of probability density function and statistical moments are also studied. Then, the sound source is localized by minimizing the error of statistical moments between the real measurements obtained from the microphone array and the measurements simulated from an assumed source. Finally, a numerical example is introduced to justify the proposed method. This experiment shows that the random field can be replicated by a very small number of random variables, the statistical moments of measurements guarantee the convergence, and the source location can be accurately estimated using the proposed source localization method.

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Evaluation of road traffic noise abatement by vegetation treatment in a 1:10 urban scale model

A 1:10 scale of a street canyon and courtyard was constructed to evaluate sound propagation when various vegetation treatments including trees, shrubs, vegetated facades, and green roofs were installed in the urban environment. Noise reductions in the street canyon and courtyard were measured for both single and combined vegetation treatments. Vegetated facades mitigated the overall noise level up to 1.6 dBA in the street canyon, and greening facades were effective to reduce low frequency noise levels below 1 kHz. Trees increased the noise level at high frequency bands to some extent in the street canyon, while the noise level over 1 kHz decreased in the courtyard after installing the street trees. This is because tree crowns diffused and reflected high frequency sounds into the street canyon. Green roofs offered significant noise abatement over 1 kHz in the courtyard, while the vegetated facade was effective to reduce noise levels at low frequencies. In terms of the integrated effects of vegetation treatments, a combined vegetation treatment was less effective than the sum of single treatments in the street canyon. The maximum noise reduction observed for all combinations of vegetation treatments provided 3.4 dBA of insertion loss in the courtyard.

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Low-frequency beamforming for a miniaturized aperture three-by-three uniform rectangular array of acoustic vector sensorsa)

This paper proposes a mode domain beamforming method for a 3 × 3 uniform rectangular array of two-dimensional (2D) acoustic vector sensors with inter-sensor spacing much smaller than the wavelengths in the working frequency band. The acoustic modes are extracted from the particle velocity observations in light of the source-sink pictures of the Taylor's series multipoles [Wikswo and Swinney, J. Appl. Phys. 56(11), 3039–3049 (1984)]. Then, similar to other mode domain methods, the modes are synthesized to obtain the desired beam pattern. The proposed method is limited to the cases where five is the maximum order of the modes for pattern synthesis, meaning that the directivity index in the 2D isotropic noise case can reach up to 10.4 dB. The proposed method has been validated by field experiments.

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Structural monitoring of a highway bridge using passive noise recordings from street traffic

Structural damage on bridges presents a hazard to public safety and can lead to fatalities. This article contributes to the development of an alternative monitoring system for civil structures, based on passive measurements of seismic elastic waves. Cross-correlations of traffic noise recorded at geophone receiver pairs were found to be sufficiently stable for comparison and sensitive to velocity changes in the medium. As such velocity variations could be caused by damage, their detection would be valuable in structural health monitoring systems. A method, originally introduced for seismological applications and named Passive Image Interferometry, was used to quantify small velocity fluctuations in the medium and thereby observe structural changes. Evaluation of more than 2 months of continuous geophone recordings at a reinforced concrete bridge yielded velocity variations Δv/v in the range of −1.5% to +2.1%. The observed fluctuations correlate with associated temperaturetime series with a striking resemblance which is remarkable for two completely independent data sets. Using a linear regression approach, a relationship between temperature and velocity variations of on average 0.064% °C⁻¹ can be identified. This value corresponds well to other studies on concrete structures.

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Simulating environmental and psychological acoustic factors of the operating room

In this study, an operating room simulation environment was adapted to include quadraphonic speakers, which were used to recreate a composed clinical soundscape. To assess validity of the composed soundscape, several acoustic parameters of this simulated environment were acquired in the presence of alarms only, background noise only, or both. These parameters were also measured for comparison from size-matched operating rooms at Jackson Memorial Hospital. The parameters examined included sound level, reverberation time, and predictive metrics of speech intelligibility in quiet and noise. It was found that the sound levels and acoustic parameters were comparable between the simulated environment and the actual operating rooms. The impact of the background noise on the perception of medical alarms was then examined, and was found to have little impact on the audibility of the alarms. This study is a first in kind report of a comparison between the environmental and psychological acoustical parameters of a hospital simulation environment and actual operating rooms.

