The Compartmental Tongue.

PURPOSE: Tongue anatomy and function is widely described as consisting of four extrinsic muscles to control position and four intrinsic muscles to control shape. This myoarchitecture cannot, however, explain independent tongue body and blade movement nor accurately model the subtlety of observed lingual shapes. This study presents the case for a finer neuromuscular structure and functional description. METHOD: Using the theoretical framework of the partitioning hypothesis, evidence for neuromuscular compartments of each of the lingual muscles was discerned by reviewing studies of lingual anatomy, hypoglossal nerve staining, hypoglossal motoneuron axon tracing, muscle fiber type distribution, and electromyography. Muscle fibers of the visible human female were manually traced to produce a three-dimensional atlas of muscular compartments. A kinematic study was undertaken to determine the degree of independent movement between different parts of the tongue. A simple biomechanical model was used to demonstrate how synergistic groups of compartments can control sectors of the tongue. RESULTS: Results indicated as many as 10 compartments of genioglossus, two each of superior and inferior longitudinal, eight of styloglossus, three of hyoglossus, and six each of transversus and verticalis, while palatoglossus may not have a significant role in tongue function. Kinematic analysis indicated independent control of five sectors of the tongue body, and biomechanical modeling demonstrated how this control may be achieved. CONCLUSION: Evidence is presented for a lingual structure based on neuromuscular compartments, which work together to position and shape sectors of the tongue and independently control tongue body and blade.

Automated assessment of hyoid movement during normal swallow using ultrasound.

BACKGROUND: The potential for using ultrasound by speech and language therapists (SLTs) as an adjunct clinical tool to assess swallowing function has received increased attention during the COVID-19 pandemic, with a recent review highlighting the need for further research on normative data, objective measurement, elicitation protocol and training. The dynamic movement of the hyoid, visible in ultrasound, is crucial in facilitating bolus transition and protection of the airway during a swallow and has shown promise as a biomarker of swallowing function. AIMS: To examine the kinematics of the hyoid during a swallow using ultrasound imaging and to relate the patterns to the different stages of a normal swallow. To evaluate the accuracy and robustness of two different automatic hyoid tracking methods relative to manual hyoid position estimation. METHODS & PROCEDURES: Ultrasound data recorded from 15 healthy participants swallowing a 10 ml water bolus delivered by cup or spoon were analysed. The movement of the hyoid was tracked using manually marked frame-to-frame positions, automated hyoid shadow tracking and deep neural net (DNN) tracking. Hyoid displacement along the horizontal image axis (HxD) was charted throughout a swallow, and the maximum horizontal displacement (HxD max) and maximum hyoid velocity (HxV max) along the same axis were automatically calculated. OUTCOMES & RESULTS: The HxD and HxV of 10 ml swallows are similar to values reported in the literature. The trajectory of the hyoid movement and its location at significant swallow event time points showed increased hyoid displacement towards the peak of the swallow. Using an interclass correlation coefficient, HxD max and HxV max values derived from the DNN tracker and shadow tracker are shown to be in high agreement and moderate agreement, respectively, when compared with values derived from manual tracking. CONCLUSIONS & IMPLICATIONS: The similarity of the hyoid tracking results using ultrasound to previous reports based on different instrumental tools supports the possibility of using hyoid movement as a measure of swallowing function in ultrasound. The use of machine learning to automatically track the hyoid movement potentially provides a reliable and efficient way to quantify swallowing function. These findings contribute towards improving the clinical utility of ultrasound as a swallowing assessment tool. Further research on both normative and clinical populations is needed to validate hyoid movement metrics as a means of differentiating normal and abnormal swallows and to verify the reliability of automatic tracking. WHAT THIS PAPER ADDS: What is already known on this subject There is growing interest in the use of ultrasound as an adjunct tool for assessing swallowing function. However, there is currently insufficient knowledge about the patterning and timing of lingual and hyoid movement in a typical swallow. We know that movement of the hyoid plays an essential role in bolus transition and airway protection. However, manual tracking of hyoid movement is time-consuming and restricts the extent of large-scale normative studies. What this study adds We show that hyoid movement can be tracked automatically, providing measurable continuous positional data. Measurements derived from this objective data are comparable with similar measures previously reported using videofluoroscopy and of the two automatic trackers assessed, the DNN approach demonstrates better robustness and higher agreement with manually derived measures. Using this kinematic data, hyoid movement can be related to different stages of swallowing. Clinical implications of this study This study contributes towards our understanding of the kinematics of a typical swallow by evaluating an automated hyoid tracking method, paving the way for future studies of typical and disordered swallow. The challenges of image acquisition highlight issues to be considered when establishing clinical protocols. The application of machine learning enhances the utility of ultrasound swallowing assessment by reducing the labour required and permitting a wider range of hyoid measurements. Further research in normative and clinical populations is facilitated by automatic data extraction allowing the validity of prospective hyoid measures in differentiating different types of swallows to be rigorously assessed.

