Tongue shapes for rhotics in school-age children with and without residual speech errors

The Articulatory and Acoustic Representation of Second-Language French Vowels

This study examines how L1 English-L2 French learners use L1 articulatory and acoustic categories to produce L2 vowels that are both similar to and different from their L1 vowels. Previous studies examining the relationship between L1 and L2 sound inventories have found that learners reuse L1 phone categories to produce L2 phones that are perceived as similar, but importantly, there is a lack of articulatory data included in these types of studies, which has reinforced the assumption that vowel categories can be solely represented by their acoustic properties. The present study uses ultrasound tongue imaging data and videos of lip rounding in addition to acoustic data to examine how L1 English-L2 French learners produce the French vowels /i y u e ø o/ compared with their English vowels /i u e o/. The results focus on individual paths to category formation to show how learners articulate L2 vowels, and reveal that they tend to reuse L1 tongue body gestures to produce the French vowels /i u e o/, and lip rounding gestures to produce the round vowels /y u o/. This study demonstrates that transfer of articulatory gestures depends on vowel quality and emphasizes the importance of using articulatory data to inform theories of L2 category formation.

Assessing ultrasound probe stabilization for quantifying speech production contrasts using the Adjustable Laboratory Probe Holder for UltraSound (ALPHUS)

Ultrasound imaging of the tongue is biased by the probe movements relative to the speaker's head. Two common remedies are restricting or algorithmically compensating for such movements, each with its own challenges. We describe these challenges in details and evaluate an open-source, adjustable probe stabilizer for ultrasound (ALPHUS), specifically designed to address these challenges by restricting uncorrectable probe movements while allowing for correctable ones (e.g., jaw opening) to facilitate naturalness. The stabilizer is highly modular and adaptable to different users (e.g., adults and children) and different research/clinical needs (e.g., imaging in both midsagittal and coronal orientations). The results of three experiments show that probe movement over uncorrectable degrees of freedom was negligible, while movement over correctable degrees of freedom that could be compensated through post-processing alignment was relatively large, indicating unconstrained articulation over parameters relevant for natural speech. Results also showed that probe movements as small as 5 mm or 2 degrees can neutralize phonemic contrasts in ultrasound tongue positions. This demonstrates that while stabilized but uncorrected ultrasound imaging can provide reliable tongue shape information (e.g., curvature or complexity), accurate tongue position (e.g., height or backness) with respect to vocal tract hard structure needs correction for probe displacement relative to the head.

Tongue Shape Complexity in Children With and Without Speech Sound Disorders

PURPOSE

This study investigates the hypothesis that younger speakers and speakers with more severe speech sound disorders are more likely to use simpler (undifferentiated) tongue gestures due to difficulties with, or immaturity of, lingual motor control.

METHOD

The hypothesis is tested using cross-sectional secondary data analysis of synchronous audio and high-speed ultrasound recordings from children with idiopathic speech sound disorders (n = 30, aged 5;0-12;11 [years;months]) and typically developing children (n = 29, aged 5;8-12;10), producing /a/, /t/, /ɹ/, /l/, /s/, and /ʃ/ in an intervocalic /aCa/ environment. Tongue shape complexity is measured using NINFL (Number of INFLections) and modified curvature index (MCI) from splines fitted to ultrasound images at the point of maximal lingual gesture. Age, perceived accuracy, and consonant are used as predictors.

RESULTS

The results suggest that as age increases, children with speech sound disorders have lower MCI compared to typically developing children. Increase in age also led to decrease of MCI for the typically developing group. In the group of children with speech sound disorders, perceptually incorrect /ɹ/ productions have lower MCI than correct productions, relative to /a/.

CONCLUSIONS

There is some evidence of systematic tongue shape complexity differences between typically developing children and children with speech sound disorders when accounting for increase in age. Among children with speech sound disorders, increase in age and perceptually incorrect consonant realizations are associated with decreasing tongue shape complexity.

Effects of Production Training With Ultrasound Biofeedback on Production and Perception of Second-Language English Tense-Lax Vowel Contrasts

PURPOSE

This study investigated the efficacy of ultrasound biofeedback compared to a traditional acoustic input-only method in the second-language (L2) production training of English tense-lax vowel contrasts (/i-ɪ/ and /e-ɛ/). The relationship between the degrees of production and perception learning was also examined to explore a potential L2 production-perception link.