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Acoustic richness modulates the neural networks supporting intelligible speech processing

Publication date: Available online 23 December 2015
Source:Hearing Research
Author(s): Yune-Sang Lee, Nam Eun Min, Arthur Wingfield, Murray Grossman, Jonathan E. Peelle
The information contained in a sensory signal plays a critical role in determining what neural processes are engaged. Here we used interleaved silent steady-state (ISSS) functional magnetic resonance imaging (fMRI) to explore how human listeners cope with different degrees of acoustic richness during auditory sentence comprehension. Twenty-six healthy young adults underwent scanning while hearing sentences that varied in acoustic richness (high vs. low spectral detail) and syntactic complexity (subject-relative vs. object-relative center-embedded clause structures). We manipulated acoustic richness by presenting the stimuli as unprocessed full-spectrum speech, or noise-vocoded with 24 channels. Importantly, although the vocoded sentences were spectrally impoverished, all sentences were highly intelligible. These manipulations allowed us to test how intelligible speech processing was affected by orthogonal linguistic and acoustic demands. Acoustically rich speech showed stronger activation than acoustically less-detailed speech in a bilateral temporoparietal network with more pronounced activity in the right hemisphere. By contrast, listening to sentences with greater syntactic complexity resulted in increased activation of a left-lateralized network including left posterior lateral temporal cortex, left inferior frontal gyrus, and left dorsolateral prefrontal cortex. Significant interactions between acoustic richness and syntactic complexity occurred in left supramarginal gyrus, right superior temporal gyrus, and right inferior frontal gyrus, indicating that the regions recruited for syntactic challenge differed as a function of acoustic properties of the speech. Our findings suggest that the neural systems involved in speech perception are finely tuned to the type of information available, and that reducing the richness of the acoustic signal dramatically alters the brain’s response to spoken language, even when intelligibility is high.

Graphical abstract

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Outer ear canal sound pressure and bone vibration measurement in SSD and CHL patients using a transcutaneous bone conduction instrument

Publication date: Available online 23 December 2015
Source:Hearing Research
Author(s): Mohammad Ghoncheh, Giorgio Lilli, Thomas Lenarz, Hannes Maier
The intraoperative and postoperative objective functional assessment of transcutaneous bone conduction implants is still a challenge. Here we compared intraoperative Laser-Doppler-vibrometry (LDV, Polytec Inc.) to measure vibration of the bone close to the implant to Outer Ear Canal Sound Pressure Level (OEC-SPL) measurements. Twelve single sided deafness (SSD) patients with contralateral intact ossicular chains and eight bilateral conductive hearing loss (CHL) patients were included in the study. SSD patients had a minor average air-bone-gap (ABG) of 0.4 ± 0.4 dB (0.5, 1, 2, 4 kHz mean value (MV) ± standard deviation (SD)) on the contralateral side where a normal transmission between cochlea and the tympanic membrane can be assumed. CHL patients had an impaired middle ear transmission with a mean ABG of 46.0 ± 7.9 dB (MV±SD). Vibration and OEC-SPL responses could reliably be recorded with a minimal signal-to-noise ratio of at least 12 dB.Average OEC-SPL on the contralateral side and intraoperative vibration measurements were strongly correlated in SSD (r²=0.75) and CHL (r²=0.86) patients. The correlation in individual results between OEC-SPL and vibration measurements was weak, indicating some underlying inter-individual variability. The high correlation of average responses showed that OEC-SPL are closely linked to bone vibration, although both cannot be equivalently used for intraoperative testing due to the high variability in individual results. On the other hand, OEC-SPL provides an easy and affordable measurement tool to monitor stability and functionality postoperatively using individual reference measurements.We observed no significant differences (t-test, p<0.05) by comparing results from contralateral OEC-SPL in twelve SSD and eight CHL patients at frequencies between 0.5 and 8 kHz. This implies that the part of the measured sound pressure in the ear canal originating from the cochlea and emitted by the tympanic is not dominant and OEC-SPL is mainly due to vibration of the external ear-canal walls as the only other pathway of BC sound to reach the ear canal. In addition, the transcranial attenuation (contralateral outer ear canal sound pressure divided by ipsilateral) was compared to previous studies measuring vibration by LDV and accelerometer. The trend in the average transcranial attenuation in patients was similar to previous studies measuring the OEC-SPL with less than 5 dB difference.