Beyond the Edge: Markerless Pose Estimation of Speech Articulators from Ultrasound and Camera Images Using DeepLabCut.

Automatic feature extraction from images of speech articulators is currently achieved by detecting edges. Here, we investigate the use of pose estimation deep neural nets with transfer learning to perform markerless estimation of speech articulator keypoints using only a few hundred hand-labelled images as training input. Midsagittal ultrasound images of the tongue, jaw, and hyoid and camera images of the lips were hand-labelled with keypoints, trained using DeepLabCut and evaluated on unseen speakers and systems. Tongue surface contours interpolated from estimated and hand-labelled keypoints produced an average mean sum of distances (MSD) of 0.93, s.d. 0.46 mm, compared with 0.96, s.d. 0.39 mm, for two human labellers, and 2.3, s.d. 1.5 mm, for the best performing edge detection algorithm. A pilot set of simultaneous electromagnetic articulography (EMA) and ultrasound recordings demonstrated partial correlation among three physical sensor positions and the corresponding estimated keypoints and requires further investigation. The accuracy of the estimating lip aperture from a camera video was high, with a mean MSD of 0.70, s.d. 0.56 mm compared with 0.57, s.d. 0.48 mm for two human labellers. DeepLabCut was found to be a fast, accurate and fully automatic method of providing unique kinematic data for tongue, hyoid, jaw, and lips.

The Impact of Real-Time Articulatory Information on Phonetic Transcription: Ultrasound-Aided Transcription in Cleft Lip and Palate Speech.

OBJECTIVE: This study investigated whether adding an additional modality, namely ultrasound tongue imaging (UTI), to perception-based phonetic transcription impacted on the identification of compensatory articulations and on interrater reliability. PATIENTS AND METHODS: Thirty-nine English-speaking children aged 3-12 years with cleft lip and palate (CLP) were recorded producing repetitions of /aCa/ for all places of articulation with simultaneous audio recording and probe-stabilized ultrasound (US). Three types of transcriptions were performed: (1) descriptive observations from the live US by the clinician recording the data, (2) US-aided transcription (UA) by two US-trained clinicians, and (3) traditional phonetic transcription by two CLP specialists from audio recording. We compared the number of consonants identified as in error by each transcriber and then classified errors into eight different subcategories. RESULTS: Both UA and traditional transcription yielded similar error detection rates; however, these were significantly higher than the observations recorded live in the clinic. Interrater reliability for the US transcribers was substantial (κ = 0.65) compared to moderate (κ = 0.47) for the traditional transcribers. US transcribers were more likely to identify covert errors such as double articulations and retroflexion than the audio-only transcribers. CONCLUSION: UTI is a useful complement to traditional phonetic transcription for CLP speech.

Enabling New Articulatory Gestures in Children With Persistent Speech Sound Disorders Using Ultrasound Visual Biofeedback.

Purpose This study evaluated ultrasound visual biofeedback treatment for teaching new articulations to children with a wide variety of speech sound disorders. It was hypothesized that motor-based intervention incorporating ultrasound would lead to rapid acquisition of a range of target lingual gestures with generalization to untreated words. Method Twenty children aged 6-15 years with a range of mild to severe speech disorders affecting a variety of lingual targets enrolled in a case series with replication. Of these, 15 children completed the intervention. All of the children presented with a variety of errors. We therefore employed a target selection strategy to treat the most frequent lingual error. These individual speech targets were treated using ultrasound visual biofeedback as part of ten to twelve 1-hr intervention sessions. The primary outcome measure was percentage of target segments correct in untreated wordlists. Results Six children were treated for velar fronting; 3 children, for postalveolar fronting; 2 children, for backing alveolars to pharyngeal or glottal place; 1 child, for debuccalization (production of all onsets as [h]); 1 child, for vowel merger; and 2 children, for lateralized sibilants. Ten achieved the new articulation in the 1st or 2nd session of intervention, despite no children being readily stimulable for their target articulation before intervention. In terms of generalization, effect sizes for percentage of target segments correct ranged from no effect (5 children), small effect (1 child), medium effect (4 children), and large effect (5 children). Conclusions Ultrasound visual biofeedback can be used to treat a wide range of lingual errors in children with various speech sound disorders, from mild to severe. Visual feedback may be useful for establishing new articulations; however, generalization is more variable.

Covert contrast and covert errors in persistent velar fronting.

