The effects of English proficiency on the processing of Bulgarian-accented English by Bulgarian-English bilinguals

This dissertation explores the potential benefit of listening to and with one’s first-language accent, as suggested by the Interspeech Intelligibility Benefit Hypothesis (ISIB). Previous studies have not consistently supported this hypothesis. According to major second language learning theories, the listener’s second language proficiency determines the extent to which the listener relies on their first language phonetics. Hence, this thesis provides a novel approach by focusing on the role of English proficiency in the understanding of Bulgarian-accented English for Bulgarian-English bilinguals. The first experiment investigated whether evoking the listeners’ L1 Bulgarian phonetics would improve the speed of processing Bulgarian-accented English words, compared to Standard British English words, and vice versa. Listeners with lower English proficiency processed Bulgarian-accented English faster than SBE, while high proficiency listeners tended to have an advantage with SBE over Bulgarian accent. The second experiment measured the accuracy and reaction times (RT) in a lexical decision task with single-word stimuli produced by two L1 English speakers and two Bulgarian-English bilinguals. Listeners with high proficiency in English responded slower and less accurately to Bulgarian-accented speech compared to L1 English speech and compared to lower proficiency listeners. These accent preferences were also supported by the listener’s RT adaptation across the first experimental block. A follow-up investigation compared the results of L1 UK English listeners to the bilingual listeners with the highest proficiency in English. The L1 English listeners and the bilinguals processed both accents with similar speed, accuracy and adaptation patterns, showing no advantage or disadvantage for the bilinguals. These studies support existing models of second language phonetics. Higher proficiency in L2 is associated with lesser reliance on L1 phonetics during speech processing. In addition, the listeners with the highest English proficiency had no advantage when understanding Bulgarian-accented English compared to L1 English listeners, contrary to ISIB. Keywords: Bulgarian-English bilinguals, bilingual speech processing, L2 phonetic development, lexical decision, proficienc

Tongue shape complexity in children with speech sound disorders

Purpose This study investigates the hypothesis that younger speakers and speakers with more severe speech sound disorders (SSD) are more likely to use undifferentiated tongue gestures due to difficulties with lingual motor control (Gibbon 1999). Kabakoff et al. (2021) measured the number of tongue inflections (NINFL) using ultrasound tongue imaging (UTI) and showed that children with SSD have lower tongue complexity when producing /ɹ/ than typically developing (TD) children. They also reported that younger children had higher complexity for /t/ than older children. Method Children with idiopathic SSD (n=23, aged 5;2-12;11) and without SSD (n=24, aged 5;8-12;11) had high-speed ultrasound and audio recordings made by a Speech and Language Therapist. The children with SSD produced 10 repetitions of /p, t, k, j, ɹ, l, w, s, θ, ʃ/ an /aCa/ environment and those without SSD produced one repetition. Percent tokens correct (PTC) per consonant were measured by a Speech and Language Therapist using ultrasound and audio recordings and used as proxy for the severity of the SSD for that consonant. PTC of the TD children was 100% throughout. NINFL was measured automatically using AAA software after fitting tongue splines at the point of maximal lingual gesture. A mixed effects ordinal regression model was used for analysis: NINFL (range:1 to 5) ~ Age (in months, scaled)*PTC (scaled)*Consonant (baseline /p/) + (1 + Consonant (baseline /p/) | Speaker). Results There were significant effects of Age, PTC, and Consonant (for /j/ and /t/ compared to /p/). For average age and PTC, /t/ had lower NINFL than /p/ and /j/ had higher NINFL. There was a significant interaction between Age and PTC for baseline /p/. There was a significant interaction between Age and Consonant for average PTC. For children with average PTC, increase in age led to increase in NINFL for /p/ but not as steep of an increase for /w/, /ɹ/, /ʃ/ and /s/. There was a significant interaction between PTC and Consonant. For average-aged children in the sample, an increase in PTC led to an increase in NINFL for /ɹ/, /ʃ/, /s/, /θ/, /t/ compared to /p/. Lastly, there was a significant triple interaction between Age, PTC, and Consonant. Increase in age and PTC led to increasing NINFL for /ɹ/, /ʃ/, /s/, /θ/ compared to /p/. The raw data is illustrated in Figures 1 and 2. Conclusions The significant interactions between age, severity of the specific sound distortion and consonant suggest that “correct” realisations of sounds may involve different levels of tongue complexity across ages depending on phoneme. Increase in age and accuracy of productions led to increase in lingual complexity in some circumstances for /ɹ/, /ʃ/, /s/, /θ/, /t/, supporting the initial hypothesis. References Gibbon, F. E. (1999). Undifferentiated Lingual Gestures in Children With Articulation/Phonological Disorders. Journal of Speech, Language, and Hearing Research, 42(2), 382–397. https://doi.org/10.1044/jslhr.4202.382 Kabakoff, H., Harel, D., Tiede, M., Whalen, D. H., & McAllister, T. (2021). Extending Ultrasound Tongue Shape Complexit

