Voice Onset Time of Greek Stops Productions by Greek Children with Cochlear Implants and Normal Hearing.

INTRODUCTION: Research on voice onset time (VOT) production of stops in children with CI versus NH has reported conflicting results. Effects of age and place of articulation on VOT have not been examined for children with CI. The purpose of this study was to examine VOT production by Greek-speaking children with CI in comparison to NH controls, with a focus on the effects of age, type of stimuli, and place of articulation. METHODS: Participants were 24 children with CI aged from 2;8 to 13;3 years and 24 age- and gender-matched children with NH. Words were elicited via a picture-naming task, and nonwords were elicited via a fast mapping procedure. RESULTS: For voiced stops, children with CI showed longer VOT than children with NH, whereas VOT for voiceless stops was similar to that of NH peers. Also, in both voiced and voiceless stops, the VOT differed as a function of age and place of articulation across groups. Differences as a function of stimulus type were only noted for voiced stops across groups. CONCLUSIONS: For the voiced stop consonants, which demand more articulatory effort, VOT production in children with CI was longer than in children with NH. For the voiceless stop consonants, VOT production in children with CI is acquired at a young age.

Preface to the special issue "Typical and atypical speech development in Greek".

This special issue of Clinical Linguistics and Phonetics presents a selection of papers, four in total, from the first thematic workshop entitled "Phonetic/phonological aspects of typical and atypical speech development with emphasis on Greek" which took place during the 25th International Symposium on Theoretical and Applied Linguistics held at Aristotle University in Thessaloniki in May 2022. It also includes one additional contribution within the thematic scope of the volume that was submitted to the journal independently of the workshop. Papers examine data from different clinical populations, including a clinical case study, as well as data or theoretical background from typical groups. They address aspects of speech production in childhood, adolescence and early adulthood. They thus reflect the aim of the workshop which was to provide a forum to researchers for the exchange of findings covering different populations (typical and clinical), age groups, genders, and various aspects of production. The ultimate goal was the formation of a working group that would bring together researchers with a special interest in phonetics and phonology, explore factors that influence speech acquisition and development in typical and atypical populations, convene and discuss present and future directions in speech acquisition and development with emphasis on the Greek language.

Temporal, spectral and amplitude characteristics of the Greek fricative /s/ in hearing-impaired and normal-hearing speech.

Fricatives, and especially sibilants, are very frequently misarticulated by speakers with hearing loss. Misarticulations can result in phonemic contrast weakening or loss, compromising intelligibility. The present study focuses on the examination of acoustic characteristics of the Greek alveolar fricative /s/, an articulatorily demanding sound, produced by young adult speakers with profound hearing impairment and with normal hearing. An array of variables was examined using mixed-effects and random forest models aiming to assess the effectiveness of various measures in differentiating hearing-impaired and normal-hearing /s/ production. Significant differences were found in spectral and amplitude measures, but not in temporal measures. In hearing-impaired speech, spectral slope and RMS amplitude had significantly lower values, indicating a more distributed spectrum, suggestive of decreased flow velocity through the fricative constriction. Also, a trend for concentration of energy at lower frequencies was observed suggesting more posterior fricative articulation than normal. Moreover, measures capturing the variation of frequency and amplitude over time revealed different patterns of sibilance development across time than normal, denoting the production of a less well-formed or less sibilant /s/ by speakers with hearing impairment. The investigation of contextual effects on /s/ in hearing-impaired speech showed increased spectral variance, negative skewness and lower kurtosis in the labial (rounded) context /u/ in relation to the nonlabial contexts /i/ and /a/, indicating a more diffuse, less compact spectrum with concentration at high frequencies. Findings are discussed in relation to previous literature on fricative production by speakers with hearing impairment and normal hearing in Greek and other languages.

Coarticulatory dynamics in Greek disyllables produced by young adults with and without hearing loss.