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A single-ossicle ear: acoustic response and mechanical properties measured in duck

Publication date: Available online 23 December 2015
Source:Hearing Research
Author(s): Pieter G.G. Muyshondt, Joris A.M. Soons, Daniël De Greef, Felipe Pires, Peter Aerts, Joris J.J. Dirckx
To date, the single-ossicle avian middle ear (ME) is poorly understood, despite its striking resemblance to the design of many currently used ossicular replacement prostheses. This study aims to improve comprehension of this system. The acoustic response and the mechanical properties of the mallard middle ear were studied by means of optical interferometry experiments and finite element (FE) simulations. A finite element model was constructed based on μCT data and validated using the experimental results. Stroboscopic holography was used to measure the full-field displacement of the tympanic membrane (TM) under acoustic stimulation, and the transfer function was obtained with laser Doppler vibrometry. A sensitivity analysis concluded that the most influential parameters for ME mechanics are the elasticity of the TM, the extracolumella (the cartilaginous part of the columella) and the annular ligament of the columellar footplate. Estimates for the Young’s modulus of the TM were obtained by iteratively updating the FE model to match experimental data. A considerable inter-individual variability was found for the TM’s elasticity. Comparison of the experimental results and the optimized FE model shows that, similar to the human middle ear, damping needs to be present in the TM to describe the specific spatial and frequency dependent vibrations of the TM. In summary, our results indicate which mechanical parameters are essential to the good functioning of the avian ME and provide a first estimation of their values.

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3D displacement of the middle ear ossicles in the quasi-static pressure regime using new X-ray stereoscopy technique

Publication date: Available online 23 December 2015
Source:Hearing Research
Author(s): Wasil H.M. Salih, Joris J.A.M. Soons, Joris J.J. Dirckx
A novel X-ray stereoscopy technique, using greyscale information obtained from moving markers, was used to study the 3D motion in both gerbil and rabbit middle ear ossicles in the quasi-static pressure regime. The motion can be measured without visually exposing the ossicles. The ossicles showed non-linear behaviour as a function of both pressure and frequency. For instance, about 80% of the maximum umbo displacement occurs at a 1 kPa (peak-to-peak) pressure load, while a limited increase of the amplitude is noticed when the pressure goes to 2 kPa. In rabbit the ratio of stapes to umbo motion amplitude was 0.35 for a pressure of 2 kPa (peak-to-peak) at 0.5 Hz. From two stereoscopic projections of the marker paths, 3D motion of the ossicles could be calculated. This motion is demonstrated on high-resolution computer models in order to visualize ossicular chain behaviour.

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Acoustic richness modulates the neural networks supporting intelligible speech processing

Graphical abstract

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Outer ear canal sound pressure and bone vibration measurement in SSD and CHL patients using a transcutaneous bone conduction instrument

A single-ossicle ear: acoustic response and mechanical properties measured in duck

3D displacement of the middle ear ossicles in the quasi-static pressure regime using new X-ray stereoscopy technique

Acoustic richness modulates the neural networks supporting intelligible speech processing

Graphical abstract

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Outer ear canal sound pressure and bone vibration measurement in SSD and CHL patients using a transcutaneous bone conduction instrument

Publication date: Available online 23 December 2015
Source:Hearing Research
Author(s): Mohammad Ghoncheh, Giorgio Lilli, Thomas Lenarz, Hannes Maier
The intraoperative and postoperative objective functional assessment of transcutaneous bone conduction implants is still a challenge. Here we compared intraoperative Laser-Doppler-vibrometry (LDV, Polytec Inc.) to measure vibration of the bone close to the implant to Outer Ear Canal Sound Pressure Level (OEC-SPL) measurements. Twelve single sided deafness (SSD) patients with contralateral intact ossicular chains and eight bilateral conductive hearing loss (CHL) patients were included in the study. SSD patients had a minor average air-bone-gap (ABG) of 0.4 ± 0.4 dB (0.5, 1, 2, 4 kHz mean value (MV) ± standard deviation (SD)) on the contralateral side where a normal transmission between cochlea and the tympanic membrane can be assumed. CHL patients had an impaired middle ear transmission with a mean ABG of 46.0 ± 7.9 dB (MV±SD). Vibration and OEC-SPL responses could reliably be recorded with a minimal signal-to-noise ratio of at least 12 dB.Average OEC-SPL on the contralateral side and intraoperative vibration measurements were strongly correlated in SSD (r²=0.75) and CHL (r²=0.86) patients. The correlation in individual results between OEC-SPL and vibration measurements was weak, indicating some underlying inter-individual variability. The high correlation of average responses showed that OEC-SPL are closely linked to bone vibration, although both cannot be equivalently used for intraoperative testing due to the high variability in individual results. On the other hand, OEC-SPL provides an easy and affordable measurement tool to monitor stability and functionality postoperatively using individual reference measurements.We observed no significant differences (t-test, p<0.05) by comparing results from contralateral OEC-SPL in twelve SSD and eight CHL patients at frequencies between 0.5 and 8 kHz. This implies that the part of the measured sound pressure in the ear canal originating from the cochlea and emitted by the tympanic is not dominant and OEC-SPL is mainly due to vibration of the external ear-canal walls as the only other pathway of BC sound to reach the ear canal. In addition, the transcranial attenuation (contralateral outer ear canal sound pressure divided by ipsilateral) was compared to previous studies measuring vibration by LDV and accelerometer. The trend in the average transcranial attenuation in patients was similar to previous studies measuring the OEC-SPL with less than 5 dB difference.