METHOD

Using a pretest/training/posttest paradigm, two groups of native Mandarin speakers received three sessions of training, one with ultrasound and one with audio only. Perception performance was measured by accuracy in AX discrimination. Production performance was measured in terms of accuracy in repetition production and Euclidean distance between contrasting vowels.

RESULTS

Both groups showed significant improvements in posttest production and perception tasks. Additionally, the training benefits were retained 6 weeks after training. The two groups, however, did not differ significantly in training gains; nor was there a significant correlation between training-induced changes in perception and production performance.

CONCLUSIONS

The results indicate that ultrasound feedback is similarly effective as the audio-only training in improving the L2 production of English tense-lax contrasts and the benefits transferred to perception. The lack of correlation between production and perception gains suggests that the two modalities need to be separately trained to achieve desired L2 learning outcomes.

Classification of accurate and misarticulated /r/ for ultrasound biofeedback using tongue part displacement trajectories

Ultrasound biofeedback therapy (UBT), which incorporates real-time imaging of tongue articulation, has demonstrated generally positive speech remediation outcomes for individuals with residual speech sound disorder (RSSD). However, UBT requires high attentional demands and may therefore benefit from a simplified display of articulation targets that are easily interpretable and can be compared to real-time articulation. Identifying such targets requires automatic quantification and analysis of movement features relevant to accurate speech production. Our image-analysis program TonguePART automatically quantifies tongue movement as tongue part displacement trajectories from midsagittal ultrasound videos of the tongue, with real-time capability. The present study uses such displacement trajectories to compare accurate and misarticulated American-English rhotic /ɑr/ productions from 40 children, with degree of accuracy determined by auditory perceptual ratings. To identify relevant features of accurate articulation, support vector machine (SVM) classifiers were trained and evaluated on several candidate data representations. Classification accuracy was up to 85%, indicating that quantification of tongue part displacement trajectories captured tongue articulation characteristics that distinguish accurate from misarticulated production of /ɑr/. Regression models for perceptual ratings were also compared. The simplest data representation that retained high predictive ability, demonstrated by high classification accuracy and strong correlation between observed and predicted ratings, was displacements at the midpoint of /r/ relative to /ɑ/ for the tongue dorsum and blade. This indicates that movements of the dorsum and blade are especially relevant to accurate production of /r/, suggesting that a predictive parameter and biofeedback target based on this data representation may be usable for simplified UBT.

Comparing metrics for quantification of children's tongue shape complexity using ultrasound imaging

Speech sound disorders can pose a challenge to communication in children that may persist into adulthood. As some speech sounds are known to require differential control of anterior versus posterior regions of the tongue body, valid measurement of the degree of differentiation of a given tongue shape has the potential to shed light on development of motor skill in typical and disordered speakers. The current study sought to compare the success of multiple techniques in quantifying tongue shape complexity as an index of degree of lingual differentiation in child and adult speakers. Using a pre-existing data set of ultrasound images of tongue shapes from adult speakers producing a variety of phonemes, we compared the extent to which three metrics of tongue shape complexity differed across phonemes/phoneme classes that were expected to differ in articulatory complexity. We then repeated this process with ultrasound tongue shapes produced by a sample of young children. The results of these comparisons suggested that a modified curvature index and a metric representing the number of inflection points best reflected small changes in tongue shapes across individuals differing in vocal tract size. Ultimately, these metrics have the potential to reveal delays in motor skill in young children, which could inform assessment procedures and treatment decisions for children with speech delays and disorders.

Characterizing sensorimotor profiles in children with residual speech sound disorder: a pilot study

PURPOSE

Children with speech errors who have reduced motor skill may be more likely to develop residual errors associated with lifelong challenges. Drawing on models of speech production that highlight the role of somatosensory acuity in updating motor plans, this pilot study explored the relationship between motor skill and speech accuracy, and between somatosensory acuity and motor skill in children. Understanding the connections among sensorimotor measures and speech outcomes may offer insight into how somatosensation and motor skill cooperate during speech production, which could inform treatment decisions for this population.

METHOD

Twenty-five children (ages 9-14) produced syllables in an /ɹ/ stimulability task before and after an ultrasound biofeedback treatment program targeting rhotics. We first tested whether motor skill (as measured by two ultrasound-based metrics of tongue shape complexity) predicted acoustically measured accuracy (the normalized difference between the second and third formant frequencies). We then tested whether somatosensory acuity (as measured by an oral stereognosis task) predicted motor skill, while controlling for auditory acuity.