Hearing loss affects both speech perception and production with detrimental effects on various speech characteristics including coarticulatory dynamics. The aim of the present study is to explore consonant-to-vowel (C-to-V) and vowel-to-vowel (V-to-V) coarticulation in magnitude, direction and temporal extent in the speech of young adult male and female speakers of Greek with normal hearing (NH) and hearing impairment (HI). Nine intelligible speakers with profound HI, using conventional hearing aids, and five speakers with NH produced /pV1CV2/ disyllables, with the point vowels /i, a, u/ and the consonants /p, t, s/, stressed either on the first or the second syllable. Formant frequencies F1 and F2 were measured in order to examine C-to-V effects at vowel midpoint and V-to-V effects at vowel onset, midpoint and offset. The acoustic and statistical analyses revealed similarities but also significant differences regarding coarticulatory patterns of the two groups. Interestingly, prevalence of anticipatory coarticulation effects in alveolar contexts was observed for speakers with HI. Findings are interpreted on account of possible differences in articulation strategies between the two groups and with reference to current coarticulatory models.

Early cognitive assessment in premature infants: the discriminatory value of eye-tracking vs. Bayley Scales.

Introduction: The testing of visuocognitive development in preterm infants shows strong interactions between perinatal characteristics and cognition, learning and overall neurodevelopment evolution. The assessment of anticipatory gaze data of object-location bindings via eye-tracking can predict the neurodevelopment of preterm infants at the age of 3 years; little is known, however, about the early cognitive function and its assessment methods during the first year of life. Methods: The current study presents data from a novel assessment tool, a Delayed Match Retrieval (DMR) paradigm via eye-tracking was used to measure visual working memory (VWM) and attention skills. The eye-tracking task that was designed to measure infants' ability to actively localize objects and to make online predictions of object-location bindings. 63 infants participated in the study, 39 preterm infants and 24 healthy full term infants - at a corrected age of 8-9 months for premature infants and similar chronological age for full term infants. Infants were also administered the Bayley Scales of Infant and Toddler Development. Results: The analysis of the Bayley scores showed no significant difference between the two groups while the eye-tracking data showed a significant group effect on all measurements. Moreover, preterm infants' VWM performance was significantly lower than full term's. Birth weight affected the gaze time on all Areas Of Interest (AOIs), overall VWM performance and the scores at the Cognitive Bayley subscale. Furthermore, preterm infants with fetal growth restriction (FGR) showed significant performance effects in the eye-tracking measurements but not on their Bayley scores verifying the high discriminatory value of the eye gaze data. Conclusion: Visual working memory and attention as measured via eye-tracking is a non-intrusive, painless, short duration procedure (approx. 4-min) was found to be a significant tool for identifying prematurity and FGR effects on the development of cognition during the first year of life. Bayley Scales alone may not pick up these deficits. Identifying tools for early neurodevelopmental assessments and cognitive function is important in order to enable earlier support and intervention in the vulnerable group of premature infants, given the associations between foundational executive functional skills and later cognitive and academic ability.

Acquisition of initial /s/-stop and stop-/s/sequences in Greek.

Previous work on children's acquisition of complex sequences points to a tendency for affricates to be acquired before clusters, but there is no clear evidence of a difference in order of acquisition between clusters with /s/ that violate the Sonority Sequencing Principle (SSP), such as /s/ followed by stop in onset position, and other clusters that obey the SSP. One problem with studies that have compared the acquisition of SSP-obeying and SSP-violating clusters is that the component sounds in the two types of sequences were different.This paper examines the acquisition of initial /s/-stop and stop-/s/ sequences by sixty Greek children aged 2 through 5 years. Results showed greater accuracy for the /s/-stop relative to the stop-/s/ sequences, but no difference in accuracy between /ts/, which is usually analyzed as an affricate in Greek, and the other stop-/s/ sequences. Moreover, errors for the /s/-stop sequences and /ts/ primarily involved stop substitutions, whereas errors for /ps/ and /ks/ were more variable and often involved fricative substitutions, a pattern which may have a perceptual explanation. Finally, /ts/ showed a distinct temporal pattern relative to the stop-/s/ clusters /ps/ and /ks/, similar to what has been reported for productions of Greek adults.