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A single-ossicle ear: acoustic response and mechanical properties measured in duck

Publication date: Available online 23 December 2015
Source:Hearing Research
Author(s): Pieter G.G. Muyshondt, Joris A.M. Soons, Daniël De Greef, Felipe Pires, Peter Aerts, Joris J.J. Dirckx
To date, the single-ossicle avian middle ear (ME) is poorly understood, despite its striking resemblance to the design of many currently used ossicular replacement prostheses. This study aims to improve comprehension of this system. The acoustic response and the mechanical properties of the mallard middle ear were studied by means of optical interferometry experiments and finite element (FE) simulations. A finite element model was constructed based on μCT data and validated using the experimental results. Stroboscopic holography was used to measure the full-field displacement of the tympanic membrane (TM) under acoustic stimulation, and the transfer function was obtained with laser Doppler vibrometry. A sensitivity analysis concluded that the most influential parameters for ME mechanics are the elasticity of the TM, the extracolumella (the cartilaginous part of the columella) and the annular ligament of the columellar footplate. Estimates for the Young’s modulus of the TM were obtained by iteratively updating the FE model to match experimental data. A considerable inter-individual variability was found for the TM’s elasticity. Comparison of the experimental results and the optimized FE model shows that, similar to the human middle ear, damping needs to be present in the TM to describe the specific spatial and frequency dependent vibrations of the TM. In summary, our results indicate which mechanical parameters are essential to the good functioning of the avian ME and provide a first estimation of their values.

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3D displacement of the middle ear ossicles in the quasi-static pressure regime using new X-ray stereoscopy technique

Publication date: Available online 23 December 2015
Source:Hearing Research
Author(s): Wasil H.M. Salih, Joris J.A.M. Soons, Joris J.J. Dirckx
A novel X-ray stereoscopy technique, using greyscale information obtained from moving markers, was used to study the 3D motion in both gerbil and rabbit middle ear ossicles in the quasi-static pressure regime. The motion can be measured without visually exposing the ossicles. The ossicles showed non-linear behaviour as a function of both pressure and frequency. For instance, about 80% of the maximum umbo displacement occurs at a 1 kPa (peak-to-peak) pressure load, while a limited increase of the amplitude is noticed when the pressure goes to 2 kPa. In rabbit the ratio of stapes to umbo motion amplitude was 0.35 for a pressure of 2 kPa (peak-to-peak) at 0.5 Hz. From two stereoscopic projections of the marker paths, 3D motion of the ossicles could be calculated. This motion is demonstrated on high-resolution computer models in order to visualize ossicular chain behaviour.

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[Long-term efficacy of triple semicircular canal occlusion in the treatment of intractable Meniere's disease].

[Long-term efficacy of triple semicircular canal occlusion in the treatment of intractable Meniere's disease].

Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi. 2015 Sep;50(9):733-7

Authors: Zhang D, Fan Z, Han Y, Li Y, Wang H

Abstract
OBJECTIVE: To explore the long-term efficacy and safety of triple semicircular canal occlusion (TSCO) in the treatment of intractable Meniere's disease (MD) so as to provide an alternative surgical procedure for treating this disorder.
METHODS: Data from Forty-nine patients, who were referred to our hospital and diagnosed with unilateral MD strictly meeting the criteria issued by Chinese Academy of Otolaryngology-Head and Neck Surgery Committee (2006) from Dec. 2010 to Jul. 2012, were retrospectively analyzed in this work. Forty-nine patients, in whom the standardized conservative treatment was given at least one year and frequent vertigo still occurred, received TSCO. Vertigo control and auditory function were measured. Pure tone audiometry, caloric test, and cervical vestibular evoked myogenic potential (cVEMP) were performed for evaluation of audiological and vestibular function. Magnetic resonance hydrograph of inner ear was performed in patients received TSCO after 2 years for the observation of morphology of membranous labyrinth. Postoperative follow-up period was more than 2 years.
RESULTS: According to the preoperative staging of hearing, among these 49 patients, there were 2 cases in stage II (with an average hearing threshold of 25-40 dBHL), 40 in stage III (41-70 dBHL) and 7 in stage IV (over 70 dBHL). Vertigo was controlled effectively in all 49 cases in two-year follow-up, of which 40 cases (81.6%) were completely controlled and 9 cases (18.4%) were substantially controlled after surgery. The rate of hearing preservation was 69.4% and the rate of hearing loss was 30.6%. Post-operatively, all patients suffered from temporary vertigo and balance disorders. Vertigo was disappeared in all patients within 3-5 days, while averagely recovered after 13.5 days. Two years afer treatment, loss of semicircular canal function by caloric test was found in the operation side of all patients and no change in cVEMP test was noted. All patients had no facial paralysis, cerebrospinal fluid leakage, and other complications. Magnetic resonance hydrograph of inner ear showed that endolymph fluid in the position of plugging had no water after 2-years of TSCO.
CONCLUSIONS: TSCO, which can reduce vertiginous symptoms effectively in patients with intractable MD in long-term follow-up, represents an effective and safe therapy for this disorder. TSCO is expected to be used as an alternative procedure for the treatment of MD in selected patients suffering from severe hearing loss or recurrence after endolymphatic sac surgery.

PMID: 26696345 [PubMed - in process]

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[Long-term efficacy of triple semicircular canal occlusion in the treatment of intractable Meniere's disease].

[Long-term efficacy of triple semicircular canal occlusion in the treatment of intractable Meniere's disease].

Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi. 2015 Sep;50(9):733-7

Authors: Zhang D, Fan Z, Han Y, Li Y, Wang H

PMID: 26696345 [PubMed - in process]

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Acoustic richness modulates the neural networks supporting intelligible speech processing

Graphical abstract

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Outer ear canal sound pressure and bone vibration measurement in SSD and CHL patients using a transcutaneous bone conduction instrument

A single-ossicle ear: acoustic response and mechanical properties measured in duck

3D displacement of the middle ear ossicles in the quasi-static pressure regime using new X-ray stereoscopy technique

Acoustic richness modulates the neural networks supporting intelligible speech processing

Graphical abstract

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Outer ear canal sound pressure and bone vibration measurement in SSD and CHL patients using a transcutaneous bone conduction instrument

A single-ossicle ear: acoustic response and mechanical properties measured in duck

3D displacement of the middle ear ossicles in the quasi-static pressure regime using new X-ray stereoscopy technique

The effect of footwear and footfall pattern on running stride interval long-range correlations and distributional variability

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Joel T. Fuller, Avelino Amado, Richard E.A van Emmerik, Joseph Hamill, Jonathan D. Buckley, Margarita D. Tsiros, Dominic Thewlis
The presence of long-range correlations (self-similarity) in the stride-to-stride fluctuations in running stride interval has been used as an indicator of a healthy adaptable system. Changes to footfall patterns when running with minimalist shoes could cause a less adaptable running gait. The purpose of this study was to investigate stride interval variability and the degree of self-similarity of stride interval in runners wearing minimalist and conventional footwear. Twenty-six trained habitual rearfoot footfall runners, unaccustomed to running in minimalist footwear, performed 6-min sub-maximal treadmill running bouts at 11, 13 and 15 km·h⁻¹ in minimalist and conventional shoes. Force sensitive resistors were placed in the shoes to quantify stride interval (time between successive foot contacts). Footfall position, stride interval mean and coefficient of variation (CV), were used to assess performance as a function of shoe type. Long-range correlations of stride interval were assessed using detrended fluctuation analysis (α). Mean stride interval was 1-1.3% shorter (P=0.02) and 27% of runners adopted a midfoot footfall (MFF) in the minimalist shoe. There was a significant shoe effect on α and shoe*speed*footfall interaction effect on CV (P<0.05). Runners that adopted a MFF in minimalist shoes, displayed reduced long-range correlations (P<0.05) and CV (P<0.06) in their running stride interval at the 15 km·h⁻¹ speed. The reduced variability and self-similarity observed for runners that changed to a MFF in the minimalist shoe may be suggestive of a system that is less flexible and more prone to injury.