RESULTS

One measure of tongue shape complexity was a significant predictor of accuracy, such that higher tongue shape complexity was associated with lower accuracy at pre-treatment but higher accuracy at post-treatment. Based on the same measure, children with better somatosensory acuity produced /ɹ/ tongue shapes that were more complex, but this relationship was only present at post-treatment.

CONCLUSION

The predicted relationships among somatosensory acuity, motor skill, and acoustically measured /ɹ/ production accuracy were observed after treatment, but unexpectedly did not hold before treatment. The surprising finding that greater tongue shape complexity was associated with lower accuracy at pre-treatment highlights the importance of evaluating tongue shape patterns (e.g., using ultrasound) prior to treatment, and has the potential to suggest that children with high tongue shape complexity at pre-treatment may be good candidates for ultrasound-based treatment.

Perceptive-auditive and perceptive-visual judgment in the identification of gradient productions in fricatives

PURPOSE

To analyze which method of judgment, auditory- perceptual (PAJ) of audios or perceptual-visual judgment (PVJ) (ultrasound images), is more sensitive to detect gradual productions between the class of deaf coronal fricatives and check if there is a correlation between these forms of judgment.

METHOD

Audio and video files of language ultrasound (LUS) related to the production of the words "frog" and "key", of 11 children, between 6 and 12 years old, with atypical speech production, were selected from a bank data and edited for judgments. After instruction and prior training, 20 judges should choose, immediately upon presentation of the stimulus (auditory or visual), one of three options arranged on the computer screen. In PAJ the options were: correct, incorrect or gradient production, while in PVJ the options were images corresponding to the production of [s], [∫] or undifferentiated. The presentation time of the stimuli and the reaction time were automatically controlled by the PERCEVAL software.

RESULTS

PVJ provided a higher percentage of identification of gradient stimuli and a shorter reaction time in performing the task compared to PAJ, both statistically significant. Spearman's correlation test did not show statistical significance between PAJ and PVJ responses, nor for reaction time.

CONCLUSION

PVJ using US images proved to be the most sensitive method for detecting gradient production in the production of fricatives [s] and [∫], and can be used as a complementary method to PAJ in speech analysis.

Extending Ultrasound Tongue Shape Complexity Measures to Speech Development and Disorders

Purpose Generalizations can be made about the order in which speech sounds are added to a child's phonemic inventory and the ways that child speech deviates from adult targets in a given language. Developmental and disordered speech patterns are presumed to reflect differences in both phonological knowledge and skilled motor control, but the relative contribution of motor control remains unknown. The ability to differentially control anterior versus posterior regions of the tongue increases with age, and thus, complexity of tongue shapes is believed to reflect an individual's capacity for skilled motor control of speech structures. Method The current study explored the relationship between tongue complexity and phonemic development in children (ages 4-6 years) with and without speech sound disorder producing various phonemes. Using established metrics of tongue complexity derived from ultrasound images, we tested whether tongue complexity incrementally increased with age in typical development, whether tongue complexity differed between children with and without speech sound disorder, and whether tongue complexity differed based on perceptually rated accuracy (correct vs. incorrect) for late-developing phonemes in both diagnostic groups. Results Contrary to hypothesis, age was not significantly associated with tongue complexity in our typical child sample, with the exception of one association between age and complexity of /t/ for one measure. Phoneme was a significant predictor of tongue complexity, and typically developing children had more complex tongue shapes for /ɹ/ than children with speech sound disorder. Those /ɹ/ tokens that were rated as perceptually correct had higher tongue complexity than the incorrect tokens, independent of diagnostic classification. Conclusions Quantification of tongue complexity can provide a window into articulatory patterns characterizing children's speech development, including differences that are perceptually covert. With the increasing availability of ultrasound imaging, these measures could help identify individuals with a prominent motor component to their speech sound disorder and could help match those individuals with a corresponding motor-based treatment approach. Supplemental Material https://doi.org/10.23641/asha.14880039.