Acoustic characteristics of vowels produced by Greek intelligible speakers with profound hearing impairment I: Examination of vowel space.

PURPOSE: The study examines F1, F2 and F3 formant frequencies of vowels produced by six Greek intelligible speakers with profound hearing impairment and six speakers with normal hearing (three male and three female in each group). METHOD: The formant frequencies are measured in words of the form /'pVCV/ where V = /i, , , , u/ and C = /p, t, k, s/. The study examines differences in formant frequencies between the two groups and as a function of gender. Three measures are calculated to examine the area of the vowel space and differences along the F1 and F2 axes between the groups and genders. RESULT: The results show that the vowel space produced by the speakers with hearing impairment is considerably reduced. Greater reduction was evident for F2 compared to F1. Restricted formant frequency ranges and relatively large variation along F1 and/or F2 for selected vowels resulted in overlap among vowel categories. F3 frequencies were systematically lower and showed greater variation for the speakers with hearing impairment. CONCLUSION: The paper discusses findings with reference to perceptual and production constraints affecting the speech of individuals with hearing impairment.

Acoustic characteristics of vowels produced by Greek intelligible speakers with profound hearing impairment II: The influence of stress and context.

PURPOSE: The present paper examines the influence of stress and context on selected acoustic characteristics of vowels produced by six adult Greek intelligible speakers with profound hearing impairment and six speakers with normal hearing (three males and three females in each group). METHOD: F1, F2 and F3 formant frequencies and the duration of vowels are measured in words of the form /(')pVCV/ with V = /i, ɛ, ɐ, ɔ, u/ and C = /p, t, k, s/. Variation in these parameters due to context and stress is reported for the two genders. A co-articulatory measure and three measures that examine the area of the vowel space and differences along the F1 and F2 axes are calculated. RESULT: The results show a reduction of the vowel space in the unstressed condition for both groups, while vowel duration was found to be significantly longer in this condition for the speakers with hearing impairment. In addition, smaller C-to-V carryover co-articulatory effects were found for the speakers with hearing impairment. CONCLUSION: Findings are discussed within the framework of perceptual and production constraints in hearing impairment and with reference to current models of co-articulation.

Aspects of spatio-temporal variability during consonant production by Greek speakers with hearing impairment.

This paper investigates spatio-temporal variability during the production of the lingual consonants /t, k, s, x, n, l, 50% shaded block/ by four Greek speakers with profound hearing impairment and with differences in the intelligibility of their speech. It examines important factors that have been documented to influence intelligibility, i.e. durational variability, articulatory (token-to-token) variability, and coarticulatory patterns. The technique of electropalatography was used to record tongue-palate contact patterns during consonant production in order to examine differences in articulatory variability among speakers and in V-to-C coarticulatory effects. The study reports durational differences in consonant production between speakers with hearing impairment and normal hearing and investigates the relationship between token-to-token variability in tongue-palate contact patterns and duration. The results indicate a negative relationship between duration and variability, i.e. as segmental duration decreases there is an increase in variability in tongue-palate contact patterns. Significant speaker-dependent differences in duration, articulatory variability and coarticulatory patterns are reported and are discussed in relation to differences in intelligibility among the speakers with hearing impairment.

Articulatory variability during consonant production by Greek speakers with hearing impairment: an electropalatographic study.

This study uses the technique of electropalatography to investigate lingual-palatal contact patterns during the production of the consonants /t, k, s, x, n, l, [symbol: see text] by four Greek speakers with profound hearing impairment and with differences in the intelligibility of their speech. The study provides a detailed description of their tongue-palate contact patterns and discusses some of the articulatory parameters that differentiate consonantal articulation between speakers with normal hearing and hearing impairment. Deviant patterns were found for the majority of consonants and involved substitutions, distortions, and epenthesis of segments. The segments that deviated from normal for all speakers were the fricative /s/, the palatal obstruents [c] and [ç], and the tap [symbol: see text]. Significant differences in articulatory variability during consonantal production were also found. The study discusses deviant patterns in consonant production in relation to the differences in intelligibility among the speakers and with reference to data from previous studies.