Accuracy and precision of a custom camera-based system for 2-d and 3-d motion tracking during speech and nonspeech motor tasks

Interarticulator Timing Relations Underlie the Production of Precise and Consistent Vocal Tract Constrictions During Speech

PURPOSE

During speech production, complex patterns of coordinated movements between sets of articulators (e.g., jaw and tongue, jaw and lips) form precise and consistent constrictions at distinct locations along the vocal tract, despite rampant contextual variation. Speech motor control research seeks to uncover basic principles of organization governing interarticulator coordination during constriction formation, assuming many degrees of freedom for controlling articulator movements. This study tested the hypothesis that the motor system reduces degrees of freedom and facilitates coordination by reliably controlling interarticulator timing.

METHOD

Ten talkers produced vowel-consonant-vowel (VCV) sequences, recorded using electromagnetic articulography, with variation in production rate and syllable stress. V was /ɑ/-/ɛ/, and C was alveolar /t/-/d/ or bilabial /p/-/b/. Timing relations between peak velocities of condition-specific sets of articulators were determined during oral closure and release for C: jaw, upper lip, and lower lip for bilabial constrictions and jaw and tongue tip for alveolar constrictions.

RESULTS

During oral closing, the timing of articulator peak velocities was tightly coupled across scalar changes in rate and stress, such that timing variation in one articulator was accompanied by proportional changes in the timing of another articulator. In contrast, the timing of peak velocities was less tightly coupled during subsequent oral opening. The timing of peak velocities was also more reliably differentiated by rate/stress condition during oral closing than opening, indicating that speech articulator movements are temporally coordinated primarily based on the part of movement related to constriction formation, rather than its subsequent release.

CONCLUSION

Findings align with the view that stable interarticulator timing relations underlie the achievement of precise and consistent vocal tract constrictions during speech.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.28791872.

Accuracy of a new photometric jaw tracking system in the frontal plane at different recording distances: An in-vitro study

OBJECTIVES

To evaluate the accuracy of a new photometric jaw tracking system (JTS) in recording linear vertical movements in the frontal plane at different distances.

METHODS

A mandibular plaster cast of a patient was placed on a simulation machine capable of linear movements along two spatial axes. Cyclops JTS (Itaka) was adapted to the plaster cast, while the head frame was attached to the simulation machine. The latter performed five linear movements from 20 to 40 mm in the y-axis; each movement was repeated five times at five different recording distance (380 to 420 mm). The recorded movements were measured and compared with those obtained with a laser Doppler vibrometer (LDV) for accuracy analysis. Data were statistically processed (α = 0.05).

RESULTS

No statistically significant differences were found between Cyclops and LDV measurements on the y- and z-axes (p = 0.5). Changes in linear vertical motion and distance positions did not affect the accuracy, which remained relatively constant with similar trends and values less than 1 % for each parameter variation. The best condition observed was linear vertical movement of 30 mm at 420 mm (0.010 ± 0.023 mm).

CONCLUSIONS

Cyclops has proven to be an accurate JTS in recording linear vertical movements in the frontal plane at different recording distances. For optimal recordings, the scanner should be placed as close as possible to the markers; excessive vertical movements decreased the accuracy. However, this study has limitations and requires in-vivo confirmations.

CLINICAL SIGNIFICANCE

The tested JTS proved accurate in recording linear vertical movements in the frontal plane. However, given the limitations of the study, further investigation under real conditions is needed to support prosthetic and gnathological rehabilitations.

Variables influencing the device-dependent approaches in digitally analysing jaw movement-a systematic review

BACKGROUND

To explore the digitisation of jaw movement trajectories through devices and discuss the physiological factors and device-dependent variables with their subsequent effects on the jaw movement analyses.

METHODS

Based on predefined eligibility criteria, the search was conducted following PRISMA-P 2015 guidelines on MEDLINE, EBSCO Host, Scopus, PubMed, and Web of Science databases in 2022 by 2 reviewers. Articles then underwent Cochrane GRADE approach and JBI critical appraisal for certainty of evidence and bias evaluation.

RESULTS

Thirty articles were included following eligibility screening. Both in vitro experiments (20%) and in vivo (80%) devices ranging from electronic axiography, electromyography, optoelectronic and ultrasonic, oral or extra-oral tracking, photogrammetry, sirognathography, digital pressure sensors, electrognathography, and computerised medical-image tracing were documented. 53.53% of the studies were rated below "moderate" certainty of evidence. Critical appraisal showed 80% case-control investigations failed to address confounding variables while 90% of the included non-randomised experimental studies failed to establish control reference.