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Normal aging increases postural preparation errors: Evidence from a two-choice response task with balance constraints

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Julius Verrel, Nina Lisofsky, Simone Kühn, Ulman Lindenberger
Correlational studies indicate an association between age-related decline in balance and cognitive control, but these functions are rarely addressed within a single task. In this study, we investigate adult age differences in a two-choice response task with balance constraints under three levels of response conflict. Sixteen healthy young (20–30years) and 16 healthy older adult participants (59–74years) were cued symbolically (letter L vs. R) to lift either the left or the right foot from the floor in a standing position. Response conflict was manipulated by task-irrelevant visual stimuli showing congruent, incongruent, or no foot lift movement. Preparatory weight shifts (PWS) and foot lift movements were recorded using force plates and optical motion capture. Older adults showed longer response times (foot lift) and more PWS errors than younger adults. Incongruent distractors interfered with performance (greater response time and PWS errors), but this compatibility effect did not reliably differ between age groups. Response time effects of age and compatibility were strongly reduced or absent in trials without PWS errors, and for the onset of the first (erroneous) PWS in trials with preparation error. In addition, in older adults only, compatibility effects in the foot lift task correlated significantly with compatibility effects in the Flanker task. The present results strongly suggest that adult age differences in response latencies in a task with balance constraints are related to age-associated increases in postural preparation errors rather than being an epiphenomenon of general slowing.

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Strategies for equilibrium maintenance during single leg standing on a wobble board

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Priscila de Brito Silva, Natalie Mrachacz-Kersting, Anderson Souza Oliveira, Uffe Laessoe, Uwe Gustav Kersting
The aim of this study was to identify and compare movement strategies used to maintain balance while single leg standing on either a firm surface (FS) or on a wobble board (WB). In 17 healthy men, retroreflective markers were positioned on the xiphoid process and nondominant lateral malleolus to calculate trunk and contralateral-leg excursion (EXC) and velocity (VEL), and center of pressure (CoP) EXC and VEL during FS on a force platform. From the WB test, standing time (WBTIME) was determined and the board's angular EXC and VEL were calculated from four markers on the WB as surrogate measures for CoP dynamics. Electromyographic average rectified values (ARV) from eight leg and thigh muscles of the supporting limb were calculated for both tasks. WB ARV amplitudes were normalized with respect to the value of FS ARV and presented significantly higher peroneus longus and biceps femoris activity (p<0.05). WB standing time was correlated to trunk sagittal plane velocity (r=−0.73 at p=0.016) and excursion (r=−0.67 at p=0.03). CoP and WB angular movement measures were weakly and not significantly correlated between tasks. This lack of correlation indicates that WB balance maintenance requires movement beyond the ankle strategy as described for the FS task. WB standing likely demands different biomechanical and neuromuscular control strategies, which has immediate implications for the significance of WB tests in contrast to FS balance tests. Differences in control strategies will also have implications for the understanding of mechanisms for rehabilitation training using such devices.

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The effect of footwear and footfall pattern on running stride interval long-range correlations and distributional variability