Acoustic and articulatory studies demonstrate covert contrast in perceptually neutralised phonemic contrasts in both typical children and children with speech disorders. These covert contrasts are thought to be relatively common and symptomatic of phonetic speech disorders. However, clinicians in the speech therapy clinic have had no easy way of identifying this covertness. This study uses ultrasound tongue imaging to compare tongue contours for /t/and /k/in seven children with persistent velar fronting. We present a method of overlaying tongue contours to identify covert contrast at the articulatory level. Results show that all seven children, contrary to expectations, produced both /t/and /k/with near-identical tongue shapes showing no evidence of covert contrast. However, further analysis of one of the participants showed highly variable tongue shapes for /t/and /k/, including retroflex productions of both. Although not phonologically conditioned, this covert error is evidence of speech disorder at the phonetic level.

Using ultrasound visual biofeedback to treat persistent primary speech sound disorders.

Growing evidence suggests that speech intervention using visual biofeedback may benefit people for whom visual skills are stronger than auditory skills (for example, the hearing-impaired population), especially when the target articulation is hard to describe or see. Diagnostic ultrasound can be used to image the tongue and has recently become more compact and affordable leading to renewed interest in it as a practical, non-invasive visual biofeedback tool. In this study, we evaluate its effectiveness in treating children with persistent speech sound disorders that have been unresponsive to traditional therapy approaches. A case series of seven different children (aged 6-11) with persistent speech sound disorders were evaluated. For each child, high-speed ultrasound (121 fps), audio and lip video recordings were made while probing each child's specific errors at five different time points (before, during and after intervention). After intervention, all the children made significant progress on targeted segments, evidenced by both perceptual measures and changes in tongue-shape.

Advances in EPG for treatment and research: an illustrative case study.

Electropalatography (EPG), a technique which reveals tongue-palate contact patterns over time, is a highly effective tool for speech research. We report here on recent developments by Articulate Instruments Ltd. These include hardware for Windows-based computers, backwardly compatible (with Reading EPG3) software systems for clinical intervention and laboratory-based analysis for EPG and acoustic data, and an enhanced clinical interface with client and file management tools. We focus here on a single case study of a child aged 10+/-years who had been diagnosed with an intractable speech disorder possibly resulting ultimately from a complete cleft of hard and soft palate. We illustrate how assessment, diagnosis and treatment of the intractable speech disorder are undertaken using this new generation of instrumental phonetic support. We also look forward to future developments in articulatory phonetics that will link EPG with ultrasound for research and clinical communities.

Chewing and swallowing after surgical treatment for oral cancer: functional evaluation in 196 selected cases.

One hundred ninety-six patients treated for oral cancer between 1992 and 1999 self-scored their speech, chewing, and swallowing using a new self-questionnaire (Functional Intraoral Glasgow Scale) developed at Canniesburn Hospital, Glasgow, to assess the functional efficiency of patients treated for intraoral cancer. The patients were distributed into 12 homogeneous groups, according to the site and size of surgical resection, carefully mapped out on standard diagrams of the oral cavity. The functional outcome for chewing and swallowing was correlated to the site and size of resected tissue, to the reconstruction modality, and to radiotherapy and compared with the speech quality. The general trend is very similar for both chewing and swallowing; the smaller the resections, the better the functional outcome. Chewing was mostly affected by resections of the floor of the mouth, whereas swallowing was mostly affected by demolition of the base of the tongue and of the retromolar trigone. Speech showed a better postoperative recovery than chewing and swallowing. The reconstruction modality did not influence the eventual outcome for either function. Radiotherapy in combination with surgery is a negative functional prognostic factor. A correlation between site and size of excision and functional outcome is presented using color multiple-view diagrams for immediate appreciation to identify positive and negative prognostic factors.

Objective assessment of speech after surgical treatment for oral cancer: experience from 196 selected cases.

In 1992, a personal computer-based workstation for speech-digitized analysis was developed in conjunction with Canniesburn Hospital and Edinburgh University to measure all dispersion in speech after surgery for oral cancer. The voices of 196 patients with tumor of the oral cavity were recorded preoperatively and postoperatively. Surgical resection was carefully mapped out on standard diagrams of the oral cavity. Patients' recordings were assessed for conversational understandability by two referees. Patients also self-scored their speech using the Functional Intraoral Glasgow Scale self-questionnaire. Many patients had similar if not identical resections; therefore, 12 homogeneous groups were identified. Functional outcome for speech was correlated with the site and size of resected tissue and with the reconstruction modalities. The original association of an objective, computer-based tool and two subjective assessment tools proved to be the most suitable investigation method for speech. The general pattern was for consistently better speech quality with smaller excisions. The reconstruction modalities did not seem to influence the overall speech quality, as it was related mainly to the extent of surgical demolition. The authors present a detailed correlation between site and size of excision and functional outcome using color multiple-view diagrams for immediate appreciation. Positive and negative prognostic factors were identified in surgery for oral cancer.