CONCLUSION

Mandibular and condylar growth, kinematic dysfunction of the neuromuscular system, shortened dental arches, previous orthodontic treatment, variations in habitual head posture, temporomandibular joint disorders, fricative phonetics, and to a limited extent parafunctional habits and unbalanced occlusal contact were identified confounding variables that shaped jaw movement trajectories but were not highly dependent on age, gender, or diet. Realistic variations in device accuracy were found between 50 and 330 µm across the digital systems with very low interrater reliability for motion tracing from photographs. Forensic and in vitro simulation devices could not accurately recreate variations in jaw motion and muscle contractions.

Biomechanical Comparison of All-Soft Suture Anchor Single-Row vs Double-Row Bridging Construct for Insertional Achilles Tendinopathy

BACKGROUND

Two common operative fixation techniques for insertional Achilles tendinopathy are the use of all-soft suture anchors vs synthetic anchors with a suture bridge. Despite increasing emphasis on early postoperative mobilization, the biomechanical profile of these repairs is not currently known. We hypothesized that the biomechanical profiles of single-row all-soft suture anchor repairs would differ when compared to double-row suture bridge repairs.

METHODS

Achilles tendons were detached from their calcaneal insertions on 6 matched-pair, fresh-frozen cadaver through-knee amputation specimens. Group 1 underwent a single-row repair with all-soft suture anchors. Group 2 was repaired with a double-row bridging suture bridge construct. Achilles-calcaneal displacement was tracked while specimens were cyclically loaded from 10 to 100 N for 2000 cycles and then loaded to failure. Linear mixed models were used to analyze the independent effects of age, body mass index, tendon morphology, repair construct, and footprint size on clinical and ultimate failure loads, Achilles-calcaneal displacement, and mode of failure.

RESULTS

The suture bridge group was independently associated with an approximately 50-N increase in the load to clinical failure (defined as more than 5 mm tendon displacement). There was no difference in ultimate load to failure or tendon/anchor displacement between the 2 groups.

CONCLUSION

This cadaveric study found that a double-row synthetic bridge construct had less displacement during cyclic loading but was not able to carry more load before clinical failure when compared to a single-row suture anchor construct for the operative repair of insertional Achilles tendinopathy.

CLINICAL RELEVANCE

Our data suggest that double-row suture bridge constructs increase the load to clinical failure for operative repairs of insertional Achilles tendinopathy. It must be noted that these loads are well below what occurs during gait and the repair must be protected postoperatively without early mobilization. This study also identified several clinical factors that may help predict repair strength and inform further research.

Assessment of Childhood Apraxia of Speech: A Review/Tutorial of Objective Measurement Techniques

Background With respect to the clinical criteria for diagnosing childhood apraxia of speech (commonly defined as a disorder of speech motor planning and/or programming), research has made important progress in recent years. Three segmental and suprasegmental speech characteristics-error inconsistency, lengthened and disrupted coarticulation, and inappropriate prosody-have gained wide acceptance in the literature for purposes of participant selection. However, little research has sought to empirically test the diagnostic validity of these features. One major obstacle to such empirical study is the fact that none of these features is stated in operationalized terms. Purpose This tutorial provides a structured overview of perceptual, acoustic, and articulatory measurement procedures that have been used or could be used to operationalize and assess these 3 core characteristics. Methodological details are reviewed for each procedure, along with a short overview of research results reported in the literature. Conclusion The 3 types of measurement procedures should be seen as complementary. Some characteristics are better suited to be described at the perceptual level (especially phonemic errors and prosody), others at the acoustic level (especially phonetic distortions, coarticulation, and prosody), and still others at the kinematic level (especially coarticulation, stability, and gestural coordination). The type of data collected determines, to a large extent, the interpretation that can be given regarding the underlying deficit. Comprehensive studies are needed that include more than 1 diagnostic feature and more than 1 type of measurement procedure.

Precision and accuracy of consumer-grade motion tracking system for pedicle screw placement in pediatric spinal fusion surgery

Adolescent idiopathic scoliosis (AIS) is a 3-dimensional spinal deformity involving lateral curvature and axial rotation. Surgical intervention involves insertion of pedicle screws into the spine, requiring accuracies of 1mm and 5° in translation and rotation to prevent neural and vascular complications. While commercial CT-navigation is available, the significant cost, bulk and radiation dose hinders their use in AIS surgery. The objective of this study was to evaluate a commercial-grade Optitrack Prime 13W motion capture cameras to determine if they can achieve adequate accuracy for screw insertion guidance in AIS. Static precision, camera and tracked rigid body configurations, translational and rotational accuracy were investigated. A 1-h camera warm-up time was required to achieve precisions of 0.13mm and 0.10°. A three-camera system configuration with cameras at equal height but staggered depth achieved the best accuracy. A triangular rigid body with 7.9mm markers had superior accuracy. The translational accuracy for motions up to 150mm was 0.25mm while rotational accuracy was 4.9° for rotations in two directions from 0° to 70°. Required translational and rotational accuracies were achieved using this motion capture system as well as being comparable to surgical-grade navigators.