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Joel T. Fuller, Avelino Amado, Richard E.A van Emmerik, Joseph Hamill, Jonathan D. Buckley, Margarita D. Tsiros, Dominic Thewlis
The presence of long-range correlations (self-similarity) in the stride-to-stride fluctuations in running stride interval has been used as an indicator of a healthy adaptable system. Changes to footfall patterns when running with minimalist shoes could cause a less adaptable running gait. The purpose of this study was to investigate stride interval variability and the degree of self-similarity of stride interval in runners wearing minimalist and conventional footwear. Twenty-six trained habitual rearfoot footfall runners, unaccustomed to running in minimalist footwear, performed 6-min sub-maximal treadmill running bouts at 11, 13 and 15 km·h⁻¹ in minimalist and conventional shoes. Force sensitive resistors were placed in the shoes to quantify stride interval (time between successive foot contacts). Footfall position, stride interval mean and coefficient of variation (CV), were used to assess performance as a function of shoe type. Long-range correlations of stride interval were assessed using detrended fluctuation analysis (α). Mean stride interval was 1-1.3% shorter (P=0.02) and 27% of runners adopted a midfoot footfall (MFF) in the minimalist shoe. There was a significant shoe effect on α and shoe*speed*footfall interaction effect on CV (P<0.05). Runners that adopted a MFF in minimalist shoes, displayed reduced long-range correlations (P<0.05) and CV (P<0.06) in their running stride interval at the 15 km·h⁻¹ speed. The reduced variability and self-similarity observed for runners that changed to a MFF in the minimalist shoe may be suggestive of a system that is less flexible and more prone to injury.

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Normal aging increases postural preparation errors: Evidence from a two-choice response task with balance constraints

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Julius Verrel, Nina Lisofsky, Simone Kühn, Ulman Lindenberger
Correlational studies indicate an association between age-related decline in balance and cognitive control, but these functions are rarely addressed within a single task. In this study, we investigate adult age differences in a two-choice response task with balance constraints under three levels of response conflict. Sixteen healthy young (20–30years) and 16 healthy older adult participants (59–74years) were cued symbolically (letter L vs. R) to lift either the left or the right foot from the floor in a standing position. Response conflict was manipulated by task-irrelevant visual stimuli showing congruent, incongruent, or no foot lift movement. Preparatory weight shifts (PWS) and foot lift movements were recorded using force plates and optical motion capture. Older adults showed longer response times (foot lift) and more PWS errors than younger adults. Incongruent distractors interfered with performance (greater response time and PWS errors), but this compatibility effect did not reliably differ between age groups. Response time effects of age and compatibility were strongly reduced or absent in trials without PWS errors, and for the onset of the first (erroneous) PWS in trials with preparation error. In addition, in older adults only, compatibility effects in the foot lift task correlated significantly with compatibility effects in the Flanker task. The present results strongly suggest that adult age differences in response latencies in a task with balance constraints are related to age-associated increases in postural preparation errors rather than being an epiphenomenon of general slowing.

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Strategies for equilibrium maintenance during single leg standing on a wobble board

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Priscila de Brito Silva, Natalie Mrachacz-Kersting, Anderson Souza Oliveira, Uffe Laessoe, Uwe Gustav Kersting
The aim of this study was to identify and compare movement strategies used to maintain balance while single leg standing on either a firm surface (FS) or on a wobble board (WB). In 17 healthy men, retroreflective markers were positioned on the xiphoid process and nondominant lateral malleolus to calculate trunk and contralateral-leg excursion (EXC) and velocity (VEL), and center of pressure (CoP) EXC and VEL during FS on a force platform. From the WB test, standing time (WBTIME) was determined and the board's angular EXC and VEL were calculated from four markers on the WB as surrogate measures for CoP dynamics. Electromyographic average rectified values (ARV) from eight leg and thigh muscles of the supporting limb were calculated for both tasks. WB ARV amplitudes were normalized with respect to the value of FS ARV and presented significantly higher peroneus longus and biceps femoris activity (p<0.05). WB standing time was correlated to trunk sagittal plane velocity (r=−0.73 at p=0.016) and excursion (r=−0.67 at p=0.03). CoP and WB angular movement measures were weakly and not significantly correlated between tasks. This lack of correlation indicates that WB balance maintenance requires movement beyond the ankle strategy as described for the FS task. WB standing likely demands different biomechanical and neuromuscular control strategies, which has immediate implications for the significance of WB tests in contrast to FS balance tests. Differences in control strategies will also have implications for the understanding of mechanisms for rehabilitation training using such devices.