Neuroimaging of the Syllable Repetition Task in Children With Residual Speech Sound Disorder

Purpose This study investigated phonological and speech motor neural networks in children with residual speech sound disorder (RSSD) during an overt Syllable Repetition Task (SRT). Method Sixteen children with RSSD with /ɹ/ errors (6F [female]; ages 8;0-12;6 [years;months]) and 16 children with typically developing speech (TD; 8F; ages 8;5-13;7) completed a functional magnetic resonance imaging experiment. Children performed the SRT ("SRT-Early Sounds") with the phonemes /b, d, m, n, ɑ/ and an adapted version ("SRT-Late Sounds") with the phonemes /ɹ, s, l, tʃ, ɑ/. We compared the functional activation and transcribed production accuracy of the RSSD and TD groups during both conditions. Expected errors were not scored as inaccurate. Results No between-group or within-group differences in repetition accuracy were found on the SRT-Early Sounds or SRT-Late Sounds tasks at any syllable sequence length. On a first-level analysis of the tasks, the TD group showed expected patterns of activation for both the SRT-Early Sounds and SRT-Late Sounds, including activation in the left primary motor cortex, left premotor cortex, bilateral anterior cingulate, bilateral primary auditory cortex, bilateral superior temporal gyrus, and bilateral insula. The RSSD group showed similar activation when correcting for multiple comparisons. In further exploratory analyses, we observed the following subthreshold patterns: (a) On the SRT-Early Sounds, greater activation was found in the left premotor cortex for the RSSD group, while greater activation was found in the left cerebellum for the TD group; (b) on the SRT-Late Sounds, a small area of greater activation was found in the right cerebellum for the RSSD group. No within-group functional differences were observed (SRT-Early Sounds vs. SRT-Late Sounds) for either group. Conclusions Performance was similar between groups, and likewise, we found that functional activation did not differ. Observed functional differences in previous studies may reflect differences in task performance, rather than fundamental differences in neural mechanisms for syllable repetition.

Children's English Consonant Acquisition in the United States: A Review

Purpose Speech-language pathologists' clinical decision making and consideration of eligibility for services rely on quality evidence, including information about consonant acquisition (developmental norms). The purpose of this review article is to describe the typical age and pattern of acquisition of English consonants by children in the United States. Method Data were identified from published journal articles and assessments reporting English consonant acquisition by typically developing children living in the United States. Sources were identified through searching 11 electronic databases, review articles, the Buros database, and contacting experts. Data describing studies, participants, methodology, and age of consonant acquisition were extracted. Results Fifteen studies (six articles and nine assessments) were included, reporting consonant acquisition of 18,907 children acquiring English in the United States. These cross-sectional studies primarily used single-word elicitation. Most consonants were acquired by 5;0 (years;months). The consonants /b, n, m, p, h, w, d/ were acquired by 2;0-2;11; /ɡ, k, f, t, ŋ, j/ were acquired by 3;0-3;11; /v, ʤ, s, ʧ, l, ʃ, z/ were acquired by 4;0-4;11; /ɹ, ð, ʒ/ were acquired by 5;0-5;11; and /θ/ was acquired by 6;0-6;11 (ordered by mean age of acquisition, 90% criterion). Variation was evident across studies resulting from different assessments, criteria, and cohorts of children. Conclusions These findings echo the cross-linguistic findings of McLeod and Crowe (2018) across 27 languages that children had acquired most consonants by 5;0. On average, all plosives, nasals, and glides were acquired by 3;11; all affricates were acquired by 4;11; all liquids were acquired by 5;11; and all fricatives were acquired by 6;11 (90% criterion). As speech-language pathologists apply this information to clinical decision making and eligibility decisions, synthesis of knowledge from multiple sources is recommended.

Tutorial: Motor-Based Treatment Strategies for /r/ Distortions

Purpose This tutorial summarizes current best practices in treating American English /r/ distortions in children with residual speech errors. Method To enhance the effectiveness of clinicians' cueing and feedback, the phonetics of /r/ production is reviewed. Principles of acquisition, which can inform how to practice /r/ in the early stages of therapy, are explained. Elements of therapy that lack scientific support are also mentioned. Results Although there is significant variability in /r/ production, the common articulatory requirements include an oral constriction, a pharyngeal constriction, tongue body lowering, lateral bracing, and slight lip rounding. Examples of phonetic cues and shaping strategies are provided to help clinicians elicit these movements to evoke correct /r/ productions. Principles of acquisition (e.g., blocked practice, frequent knowledge of performance feedback) are reviewed to help clinicians structure the earliest stages of treatment to establish /r/. Examples of approaches that currently lack scientific support include nonspeech oral motor exercises, tactile cues along the mylohyoid muscle, and heterogeneous groupings in group therapy. Conclusion Treatment strategies informed by phonetic science and motor learning theory can be implemented by all clinicians to enhance acquisition of /r/ for children with residual errors. Supplemental Material https://doi.org/10.23641/asha.12771329.