Protocol for SonoSpeech Cleft Pilot : a mixed-methods pilot randomized control trial of ultrasound visual biofeedback versus standard intervention for children with cleft lip and palate

Background: Children with cleft lip and palate can continue to have problems producing clear speech after surgery. This can lead to social, emotional, and educational challenges. Typical treatment involves teaching children the correct tongue movements to produce speech sounds. This is known as articulation intervention. However, this intervention is challenging because the tongue is hidden from view and movements are difficult to see and describe. This pilot randomized control trial will try a new treatment, ultrasound visual biofeedback (U-VBF) versus standard articulatory intervention for children with cleft lip and palate, as comparison. Feasibility outcomes will be determined. Methods/design: The Sonospeech project will enroll up to 40 children with cleft lip and palate aged 4;6 to 16 in a mixed-methods randomized controlled trial with blinded assessors. Children will receive either six sessions of U-VBF or articulation intervention. The primary goals of this pilot are to assess the feasibility and inform the design of a full-scale RCT of U-VBF for children with cleft speech characteristics. This will be achieved by determining the following outcome measures: recruitment/attrition rates; measures of pre-post follow-up completion; and acceptability of the randomization and interventions to families. Discussion: Larger trials of speech interventions for children with cleft lip and palate are needed. This pilot/feasibility study will determine whether a larger randomized control trial comparing ultrasound and articulation interventions is feasible. Trial registration: ISRCTN, ISRCTN17441953. Registered 22 March 2021. See Table 2 in Appendix 1 for all items

Matched-accent processing: Bulgarian-English bilinguals do not have a processing advantage with Bulgarian-accented English over native English speech

James Scobbie - ORCID: 0000-0003-4509-6782 https://orcid.org/0000-0003-4509-6782Robin Lickley - ORCID: 0000-0003-2583-5461 https://orcid.org/0000-0003-2583-5461The Interlanguage Intelligibility Benefit hypothesis (ISIB) for Talkers suggests that there is a potential benefit when listening to one’s second language when it is produced in the accent of one’s first language (matched-accent processing). This study explores ISIB, considering listener proficiency. According to second language learning theories, the listener’s second language proficiency determines the extent to which they rely on their first language phonetics, hence the magnitude of ISIB may be affected by listener proficiency. The accuracy and reaction times of Bulgarian-English bilinguals living in the UK were recorded in a lexical decision task. The English stimuli were produced by native English speakers and Bulgarian-English bilinguals. Listeners responded more slowly and less accurately to the matched-accent stimuli than the native English stimuli. In addition, they adapted their reaction times faster to new speakers with a native English accent compared to a Bulgarian accent. However, the listeners with the lowest English proficiency had no advantage in reaction times and accuracy for either accent. The results offer mixed support for ISIB for Talkers and are consistent with second language learning theories, according to which listeners rely less on their native language phonology when their proficiency in the second language has increased.This study was funded by the full-time doctoral bursary of Queen Margaret University.https://www.journal-labphon.org/inpressinpres

An ultrasound investigation of tongue dorsum raising in children with cleft palate +/- cleft lip