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The effect of footwear and footfall pattern on running stride interval long-range correlations and distributional variability

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Joel T. Fuller, Avelino Amado, Richard E.A van Emmerik, Joseph Hamill, Jonathan D. Buckley, Margarita D. Tsiros, Dominic Thewlis
The presence of long-range correlations (self-similarity) in the stride-to-stride fluctuations in running stride interval has been used as an indicator of a healthy adaptable system. Changes to footfall patterns when running with minimalist shoes could cause a less adaptable running gait. The purpose of this study was to investigate stride interval variability and the degree of self-similarity of stride interval in runners wearing minimalist and conventional footwear. Twenty-six trained habitual rearfoot footfall runners, unaccustomed to running in minimalist footwear, performed 6-min sub-maximal treadmill running bouts at 11, 13 and 15 km·h⁻¹ in minimalist and conventional shoes. Force sensitive resistors were placed in the shoes to quantify stride interval (time between successive foot contacts). Footfall position, stride interval mean and coefficient of variation (CV), were used to assess performance as a function of shoe type. Long-range correlations of stride interval were assessed using detrended fluctuation analysis (α). Mean stride interval was 1-1.3% shorter (P=0.02) and 27% of runners adopted a midfoot footfall (MFF) in the minimalist shoe. There was a significant shoe effect on α and shoe*speed*footfall interaction effect on CV (P<0.05). Runners that adopted a MFF in minimalist shoes, displayed reduced long-range correlations (P<0.05) and CV (P<0.06) in their running stride interval at the 15 km·h⁻¹ speed. The reduced variability and self-similarity observed for runners that changed to a MFF in the minimalist shoe may be suggestive of a system that is less flexible and more prone to injury.

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Normal aging increases postural preparation errors: Evidence from a two-choice response task with balance constraints

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Julius Verrel, Nina Lisofsky, Simone Kühn, Ulman Lindenberger
Correlational studies indicate an association between age-related decline in balance and cognitive control, but these functions are rarely addressed within a single task. In this study, we investigate adult age differences in a two-choice response task with balance constraints under three levels of response conflict. Sixteen healthy young (20–30years) and 16 healthy older adult participants (59–74years) were cued symbolically (letter L vs. R) to lift either the left or the right foot from the floor in a standing position. Response conflict was manipulated by task-irrelevant visual stimuli showing congruent, incongruent, or no foot lift movement. Preparatory weight shifts (PWS) and foot lift movements were recorded using force plates and optical motion capture. Older adults showed longer response times (foot lift) and more PWS errors than younger adults. Incongruent distractors interfered with performance (greater response time and PWS errors), but this compatibility effect did not reliably differ between age groups. Response time effects of age and compatibility were strongly reduced or absent in trials without PWS errors, and for the onset of the first (erroneous) PWS in trials with preparation error. In addition, in older adults only, compatibility effects in the foot lift task correlated significantly with compatibility effects in the Flanker task. The present results strongly suggest that adult age differences in response latencies in a task with balance constraints are related to age-associated increases in postural preparation errors rather than being an epiphenomenon of general slowing.

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Strategies for equilibrium maintenance during single leg standing on a wobble board

Publication date: February 2016
Source:Gait & Posture, Volume 44
Author(s): Priscila de Brito Silva, Natalie Mrachacz-Kersting, Anderson Souza Oliveira, Uffe Laessoe, Uwe Gustav Kersting
The aim of this study was to identify and compare movement strategies used to maintain balance while single leg standing on either a firm surface (FS) or on a wobble board (WB). In 17 healthy men, retroreflective markers were positioned on the xiphoid process and nondominant lateral malleolus to calculate trunk and contralateral-leg excursion (EXC) and velocity (VEL), and center of pressure (CoP) EXC and VEL during FS on a force platform. From the WB test, standing time (WBTIME) was determined and the board's angular EXC and VEL were calculated from four markers on the WB as surrogate measures for CoP dynamics. Electromyographic average rectified values (ARV) from eight leg and thigh muscles of the supporting limb were calculated for both tasks. WB ARV amplitudes were normalized with respect to the value of FS ARV and presented significantly higher peroneus longus and biceps femoris activity (p<0.05). WB standing time was correlated to trunk sagittal plane velocity (r=−0.73 at p=0.016) and excursion (r=−0.67 at p=0.03). CoP and WB angular movement measures were weakly and not significantly correlated between tasks. This lack of correlation indicates that WB balance maintenance requires movement beyond the ankle strategy as described for the FS task. WB standing likely demands different biomechanical and neuromuscular control strategies, which has immediate implications for the significance of WB tests in contrast to FS balance tests. Differences in control strategies will also have implications for the understanding of mechanisms for rehabilitation training using such devices.

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Πληροφορίες

Πέμπτη 24 Δεκεμβρίου 2015

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Graphical abstract