Objective: This study aimed to determine whether overuse of the tongue dorsum, or back, is evident in children with repaired cleft palate with or without cleft lip (CP+/-CL). We hypothesized that children with CP+/-CL would show overuse of the tongue dorsum, a compensatory pattern. Method: Secondary data analysis of mid-sagittal ultrasound tongue imaging data from 31 children with CP+/-CL and 29 typically developing children were used. We annotated the consonants /ʃ, t, s, k/ at the point of maximum constriction in an /aCa/ environment. Children with CP+/-CL said the tokens 10 times, typically developing children said them once. We automatically fitted splines to the tongue contour and extracted the Dorsum Excursion Index (DEI) for each consonant. This metric measures the relative use of the tongue dorsum, with more posterior consonants having higher values. We compared DEI values across groups and consonants using a linear mixed effects model. DEI was predicted by the interaction of consonant (baseline: /ʃ/) and speaker type (baseline: TD), including by-speaker random slopes for consonant and random intercepts for speaker. Results: Overall DEI was not higher in children with CP+/-CL compared to typically developing children. Between groups the only significant difference was the position of /k/ relative to /ʃ/, where the difference between these two consonants was smaller in the children with CP+/-CL. Conclusions: There was no support for the hypothesis that overuse of the tongue dorsum is a common characteristic in children with repaired CP+/-CL. However, individual children may present with this pattern

Multidimensional signals and analytic flexibility : estimating degrees of freedom in human speech analyses

Recent empirical studies have highlighted the large degree of analytic flexibility in data analysis which can lead to substantially different conclusions based on the same data set. Thus, researchers have expressed their concerns that these researcher degrees of freedom might facilitate bias and can lead to claims that do not stand the test of time. Even greater flexibility is to be expected in fields in which the primary data lend themselves to a variety of possible operationalizations. The multidimensional, temporally extended nature of speech constitutes an ideal testing ground for assessing the variability in analytic approaches, which derives not only from aspects of statistical modeling, but also from decisions regarding the quantification of the measured behavior. In the present study, we gave the same speech production data set to 46 teams of researchers and asked them to answer the same research question, resulting in substantial variability in reported effect sizes and their interpretation. Using Bayesian meta-analytic tools, we further find little to no evidence that the observed variability can be explained by analysts' prior beliefs, expertise or the perceived quality of their analyses. In light of this idiosyncratic variability, we recommend that researchers more transparently share details of their analysis, strengthen the link between theoretical construct and quantitative system and calibrate their (un)certainty in their conclusions

A pilot fieldwork ultrasound study of tongue shape variability in children with and without speech sound disorder

Children with Speech Sound Disorders (SSD) have been described as having increased tongue shape variability during speech. However, most studies do not compare this variability to typically developing children (TD) using ultrasound tongue imaging (UTI). Open access corpora suitable for answering this question are scarce. This pilot study addresses both the theoretical question of whether variability differs between TD children and children with SSDs; and the feasibility of a potential solution for acquiring ultrasound data quickly at a public science exhibition. We compare tongue shapes during multiple repetitions of various consonants in TD children across different ages, and children with SSD, using mean Nearest Neighbour Distance (NND). Results suggest no significant effect of age in the TD group. Children with SSD had significantly higher tongue shape variability than TD children. Field data collection was a viable method for collecting UTI data, despite some limitations

Bulgarian vowel reduction in unstressed position : an ultrasound and acoustic investigation

Vowel reduction in Contemporary Standard Bulgarian (CSB) has been variously claimed to involve raising, no change or lowering of the high vowels /iəu/. There is a general agreement that the low vowels /ɛaɔ/ are raised when unstressed. This paper directly measures tongue height using Ultrasound Tongue Imaging (UTI) and relates this measure to the acoustic correlate F1 at vowel midpoint. The six vowels of CSB were paired with respect to frontness (/ɛ, i/, /a, ə/, /ɔ, u/), and the overlap in height of the unstressed lower vowel in each pair was assessed relative to (a) its stressed counterpart and (b) the stressed and (c) unstressed realisations of the lower vowel. There was no evidence of the higher unstressed vowel in each pair being different from its stressed counterpart. The articulatory and acoustic results are not completely aligned, but both diverge from the traditional model of vowel reduction in CSB